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The interrelation between the local site conditions and the severity of destruction during earthquakes has increased the necessity for more investigations on soil characterization in recent years. In residential areas, where active seismic methods are problematic for defining soil properties, passive seismic methods have attracted considerable attention due to their cost-effective and non-invasive features. Therefore, we have utilized 35 single-station ambient seismic noise recordings in the seismically vulnerable city of Babol, Iran, to evaluate the site response (including azimuthal variation and resonance frequency), estimate the seismic vulnerability index (K g), and classify the soil based on the Vs 30 of the region. To address the aim, we extract Rayleigh wave ellipticities from ambient seismic noise using their polarization features and employ them to define the azimuthal variations, resonance frequencies, and K g values of the region. In each station, the ellipticity curve is inverted with the support of supplementary geotechnical information to obtain a shear velocity profile. The inversion results have good consistency with borehole and downhole test information. The study identifies a low resonance frequency of 0.9 Hz with a NE directivity for the majority of the city and a Vs 30 range of 180 m/s to 350 m/s. Moreover, the seismic bedrock of Babol City is represented by a 3D Vs model at a depth of 60 m. Our results reveal that the city is vulnerable to seismic hazards due to the thick and low-velocity deposits responsible for high amplification affecting the study region, which combines with a high seismic vulnerability index, particularly in the southern part. This work has applications for future structural design, urban development, and seismic hazard reduction. • The results represent that single-station ambient noise analysis is a cost-effective and reliable method for soil characterization. • Polarization methods are effective in extracting Rayleigh wave ellipticities from ambient noise recordings. • · The city is characterized by a low resonance frequency with an almost NE orientation and seismic bedrock at a depth of 60 m • · According to Iran's No. 2800 seismic code, the region classified as ground type III • · The soil characterization, high amplification and k g value make the region's southern part vulnerable to seismic shaking [ABSTRACT FROM AUTHOR]

As a non-destructive and convenient method, Scholte waves inversion method has been widely used in various engineering applications. However, previous inversion methods treated the seabed sediments as a fully elastic medium, and ignored the porous nature of the sediment. In this paper, a state-of-art inversion model of shear wave velocity, which takes into account the porous property of the seabed, is established based on Bloch's theorems and Biot's theory. Then, the validity of the results is established and the influences of porosity and permeability coefficient of seabed soil are discussed in detail. Finally, an inversion platform using a Python environment is built, and Differential Evolution algorithm and Bayesian approach are employed to obtain the shear velocity profile of the seafloor in the northern North Sea. The calculated results based on the proposed model are highly consistent with the in-situ measurements in the shallow seabed compared to those calculated by the elastic model. This suggests that the influence of porous medium properties on shear wave velocity should be carefully considered for more accurate marine geological surveys. • a novel inversion model of shear wave velocity incorporating the porous properties of seabed sediments is established. • this study quantifies the impacts of porosity and permeability coefficients on the dispersion curves. • the calculated shear wave velocities exhibit a high level of agreement with the in-situ measurements. [ABSTRACT FROM AUTHOR]

Correlations between the liquefaction resistance of sands in spreader dumps of lignite opencast mines on one side and the CPT tip resistance or the shear wave velocity on the other side have been developed based on an extensive experimental study on 10 different sands. The cyclic resistance ratio C R R (N f = 10) for a failure in 10 cycles, defined as the liquefaction resistance herein, was determined from undrained cyclic triaxial tests for all materials. The CPT tip resistance q c was measured in soundings performed in a calibration chamber. The shear wave velocity v S was obtained from measurements in a triaxial cell by means of bender elements. All three quantities C R R (N f = 10) , q c and v S were determined for different relative densities D r . In case of q c and v S also the pressure-dependence was examined in order to derive suitable equations for a pressure-normalization being necessary for the interpretation of field test data, giving values q c 1 and v S 1 for a mean effective stress of p ' = 100 kPa. The procedure for the development of the C R R (N f = 10) - q c 1 and C R R (N f = 10) - v S 1 correlations based on the experimental data is explained. The correlations derived for the various sands in the present study are analyzed with respect to the influence of the grain size distribution curve and compared to respective relationships for natural soils or uncompacted recent artificial fills from the literature. • CPT tip resistance qc of sands from dumps was measured in a calibration chamber • Shear wave velocity vS was measured with bender elements • Liquefaction resistance CRR was obtained from undrained cyclic triaxial tests • CRR-qc correlations for sands from dumps run atter than those from literature • CRR-qc and CRR-vS correlations for dumps depend on grain size distribution curve [ABSTRACT FROM AUTHOR]

The economic losses left by large recent earthquakes are still considerable, and modern society is wanting not only life protection; it is also demanding that buildings can be immediately occupied after a strong earthquake. The performance-based seismic design allows engineers to design structures with a desired seismic performance for a specified level of hazard. This requires a high standard in the different items involved in the seismic design. One of the key factors is associated with the seismic loads, which are strongly dependent on the local ground conditions. Accordingly, an alternative seismic site classification is proposed, which is based on two dynamic parameters of the ground: the equivalent shear wave velocity, V S30-E , that reproduces the dynamic lateral stiffness of the upper 30 m of the ground, and the predominant period of the site, which is proposed to be estimated applying the H/V spectral ratio of ambient vibration measurements. All the details of this site classification are explained in the paper. • V s30 has limitations for capturing the seismic response, it is not associated with the site stiffness. • V S30-E is introduced as a parameter that reproduces the shear stiffness of the upper 30 m of the ground. • The Arias Intensity Spectrum of acceleration records is introduced to evaluate the predominant period of a site. • The H/V spectral ratio of ambient vibrations (HVSR) reproduces de predominant period of a site. • V S30-E and the predominant period (evaluated via HVSR) of a site are proposed for a seismic site classification. [ABSTRACT FROM AUTHOR]

Repeated small shaking events due to earthquakes significantly enhance liquefaction resistance of soils. Analyses of liquefaction case histories show that aged soils in seismically active zones tend to be less vulnerable to liquefaction despite having similar index parameters—such as standard penetration test N-values and shear wave velocities—as young soils. Significant efforts have been devoted to better understand the effects of the cyclic pre-shearing on liquefaction resistance and it was found that this effect depends on the number of cycles and cyclic stress ratio. However, none of these parameters quantify the improvement of liquefaction resistance due to pre-shaking. This study investigates the pre-shearing effects on liquefaction resistance through laboratory tests and centrifuge tests. An attempt was made to explain the effects quantitatively with a single index parameter of the volumetric strain caused by pre-shearing. It was confirmed from triaxial tests that the liquefaction resistance of pre-sheared sand uniquely increased with increasing volumetric strain regardless of the cyclic shear stress ratio and the number of cycles during the pre-shearing. To examine the pre-shaking effects on the liquefaction strength of sand under a level ground condition, centrifuge tests were conducted in this study. Sand models were subjected to small shaking events repeatedly, which were weak enough not to cause liquefaction. It was observed that changes in the index parameters of the models, including soil density (volumetric strain), shear wave velocity, and horizontal earth pressure during the pre-shaking events were very small. At the end of the test, the sand was subjected to a strong shaking event because models that had gone through pre-shaking need larger shaking acceleration to liquefy. Liquefaction resistance was derived from acceleration records with the aid of the cumulative damage theory. The relationship between liquefaction resistance ratio and volumetric strain that occurred in the pre-shaking events coincides with the relationship obtained from the triaxial tests. After the extensive liquefaction event, all index parameters except soil density— K 0 , Vs, liquefaction resistance—tended to return to their original values (before the pre-shaking). • Pre-shaking effects on liquefaction resistance (LR) through triaxial tests and centrifuge tests. • LR of pre-sheared sand uniquely increased with increasing volumetric strain (VS). • LR ratio VS relationship from centrifuge tests agrees well with triaxial results. • This relationship is not changed by the initial fabric of the sand. [ABSTRACT FROM AUTHOR]

This paper presents the results of an experimental research carried out in laboratory aimed at establishing a relationship between cyclic liquefaction resistance (CRR field) and corrected shear wave velocity (V S1) of carbonate sands. Two carbonate skeletal sands, namely Quiou and Dubai, were investigated together with a carbonate non-skeletal sand from Kenya. The programme included also tests on two silica sands prepared and tested in similar conditions for comparison purposes. The research was based on undrained cyclic simple shear tests and bender element tests in triaxial cell performed on reconstituted specimens of sand at different initial density and stress states. The results obtained highlight that data points for carbonate sands are all located to the right of the currently used cyclic liquefaction resistance vs. shear wave velocity curves suggested for silica sands, implying that the latter curves should be considered non-conservative when applied to carbonate crushable sands. An insight into the effect of the initial effective vertical stress on liquefaction susceptibility of carbonate sands was presented and a stress normalization procedure was also proposed. • Higher excess pore pressure ratios and greater fluctuations between loading cycles are observed in carbonate sands. • Carbonate sands exhibit higher or at least comparable liquefaction resistance with respect to silica sands. • Carbonate sands exhibit in general higher shear wave velocities than silica sands when tested at similar initial state conditions. • A procedure based on overburden stress normalized cyclic liquefaction resistance is effectively proposed for carbonate sands. • The existing field-based CRR-Vs curves for silica sands should be considered non-conservative when applied to carbonate sands. [ABSTRACT FROM AUTHOR]

Preshaking by previous seismic activity can significantly affect the liquefaction resistance of saturated sands. Field evidence, cyclic laboratory testing and centrifuge modeling show that: (i) earthquake events that build up excess pore pressures short of liquefaction strengthen the soil; and (ii) liquefying earthquakes may weaken the soil. The paper presents the results of a centrifuge test (Experiment 2), where a 6 m saturated loose silty sand deposit was subjected to 52 successive base shakings. Three types of shakings were used: preshaking Events A, with a shaking duration of 5 cycles, and stronger Events B and C having a duration of 15 cycles, with Events C having the largest input accelerations. A total of 35 Events A, 9 Events B, and 8 Events C were applied at the base of the model in an alternating sequence. All Events C liquefied the deposit, with the Events B inducing liquefaction at the beginning but not at the end of Experiment 2. Events A generally induced excess pore pressures but not liquefaction. In addition to the pore pressures, horizontal accelerations, settlement and densification, and the soil shear wave velocity, V s , were also monitored during the test. The results were compared with those of Experiment 1, reported in a previous publication, where a similar 6 m deposit of the same silty sand was subjected to a different sequence of shakings A and B which did not include any Event C. Conclusions are drawn on the effect of the strong Events C on the deposit's response. Events A, B and C of Experiment 2 are plotted on existing V s –based liquefaction charts. The charts predict well the liquefaction response of the deposit at the beginning of Experiment 2. On the other hand, for shakings near the end of the test, the charts predict liquefaction for the Events B, which by this time have stopped liquefying the deposit due to the previous history of shakings. This result is consistent with the field evidence including the presence of a number of "false positives" in the charts for silty sand sites in the Imperial Valley of California, an area of intense seismic activity. • Earthquake events that build up excess pore pressures short of liquefaction strengthen the soil. • Liquefying earthquakes may weaken the soil. • Vs-based liquefaction triggering charts work well in recent fill but may be conservative for heavily preshaken deposits. [ABSTRACT FROM AUTHOR]

Cement production is an energetically demanding process and one of the most important sources of CO 2 emission in the world. Consequently, the use of more environmentally friendly supplementary materials which can replace at least a part of cement can be efficacious. In the present study, a laboratory investigation on loose sandy soils (D r ≈ 30%) grouted with cementitious materials (cement and natural zeolite) was conducted to investigate the effects of cementation on the shear wave velocity (V s) of grouted sand specimens. The results showed that in all the sand grain sizes and water to cementitious materials ratio (W/CM), the V s of grouted samples increased with an increase in zeolite content up to 30% (Z opt); however, beyond the Z opt , any increase in the zeolite content reduced the V s. In all W/CM and Z percentage, the V s in grouted specimens decreased with increase in the average sand grain size (D 50). The V s increased following the attainment of equilibrium by CaO with SiO 2 and Al 2 O 3 in the grouted sand specimens. • The V s of grouted sands increased with an increase in zeolite content up to 30% (Z opt). • Beyond the Z opt , any increase in the zeolite content reduced the V s. • The V s in grouted specimens decreased with increase in the average sand grain size (D 50). • The V s increased following the attainment of equilibrium by CaO with SiO 2 and Al 2 O 3. [ABSTRACT FROM AUTHOR]

The sand-sawdust mixture has been frequently used in the shaking table test because it is easy to adjust the shear wave velocity of model soil by changing the sawdust content. In this paper, the dynamic properties and the seismic responses of the free field in sand-sawdust mixture as well as the boundary effects of the laminar shear model box were investigated using a series of shaking table tests. The influences of different constitutive models on to the seismic response analysis of the model soil were studied by comparing the numerical results with the experimental results. The comparison shows that the boundary effect mainly influences the model soil within 0.75 times of the soil depth from the box boundary and the impact decreases with the increasing of soil depth. The natural frequency and acceleration amplification factor of the field decrease with the increasing amplitude of the ground motion. The comparison of the seismic response results for different constitutive models of the Hardin-Drnevich, Ramberg-Osgood, and Davidenkov models using the one-dimensional equivalent linearization method indicated that the combination of Davidenkov and Hardin-Drnevich model could improve the accuracy of seismic response for sand-sawdust mixed soil. • Shaking table tests were conducted on the free field in sand-sawdust mixed soil. • The model site has significant amplification effect and filtering effect. • The seismic response and dynamic characteristics of the model field were studied. • The boundary effect on the sand-sawdust mixed soil decreased with increasing depth. • Equivalent linearized constitutive models for sand-sawdust mixed soil were studied. [ABSTRACT FROM AUTHOR]

In-situ shear-strain profile can be used to evaluate soil dynamic behavior with depth, but also safety of buried lifeline and structures due to seismic wave propagation in soil during an earthquake. Using 199 sets of ground-motion data recorded by six geotechnical arrays with 3–7 sensors in 43 earthquakes, the seismic interferometry by deconvolution method is employed to extract shear-wave velocity profile (V s , sw) of seismic wave in each array; ratio of peak particle velocity (PPV) and V s , sw between two successive sensors, PPV/ V s , sw , is computed in each array and assumed to be proxy of the in-situ shear strain. The characteristics of in-situ shear strain profiles in the arrays are studied under seismic loadings in various earthquakes. The relationships of evaluating both the in-situ shear strain profile and the largest in-situ shear strains of the upper soil near the surface are derived from the regression analysis for D and E class sites, respectively. Based on the linear and volumetric threshold shear strains and PGAs and PGVs, the variations of soil behaviors (i.e., linear elastic, nonlinear and plastic behaviors) with the increase of the shear strain or PGA or PGV are studied in the shear strain profiles. The results are as follows. (1) With the increase of PGA and/or PGV in various earthquakes, the in-situ shear strain profiles move towards the larger shear strains and the soil behavior will change to a higher stage or a higher level in the same stage. (2) In the shear strain profile, with the increase of depth, the in-situ shear strains decrease gradually and the soil behavior will change to a lower stage or a lower level in the same stage. (3) Among the shear strain profiles, upper soil has the largest shear strain (γ max) and the shallower the soil depth, the larger the shear strain. The relationships between the γ max and PGV and between the γ max and PGA and PGV combination can be used to evaluate the dynamic behavior of upper soil with less than 30 m at a strong motion array or station for D and E class sites. (4) The in-situ shear strains are highly correlated with the PPV and average shear wave velocity measured by the drilling-hole methods (V s, dh) combination and with the PPV and V s, dh and center depth between two successive sensors (H cd) combination, and increase with the increase of the PPV and decrease with the increase of the V s, dh and/or H cd , respectively. The relationships are recommended to evaluate the in-situ shear strain profile with very high accuracy in the geotechnical array with more than two sensors for D and E class sites. • The characteristics of in-situ shear strain profiles in the geotechnical arrays are studied under various seismic loadings. • Relationships of evaluating the in-situ shear strain profile with very high accuracy are derived for D and E class sites. • The variations of soil behaviors with the increase of shear strain or PGA or PGV are studied in the shear strain profiles. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D), nonlinear total stress finite-element analyses were performed to investigate the seismic deformation patterns for soil slopes. The numerical parametric analyses consisted of 16 models with soil stiffness and strength parameters selected to isolate the impact of yield acceleration, depth of the sliding mass, natural period of the slope, and the slope angle on the deformation patterns. The results indicate that deeper sliding masses experience notable strain localization at the sliding mass depth, while shallow sliding masses experience more distributed straining throughout the entire soil mass. These factors result in larger displacements for the deep sliding masses relative to shallow sliding masses at small k y , whereas shallow sliding masses experience larger movements at large k y. The numerical simulations also show that an increase in shear wave velocity or decrease in slope height result in smaller displacements, although the effect of shear wave velocity is more significant. Importantly, the slope angle notably affects the resulting displacements and when k y is the same. A steeper slope increases displacements for deep sliding masses but reduces the movements for shallow sliding masses. The deformation patterns in the finite element simulations are inconsistent with the sliding block assumptions commonly employed in seismic slope stability analysis and point to the need to develop empirical slope displacement models from finite element simulations. However, this study shows that to capture fully the factors that affect seismic slope displacement the numerical models analyzed must consider a comprehensive set of slope models that vary the depth of the sliding mass, the shear wave velocity, the slope height, and the slope angle in addition to the yield acceleration. • Deeper sliding masses experience notable strain localization at the sliding mass depth, while shallow sliding masses experience more distributed straining throughout the entire soil mass. • Larger displacements for the deep sliding masses relative to shallow sliding masses at small k y are observed, whereas shallow sliding masses experience larger movements at large k y. • An increase in shear wave velocity or a decrease in slope height results in smaller displacements, although the effect of shear wave velocity is more significant. • The slope angle notably affects the resulting displacements and when k y is the same. • A steeper slope increases displacements for deep sliding masses but reduces the movements for shallow sliding masses. [ABSTRACT FROM AUTHOR]

A new approach is presented to develop site signature consistent deep shear wave velocity profiles (V S profile) for the Mississippi embayment using generalized power-law functions. The approach utilizes 24 deep shear wave velocity profiles measured across the embayment to develop power-law shear wave velocity functions for the geologic units observed in the embayment. The velocity functions along with the layer interface boundaries are utilized to generate an initial V S profile, whose Vs is then adjusted to be consistent with the fundamental site frequency (i.e., the site signature). Using the developed approach, model V S profiles at 24 sites throughout the embayment are generated and compared to the corresponding measured Vs profiles. All modeled V S profiles matched the site fundamental frequency within one standard deviation. Percent differences calculated between the modeled V S profiles and measured V S profiles demonstrated good agreement with less than a 10% difference at most depth ranges. However, differences of up to 30% are observed for near surface layers. The V Savg of the modeled and measured V S profiles have a strong association with a Pearson correlation coefficient of 0.95, while the V S30 of the modeled and measured Vs profiles have a Pearson coefficient of 0.49, indicating a weaker association. As an independent verification, model V S profiles are generated at 11 independent sites and compared with the measured V S profiles at these sites. Percent differences calculated between the modeled and measured V S profiles at the independent sites are below 15% at most depth ranges, with a Pearson correlation coefficient calculated for V S150 of 0.75, indicating a strong association. With reasonable layer interface models, this new approach can be used to develop an updated 3D shear wave velocity model for the Mississippi embayment. • Approach to develop site signature consistent pseudo V S profiles in the Misssissippi embayment. • Velocity functions for geologic units found in the Mississippi embayment. • Layering ratio method for discretization of velocity functions. • Theoretical shear wave transfer function and threoretical Rayleigh ellipticity peaks to adjust modeled pseudo V S profiles. • Comparison of modeled and measured V S profiles at sites across the Mississippi embayment. [ABSTRACT FROM AUTHOR]

When large reservoirs are impounded, the reactivation of ancient landslides significantly contributes to erosion. In this study, we investigated the site response of ancient landslides during the initial impoundment of the Baihetan Reservoir. Ambient noise recordings collected at various reservoir water levels were analysed using the microtremor horizontal-to-vertical spectral ratio technique and single-station RayDec method. Our results indicate that, with an increase in the early reservoir water level, the resonance frequencies and spectral ratio amplitude of landslides changed. However, the direction of site resonance did not change. Furthermore, to explain the site response changes, we simulated the pore water pressure and stability of the S2# landslide using Geo-Studio software. We observed that the subsurface shear wave velocity of the slope decreased with an increase in reservoir water. Our study provides a new method for analysing the site response of ancient landslides and a new perspective for studying landslide stability in reservoir areas. • Site response of ancient landslides with reservoir water level rise were discussed. • Subsurface Vs of ancient landslides varies with the rise of reservoir water level. • The relationship between site response and slope stability was explained. [ABSTRACT FROM AUTHOR]

The small strain shear modulus, G max , is an important parameter for characterizing the seismic response of deposits to dynamic loading. The parameter is related to shear wave velocity (G max =ρV s 2 ) only via the soil density. Existing V s correlations established in the laboratory were compiled in this paper and grouped into different general forms. Laboratory V s measurements using the piezoelectric ring-actuator technique, P-RAT, incorporated in conventional oedometer cells, were performed for six Eastern Canadian clay deposits. Specific correlations were established between normalized shear wave velocities, V s1 , with the overconsolidation (OCR) and void ratios (e). The paper examines the applicability of existing correlations by comparing V s1 values obtained from P-RAT correlations to those predicted by published laboratory correlations. While several correlations can be used to predict V s for Eastern Canadian clay, the applicability of other correlations has however been questioned. The analysis reveals the importance of considering the effect of the percentage of fine particles (<2 μm). This effect changes the void ratio variation range, which in turn has a significant impact on V s values. Furthermore, two general correlations are suggested based on P-RAT results and considering the clay content of analyzed sites. These general correlations can be readily used to estimate V s1 values for low and high plasticity clays. [ABSTRACT FROM AUTHOR]

This study developed an evolutionary algorithm, called the telescopic evolutionary algorithm (TEA), for the inversion of the spectral ratio of the horizontal to vertical components of strong motions (eHVSR), based on the diffuse-field concept. We verified the TEA using synthetic eHVSR curves from the literature and examined its convergence stability with respect to the independent variables of the algorithm. Furthermore, we present the application of TEA in the inversion of eHVSR curves for the shear wave velocity of the subsurface structure down to the seismic bedrock at seven stations of the K-NET/KiK-net strong-motion networks in Japan. The corresponding geological maps of the regions from the Geological Survey of Japan as well as the site condition database of K-NET/KiK-net and the Japan Seismic Hazard Information Station (J-SHIS) were processed. Subsequently, the TEA retrieved the Vs profiles of the subsurface structures at these stations to highlight the performance of TEA in various geological settings. Finally, important site proxies were calculated from the retrieved subsurface structures. • A new evolutionary algorithm is applied for velocity inversion based on the diffuse-field concept. • The method uses the horizontal to vertical spectral ratio of the strong ground motions (eHVSR). • Geological maps and borehole logs are processed to assure the most consistency. • The method is verified by synthetic and observed eHVSRs. • The method is verified at various geological settings and complex 2D configuration. [ABSTRACT FROM AUTHOR]

We evaluate seismic fragilities for cantilever retaining walls with three slope angles of backfill (i.e., 0, 10°, and 20°), subjected to the ground motions computed for four site classes (S2, S3, S4, and S5). We collect measured shear wave velocity profiles and select representative profiles. Using one-dimensional site response analyses, surface ground motions are computed corresponding to various site conditions. Numerical models are developed for a cantilever retaining wall with a height of 4 m using the FLAC2D software, and are verified by a comparison with an analytical solution. We analyze the correlations between the seismic behavior of the retaining wall and various ground motion parameters. A probabilistic seismic demand model is introduced to calculate the probabilities of exceeding three limit states of retaining walls, based on the relative wall displacements and settlements of the backfills. We propose a suite of seismic fragility curves which are functions of either the peak ground acceleration (PGA) or cumulative absolute velocity (CAV). In addition, we propose a suite of seismic fragility surfaces using dual ground motion parameters (PGA and CAV). The results highlight that the backfill slope angle and ground motion characteristics have a primary influence on the probabilities. When the backfill slope angle increases from 0 to 20°, the probabilities of exceeding the three limit states increase by up to approximately 1.7, 4.0, and 8.5 times, respectively. Additionally, the probabilities for S3 ground motions with a PGA of 0.4 g are higher than those for S2 motions with the same PGA by up to approximately 5, 16, and 36 times, respectively. • Seismic fragility of a retaining wall with backfill slope angles is assessed. • Effects of ground motion characteristics in South Korea are discussed. • The cumulative absolute velocity greatly influences behaviors of a retaining wall. • A total of 24 sets of fragility curves and surfaces are developed. [ABSTRACT FROM AUTHOR]

The instability of coarse oil sands tailings (CST) is investigated in this study by conducting a series of monotonic direct simple shear tests. Laboratory specimens were prepared using moist-tamping, dry deposition, and slurry deposition techniques to investigate the effect of sample reconstitution method and tailings fabric on CST's instability behaviour. CST specimens were then subjected to constant volume (CV), and constant vertical stress (drained) shearing at three different consolidated relative densities corresponding to loose, medium-dense, and dense conditions. The effects of consolidation vertical stress and void ratio on the instability and post-liquefaction strength of the CST specimens were examined. Shear wave velocity (V S) of the specimens were also measured using a pair of bender elements attached to the top and bottom caps of the simple shearing apparatus. The V S measurements were subsequently used to establish practical relationships with undrained strength ratios and yield friction angle of CST. • The shearing behavior of Oil sand tailings is examined within the critical state framework. • Triggering and post liquefaction strength of Oil sand tailings are being examined. • Effect of fabric on the undrained shearing behaviour of Oil sand tailing is studied. • Non-linear relationships are proposed between undrained shear strength with void ratio and state parameter. • Empirical relationships are also proposed between undrained shear strength with shear wave velocity. [ABSTRACT FROM AUTHOR]

This paper presents the numerical code VibPile for simulation of the nonlinear dynamic response of large monopiles under harmonic loading and installation by vibration or impact driving. VibPile is based on a nonlinear FE model of the pile-soil interaction along the shaft and the tip by elasto-plastic springs representing the near field and elasto-dynamic elements (spring and dashpot) for the far field. While for the shaft friction and tip resistance the classical engineering solutions, such as those by standards or guidelines (e.g. API) and literature, are used in the numerical simulations, new computational models are developed for the dynamic response of the soil inside the pile and the far-field elasto-dynamic springs. What primarily differentiates the present model from the existing ones is the treatment of the soil inside the monopile together with the stiffness at the pile tip. Most existing models are based on the solutions for piles with solid sections or pipe piles in which the soil inside the pile follows the pile vibrations like a solid section. For large diameter monopiles commonly used for offshore wind turbines, both the soil response inside the pile and the stiffness of the pile tip are different. The developed model is verified against the vibro-pile test data collected at Altenwalde, Germany. The results include axial pile strains, accelerations, and shear stresses along the pile shaft and at the pile tip. Both the strains and accelerations as well as the rate of pile driving measured at Altenwalde are reproduced by VibPile with reasonable accuracy. Sensitivity analyses are presented to highlight the effects of the shear wave velocity and shear strength at the pile-soil interface on the pile driving rate. Moreover, the effect of the natural period of the inner soil on the pile driving is investigated. • New simulation model for vibro-piling. • New analytical solutions for dynamic stiffness of hollow, large diameter monopiles for small and high frequencies. • Verification of developed model against detailed large-scale pile-driving tests. • Highlighting importance of soil parameters on vibro-piling simulations. [ABSTRACT FROM AUTHOR]

Seismic site characteristics, specifically depth to stiff glaciated Pleistocene sediments (z gl) and shear wave velocity (Vs) profiles, of the Fraser River Delta (FRD), located in southern Metropolitan (Metro) Vancouver, British Columbia, Canada are determined using the most comprehensive geodatabase to date. The relationships between z gl and theoretical fundamental frequency determined from known thickness of post-glacial sediments and experimental peak frequency from microtremor horizontal-to-vertical ratios (f 1,HVSR) are investigated. A z gl predictive model based on f 1,HVSR is developed for shallow FRD sites (z gl ≤ 56 m) and is compared to existing microtremor horizontal-to-vertical spectral ratio (MHVSR) peak frequency-sediment thickness models developed in other regions in the world. At 16 FRD sites, a combination of active- and passive-source surface wave array methods are performed to obtain the fundamental-mode Rayleigh wave dispersion curve which is jointly inverted with the MHVSR fundamental peak frequency (f 0,HVSR) using three parametrization models with varied layering. The jointly inverted Vs profiles with their uncertainties are presented for the 16 sites and compared with existing proximal Vs profiles measured by other in situ Vs profiling methods. The comparison shows a notable match (9.1% depth-averaged absolute relative difference) to a significant depth of 220 m from the two datasets. In addition, 8 of the developed Vs profiles are co-located with strong-motion accelerograph stations, which allows for correlation between recorded earthquake ground motions and seismic site parameters. The proposed predictive z gl model and validation of evolving non-invasive in situ Vs profiling methods are important for 1D and 2D seismic site effects quantification and mapping in the FRD. • Vs profiles in the Fraser River Delta are established employing non-invasive surface wave methods. • A predictive model to estimate the thickness of post-glacial sediments based on f 1,HVSR is developed. • 16 Vs profiles are obtained from joint inversion of the fundamental-mode Rayleigh wave dispersion curve with MHVSR f 0,HVSR. • The inverted Vs profile matched nearby existing invasive Vs profiles up to 220 m depth. [ABSTRACT FROM AUTHOR]

A statistical analysis has been performed aiming at determining to what extent a qualitative engineering-geological characterization of subsoil may provide constraints to the shear wave velocity (Vs) profile. For this purpose, a large database of experimental values provided by seismic microzonation studies carried out in the last 10 years in Italy has been considered. This analysis suggests that statistical constraints can be provided to Vs values as a function of depth by considering main lithological characteristics of cover terrains and geological bedrock. The effectiveness and unbiasedness of resulting relationships are tested against some experimental situations. This information can be used to feed stochastic numerical simulations aiming at preliminary assessment of probability distribution of the expected seismic response in wide areas where an experimental geophysical/geotechnical characterization of the local subsoil is scarce or unavailable. • Statistical analysis of Vs values as a function of the lithological units and depth. • In cover terrains the distribution of Vs values is a function of soil particle size. • In geological bedrock the Vs values depend on weathering and fracturing of rocks. • Our model constrains the Vs profile by knowing the engineering geological units. • The results are useful to a preliminary estimation of seismic amplification effects. [ABSTRACT FROM AUTHOR]

Liquefaction behavior is investigated in four centrifuge modeling tests performed on loose mine waste rock composed of different ratios of gravel, sand, and fines. These specimens have similar shear wave velocity of about 117–128 m/s. Each centrifuge model was subjected to a 0.27-g sinusoidal base shaking amplitude. It was found that soil liquefaction was observed for all models with the exception of a model with a mixture of 70/30% gravel/sand. Dilative behavior was observed from the acceleration time histories for all models and was dependent on the excess pore pressure development and effective stress. Pore pressure dissipation during shaking was found in the models without fines. Degradation and distortion of shear stress-strain loops were also observed. Larger settlement and volumetric strain were observed after the tests for the models with fines. Based on the results from this study, an increase in sand and fines content causes an increase in liquefaction potential of mine waste rock. • Shear wave velocity of loose waste rocks with 40–70% gravel content is 117–128 m/s. • Under the 0.27-g shaking, liquefaction was found in loose waste rocks up to 7.6 m. • Liquefaction potential increases as sand and fine content increase. • Dilative behaviors are observed when experiencing high pore pressure. • Deformation due to shaking and consolidation are influenced by fine content. [ABSTRACT FROM AUTHOR]

Evaluating the liquefaction potential of gravelly soils using in-situ testing remains a challenge in geotechnical engineering practice. The Chinese Dynamic Cone Penetration (DPT) test provides an alternative for in-situ testing in gravelly soils to Becker Penetration Test (BPT) and the Standard Penetration test (SPT). The Chinese DPT was recently correlated with liquefaction resistance based on field performance data from the M w 7.9 Wenchuan earthquake. In this study, liquefaction resistance was evaluated using the DPT and shear wave velocity measurements at eight sites in Seward and Old Valdez, Alaska, where gravel liquefaction took place and two sites in Valdez, where no liquefaction occurred in the 1964 Alaska earthquake. The DPT-based liquefaction triggering curve predicted liquefaction potential at all test sites with moderate accuracy. N′ 120 blow counts from SPT hammers were generally consistent with those from the DPT hammer after energy correction. Back-calculated energy correction factors were typically within 10% of the theoretical energy correction factor. These results suggest that the DPT can provide liquefaction hazard evaluations accurately and economically for many gravelly soils. Liquefaction evaluations using currently available V s -based triggering curves developed for sands often indicated no liquefaction at sites where liquefaction occurred at the Alaska sites. In contrast, a V s -based triggering curve developed from a data set of gravelly soil sites correctly predicted liquefaction at all sites. • Existing DPT triggering curves correctly evaluate the liquefaction potential of Old Valdez and Seward but not for New Valdez. • Existing sand-based V s triggering curves do not properly evaluate the liquefaction potential for any sites in Alaska. • Gravel-based V s triggering curves perform relatively well in liquefaction evaluation of all the sites. • Reasonable agreement is found between the heavy and light hammer blow counts after linear hammer energy correction. [ABSTRACT FROM AUTHOR]

The effect of strain history on monotonic and cyclic response of intact and reconstituted, low and high plasticity silt deposits have been investigated through a series of constant-volume, staged, stress- and strain-controlled cyclic direct simple shear tests. In many cases the specimens subjected to stress-controlled loading exhibited a progressive increase in cyclic resistance due to beneficial effects of increased density following post-cyclic reconsolidation, apparent pseudo-overconsolidation and presumably increased lateral stresses. Such effects outweighed the detrimental effects of fabric destructing as a result of the prior strain history. However, some specimens exhibited an inconsistent evolution of cyclic resistance when assessed using different shear strain cyclic failure criteria. Symmetric accumulation of shear strains in earlier shearing stages did not consistently result in an increasing trend in the post-cyclic resistance; additionally, increases or decreases in cyclic resistance can occur in subsequent shearing stages depending on the amplitude of the maximum shear strain. Staged, strain-controlled tests were used to investigate the cyclic soil response to small and large shear strains, the latter of which caused a reduction in the cyclic resistance of overconsolidated (OC) silt specimens in the following loading event, confirmed using shear wave velocity, V s , measurements which indicated substantial fabric disturbance following the large strain event. In contrast, normally-consolidated (NC) and OC specimens subjected to multiple stages of small cyclic shear strain exhibited progressive increases in V s , the magnitude of which varied with stress history. The increase in cyclic resistance in the NC specimens was related to increased pseudo-overconsolidation following reconsolidation. The monotonic undrained shear strength of all silt specimens subjected to staged cyclic loading increased following post-cyclic reconsolidation; the increase in strength and changes in volumetric tendencies are governed by the magnitude of post-cyclic reconsolidation and changes in soil fabric inferred from V s , respectively. [ABSTRACT FROM AUTHOR]

Local geology in the Mississippi embayment is a significant source of site effects due to the deep unconsolidated sediments and basin effects near the edge of the embayment. Proper characterization of the velocity structure of the embayment is crucial for site response and seismic hazard studies. In this paper, deep dynamic site characterization was conducted in the Mississippi embayment to develop shear wave velocity profiles down to bedrock at 24 sites using active and passive source surface wave methods. Study sites cover parts of Arkansas, Missouri, Kentucky, and Tennessee, with bedrock depths ranging from 250 to 1115 m. Multimodal joint inversion of surface wave data, which included both Rayleigh and Love wave dispersion and site fundamental frequency was utilized to develop the shear wave velocity profiles (V S profiles). The developed V S profiles provided reasonable site characterization solution and captured the site signature from experimental dispersion data and fundamental frequency. Average shear wave velocity down to bedrock ranges from 462 to 686 m/s and is proportionally related with the site period and depth to bedrock of the site. Average shear wave velocities estimated by previous studies using the resonance period-sediment thickness relationship tend to systematically overestimate the average shear wave velocity in the embayment by 25–40%. Formation velocities calculated for the commonly found geologic units in the embayment, Quaternary, Upper Tertiary, Memphis sand, Paleocene, Cretaceous, and Paleozoic bedrock are approximately 214, 418, 607, 665, 967, and 2211 m/s, respectively. Comparison of the developed V S profiles demonstrated better agreement with related V S profiles generated from direct measurements, but differences up to 30% are observed with the current velocity models of the Embayment. • Deep site characterization in the Mississippi Embayment • Active and passive source surface wave method • Multimodal joint inversion of surface wave data • Geologic formation shear wave velocities for the Mississippi Embayment • Comparisons of deep Vs profiles with exist Vs models in the Mississippi Embayment [ABSTRACT FROM AUTHOR]

We investigate the possibility of obtaining time-weighted average shear wave velocity profiles through a wavelength-depth transformation of experimental dispersion curves from surface wave tests, without a formal solution of the inverse problem. We evaluate this approach on a wide flat-file database (Polito Surface Wave Database, PSWD) of experimental dispersion curves and related shear wave velocity profiles, both from dispersion curve inversion and invasive tests. The results show that the proposed wavelength-depth transformation can be valuable for seismic site evaluations offering an estimation of time-weighted average shear wave velocity profiles very similar to a state-of-the-art inversion of the experimental dispersion curves and with similar uncertainty with respect to invasive tests. This transformation has the advantage of avoiding time-consuming inversion processes, with related uncertainty sources, and any assumption on layer parameterization and a-priori information. Moreover, in conjunction with an experimental evaluation of the fundamental frequency of the site, from independent surveys, the wavelength-depth transformation can be used to get a direct and fast estimate of the position of the engineering bedrock. • Time-weighted average shear wave velocity profiles from surface wave tests through a wavelength-depth transformation. • comparable accuracy than standard surface wave methods and similar uncertainties with respect to invasive tests is obtained. • Advantages in ease of use of the proposed transformation and related assumptions are highlighted. [ABSTRACT FROM AUTHOR]

Accounting for uncertainty in shear wave velocity (Vs) profiles has been recognized to be critical to seismic ground response analysis (GRA) and probabilistic seismic hazard analysis (PSHA). Vs randomization models are among the most widely used approaches to account for this uncertainty, often referred to as aleatory variability within the context of PSHA. Researchers have investigated alternate ways of more realistically accounting for Vs uncertainty, such as randomizing the cumulative shear wave travel time (tts) instead of Vs directly. While some preliminary assessments suggest that tts randomization allows for better management of Vs uncertainty, more validations are needed to guide its use in practice. This study aims to fill a knowledge gap by performing a thorough review of the tts randomization framework and suggesting changes that will lead to improved implementation. Specifically, through the use of real experimental data and Monte Carlo simulations, we identify several issues which, if left unimproved, could lead to bias and unrealistic results. These issues particularly pertain to: (1) methods used for bounding simulated layers, (2) approaches for merging column and bedrock models, and (3) appropriate values of the lognormal standard deviation on tts (σ lntts) and inter-layer correlation (ρ) for randomizing tts. For each issue, we devise recommendations and demonstrate that they provide a clear improvement on the current tts randomization framework. The revised steps put forward in this article do not require any additional model parameters, but rather, simply improve upon the existing methodology. The findings of this study enhance our understanding of the tts randomization framework, and the recommendations we provide will enable researchers and engineers to adopt it more robustly and confidently in engineering practice. ● A procedure for incorporating Vs uncertainty in seismic ground response is revisited and improved ● The procedure is based on randomizing the cumulative shear wave travel time (tts), rather than absolute Vs ● Real experimental data and Monte Carlo simulations are used to identify several issues with the current procedure which, if left unimproved, could lead to bias and unrealistic results ● For each issue, we devise recommendations and demonstrate that they provide a clear improvement on the current tts randomization framework ● The recommendations we provide will enable researchers and engineers to adopt tts randomization more robustly and confidently in engineering practice [ABSTRACT FROM AUTHOR]

Construction of vertical spectra (V) for scenario- and intensity-based seismic performance assessment is proposed based on scaling of the associated horizontal spectral ordinates (H) through respective V/H spectral ratios. Geometric mean of the spectra along and normal to the principal plane components is considered as the intensity measure of the horizontal component. V/H spectral shape is constructed using a large database (PEER-NGA-WEST2) of strong motion records contingent on the magnitude of the event, epicentral distance and average shear wave velocity. The procedure is based on the ratio of median vertical-to median horizontal-spectral ordinates which are shown to be well representative of the median of V/H spectral ratio. The construction is based on median response of the scenario and also applies to the design level (of a particular facility located in a specific site, which is also governed by a scenario) under certain assumptions and involves two steps: construction of normalized V/H spectra with unity at zero period scaled by the ratio of median vertical-to median horizontal- PGA (beta). The normalized V/H spectrum is shown to be characterized by three control points. An empirical estimate is proposed for beta as a function of epicentral distance. Normalized V/H spectra are further idealized for use with the intensity-based assessment per seismic codes. Vertical spectra using the proposed framework are compared with the various recommendations reported in the prior art including seismic codes and recorded events. PESMOS and COSMOS databases of strong motion events recorded in the Indian subcontinent are also used during the assessment. • Vertical spectra for scenario- and intensity- based assessment is proposed. • Recommendation for V/H spectral shape. • Prediction for ratio of vertical-to horizontal peak ground acceleration. • Comparison with GMPM of V/H. • Assessment against recorded ground motion. [ABSTRACT FROM AUTHOR]

The correlation of shear wave velocity (V s) with piezocone penetration test (CPTu) parameters is investigated in post-glacial sediments along the St. Lawrence and Saguenay rivers, Southern Quebec, Canada. The compiled database includes 991 CPTu- V s measurements at 40 sites. The objectives are to examine the applicability of existing CPTu- V s correlations, identify the main CPTu parameters and develop specific CPTu- V s correlations that account for the effects of soil type (sandy or clayey) and geological setting (Champlain or Laflamme sea sediments). Results reveal that the application of existing correlations is biased in varying degrees, denoting a need for site-specific correlations for the study area. Multivariate regression analyses confirm the importance of cone tip resistance and depth as V s predictors assisted by normalised pore pressure and soil behaviour type index. Consideration of soil type and geological setting helps reduce uncertainties in CPTu- Vs correlations for fine-grained soils. • Seismic piezocone data for coarse-to fine-grained soils are analysed. • Existing piezocone penetration (CPTu) vs shear wave velocity (V s) correlations are evaluated. • The V s prediction ability of different CPTu parameters is analysed. • Representative correlations considering CPTu-based indexes are proposed. • The effect of the geological setting on CPTu- V s correlation is examined. [ABSTRACT FROM AUTHOR]

In this study, correlations between the shear wave velocity of granular materials and various descriptors of grain morphology are investigated. Based on a comprehensive study of the literature different shape descriptors used in previous studies are summarized. The suitability of the various grain shape descriptors to describe the shear wave velocities of three materials with significantly different grain shape, crushed glass, natural sand and glass beads, is analyzed. The shear wave velocities are obtained from a series of torsional resonant column tests under different confining pressures. Recommendations regarding the suitability of certain morphological parameters are given. Lastly, a novel graphical presentation by means of the grain shape distribution curve is proposed, which eases the comparison of various granular materials and provides an information about the range of a certain grain shape descriptor which can be quantified by a shape uniformity coefficient. Correlations of this coefficient with the shear wave velocity data are also explored and found to yield comparable trends like the mean grain shape which has been employed in past studies. • Correlations between the shear wave velocity of granular soils and various grain morphology descriptors are investigated. • The shear wave velocities are obtained from torsional resonant column tests under different confining pressures. • Recommendations on the suitability of certain morphological parameters in capturing the variation of grain shape on the wave velocity are given. • Furthermore, information regarding the grain shape distribution should also be provided for capturing the grain shape holistically. [ABSTRACT FROM AUTHOR]

The use of horizontal to vertical spectral ratios (HVSR) of earthquake ground motions has become a standard technique to characterize sites, especially those lacking subsurface measurements. Several studies have developed relationships between HVSR results and time-averaged shear-wave velocity in the upper 30 m (V S30). Other studies have utilized standard spectral ratios calculated from horizontal ground motion Fourier amplitude spectra to estimate V S30. Anchorage, Alaska (USA), has a network of strong-motion recording stations, many of which have no site-specific subsurface characterization. This study compares measured V S30 and HVSR results from 18 strong-motion stations to four regional models developed by others. A relationship between the 1 Hz band-averaged (0.5–2.5 Hz) spectral amplification results and V S30 is presented. V S30 estimates for the strong-motion stations are made, and a regional model is developed between HVSR and V S30 , both in terms of f peak (the frequency of the peak HVSR amplitude) and A peak (the amplitude of the peak). In addition to the regional model, additional V S30 data from other sites in Anchorage, including 19 downhole V S30 measurements and 22 microtremor V S30 estimates from others, are used with the strong-motion station V S30 estimates to develop a V S30 contour map of Anchorage. The contouring represents the spatial distribution of the site classes of the local building code, which are based on V S30. This map may be incorporated into planning documents for future developments in the city. • This study develops a V S30 map of Anchorage, Alaska utilizing a combination of measured data and data estimated from HVSR and SSR methods. • Several HVSR-derived regional equations for estimating V S30 are provided. • The VS30 map provides engineers and planners a first estimate of site response to use for future development in the city. [ABSTRACT FROM AUTHOR]

A reliable prediction of the excess pore pressure build-up is essential in performing an effective site response analysis. In this study, centrifuge test measurements on mildly sloping ground subjected to ramped sinewaves are utilized to test the performances of three pore pressure models implemented in a one-dimensional (1D) site response analysis program conditioned on accumulated strain, energy, and stress, respectively. Three shear wave velocity (V s) and relative density (D r) profiles are utilized to account for the uncertainties in the soil properties. The pore pressure outputs calculated with the strain-based model is shown to be highly sensitive to V s. Agreeable predictions are obtained near the surface, whereas the pore pressures at depths of 3 and 4 m are underestimated. The energy-based model significantly underestimates the pore pressure for all cases. The stress-based model is revealed to be less sensitive to V s , whereas it is considerably dependent on D r. Exceptional fit is achieved with a cone penetration test based D r profile, whereas pore pressure is overestimated using the empirical liquefaction triggering chart to determine the cyclic strength. Further comparisons of the acceleration time histories illustrate the use of both the strain and energy-based models provide slightly higher and better estimates of the surface ground motion compared with that calculated with the stress-based model. Considering the sensitivity of the outputs, it is recommended to account for the uncertainties of soil properties and also to use both strain and stress-based models in performing 1D effective stress site response analyses. • Three pore pressure model implemented in 1D site response analysis program is tested. • Strain-based model provides reliable estimates near the surface. • Energy-based model produces poor fit with the recordings. • Stress-based model yields best estimate when Dr estimated from CPT is used. • It is recommended to use both strain and stress based models to account for uncertainty. [ABSTRACT FROM AUTHOR]

Multichannel analysis of surface waves (MASW) has played an important role in shear wave velocity survey of subsurface. Modern urban engineering construction needs more and more high-resolution detection of shallow underground objects. However, the traditional MASW method will reduce the detection depth when the receiving array length is reduced to improve lateral resolution. We propose a modified multichannel analysis method of surface waves based on short array stacked correlation gather (SCG-MASW) to solve this problem. The geometry of SCG-MASW is same as MASW, but surface wave dispersion is derived from short array stacked correlation gather instead of shot gather. Both theoretical and experimental data show that the SCG-MASW can improve the lateral resolution by using short receiving array, while not reducing the detection depth. • A modified multichannel analysis method of surface waves is proposed. • The modified method obtained dispersion curve base on short array stacked correlation gather. • This method can improve the horizontal resolution without reducing the detection depth. [ABSTRACT FROM AUTHOR]

The V S 30 of 89 stations in Republic of Korea are predicted using semi-empirical relationship between natural frequency (f p) selected from horizontal-to-vertical spectral ratio (HVSR) and time averaged shear wave velocity down to 30 m depth (V S 30). The installation of seismic stations has been accelerated in Republic of Korea after two damaging earthquakes at 2016–2017, but the majority of stations do not have geophysical investigation yet, and even for a few stations the investigation is prohibited due to deforestation issue and civil complaints. The objective of this study is to predict V S 30 for stations without investigation using f p to V S 30 relationship. The HVSR of 48 stations with measured V S 30 are analyzed to find appropriate f p selection and the best-fitted model. We found that the f p - V S 30 relationship is weak if the peak is not distinct and HVSR amplitude is low, and the model developed for the stable continent region fits the best. • V S 30 of 92 seismic stations located on surface in South Korea are newly estimated. • F p from HVSR is highly correlated to V S 30 if it is defined from a distinct peak with high HVSR amplitude. • F p -V S 30 relationship for Korean stations is similar to the relationship developed for Central and Eastern North America. • The standard deviation of residuals is lower than those by proxy-based methods. [ABSTRACT FROM AUTHOR]

Liquefaction of gravelly soil has been reported for several historical earthquakes. However, the data size remains insufficient for guaranteeing a high-performance prediction model, especially because the data quality used for the model building has not been evaluated in previous studies. In addition, the significant factors used to construct a gravelly soil liquefaction model remain unclear. To overcome these issues, the following key efforts are made in this study: (1) significantly expanded databases are accumulated for filed performance case histories obtained using dynamic penetration and shear wave velocity tests; (2) the data quality is improved by screening, correction, and repair of filed data case histories; (3) a framework is proposed to identify significant factors for gravelly soil liquefaction; and (4) the thresholds for two triggers of gravelly soil liquefaction are updated as H n (the impermeable capping layer) larger than 0 m and D n (the thickness of the unsaturated zone between the groundwater table and the capping layer) less than or equal to 4 m. Data cleaning and identification of significant factors can both improve the predictive performance of a model. • The DPT and Vs databases of the gravelly soil liquefaction are compiled and cleaned. • A four-step approach is proposed to select the significant factors of gravelly soil liquefaction. • The relationship between N 120 and V s is refitted considering the correction of the depth of gravelly soil. • An improved CRR* - V s1 curve that is considerably more accurate than the A&S model is proposed. [ABSTRACT FROM AUTHOR]

The spatial incoherence of ground motion during an earthquake can have a significant effect on the dynamic response of engineering structures such as bridges, dams, nuclear power plants and lifeline facilities. The main objective of this paper is to study the effect of anisotropic heterogeneities in a soil layer overlying homogeneous bedrock on the lagged coherency of surface ground motion. A set of numerical experiments is performed based on 2D spatial variability of shear-wave velocities modeled as a homogeneous stationary random field and discretized by the EOLE method (Expansion Optimal Linear Estimation). Seismic ground motions were simulated using FLAC2D software in the 1–25 Hz band for a plane wave excitation with SV polarization. The soil is characterized by horizontal and vertical autocorrelation distances ranging between 5 and 20 m and 1 and 2 m, respectively, and a coefficient of variation of the shear-wave velocity varying between 5% and 40%. The synthetic seismograms calculated for 9 parameter sets (100 realizations each) clearly show seismic waves scattering and surface waves diffracted locally by the ground heterogeneities, generating large spatial variations in coherence mainly controlled by the coefficient of variation of shear-wave velocity. Consistently with existing models and experimental data, the numerical coherency curves decrease with frequency and receiver distance, however at a rate which is lower than that observed in the experimental data. This difference is probably due to intrinsic attenuation that is not accounted for in the simulations and/or to our 2D simulations that do not reproduce the complete wavefield. The numerical average coherency curves for each parameter set exhibit maxima within narrow frequency bands caused by the vertically trapped body waves and surface wave propagation properties within the average ground model. This interpretation is supported by experimental data recorded in the Koutavos-Argostoli valley (Greece). • The shear-wave velocity coefficient of variation is controlling the coherency of the surface ground motion. • The effect of the horizontal autocorrelation distance is observed for small inter-receivers' distances. • Maximum coherency is observed at the resonant frequencies and the Airy phase. • This interpretation is validated in both numerical and experimental observations. • The atanh transformation is not relevant for coherency standard variation estimation. • Existing coherency models underestimate the coherency of synthetic ground motions. [ABSTRACT FROM AUTHOR]

Non-invasive surface wave methods have become a popular alternative to traditional invasive forms of site-characterization for inferring a site's subsurface shear wave velocity (Vs) structure. The advantage of surface wave methods over traditional forms of site characterization is that measurements made solely at the ground surface can be used routinely and economically to infer the subsurface structure of a site to depths of engineering interest (20–50 m), and much greater depths (>1 km) in some special cases. However, the quantification and propagation of uncertainties from surface wave measurements into the Vs profiles used in subsequent engineering analyses remains challenging. While this has been the focus of much work in recent years, and while considerable progress has been made, no approach for doing so has been widely accepted, leading analysts to either address the propagation of uncertainties in their own specialized manner or, worse, to ignore these uncertainties entirely. In response, this paper presents a new, effective, and verifiable method for developing uncertainty-consistent Vs profiles from inversion of surface wave dispersion data. We begin by examining four approaches presented in the literature for developing suites of Vs profiles meant to account for uncertainty present in the measured dispersion data. These methods are shown to be deficient in three specific ways. First, all approaches are shown to be highly sensitive to their many user-defined inversion input parameters, making it difficult/impossible for them to be performed repeatedly by different analysts. Second, the suites of inverted Vs profiles, when viewed in terms of their implied theoretical dispersion curves, are shown to significantly underestimate the uncertainty present in the experimental dispersion data, though some may appear satisfactory when viewed purely qualitatively. Third, if the uncertainties in the implied theoretical dispersion curves were to be examined quantitatively, which has not been done previously, there is no obvious remedy available for the analyst to resolve any inconsistency between the measured and inverted dispersion uncertainty. Therefore, a new approach is proposed that seeks to remedy these shortcomings. First, beyond appropriate considerations that must be given to all inversions, the new approach is governed by only one user-defined input parameter, to which it is not overly sensitive. Second, the new approach is shown to produce suites of Vs profiles whose theoretical dispersion curves quantitatively reproduce the uncertainties in the experimental dispersion data. Third, the final step of the procedure requires the analyst to compare the measured and inverted dispersion uncertainties quantitatively, and should the analyst find the results of the new approach to be lacking, clear guidance is provided on the additional actions necessary to produce Vs profiles whose theoretical dispersion curves better account for the experimental uncertainty. Using two synthetic tests and a real-world example, the procedure is shown to produce suites of Vs profiles that accurately capture the site's Vs structure, while rigorously propagating the dispersion data's uncertainty through the inversion process. • A procedure is developed to quantify Vs uncertainty from surface wave inversion. • The procedure results in dispersion uncertainty-consistent Vs profiles. • The procedure is new, effective, and verifiable. • The procedure propagates experimental dispersion uncertainties into the inverted Vs profiles. • The procedure is demonstrated using synthetic and real-world examples. [ABSTRACT FROM AUTHOR]

In the present study, the difference between the peak seismic response measures recorded on building basements and those at nearby free-field conditions is studied by means of estimating the high-frequency spectral decay parameter, " κ " (known as "kappa"). Computation of " κ " is performed for selected accelerographic stations belonging to three strong motion networks, namely the Hellenic National Accelerographic Network (HNAN) in Greece, the Center for Engineering Strong Motion Data (CESMD) in California, USA and the Building Research Institute (BRI) in Japan. Parameter " κ " is computer according to Anderson and Hough (1984), while an automated signal energy-based procedure is developed to calculate the S-wave windows of each waveform, accounting for any errors. Site-specific restrictions on the upper frequency limit, f 2 , for the calculation of " κ " at the foundation level are imposed, based on the empirical transfer functions between foundation and free-field motions. Based on the above procedure, non-linear regression analyses are conducted to relate " κ ", as computed for free-field and foundation motions (κ ff , - κ fnd) , to magnitude M w , source-to-site distance R epi and shear wave velocity V S30. Simulation of ground motions though the point-source stochastic method is accomplished, utilizing the regression expression to define " κ " and assess its effectiveness to predict the variation of intensity between free-field and foundation motions as a proxy for assessing soil-structure interaction effects. It is shown that the regression-based expressions, combined with stochastic simulations, consist a promising tool for correcting seismic motions recorded at a building foundation or basement levels and thus, for reliably predicting the corresponding intensity and characteristics of the actual "building-free" ground motions. • Computation of " κ " from free-field and foundation recordings. • Association of " κ " with Soil-Structure interaction effects. • Empirical expressions for " κ " of foundation and free-field motions. • Implementation of empirical expressions and stochastic simulation. • Potential correction of within-building records to be used for GMPE development. [ABSTRACT FROM AUTHOR]

In the program of LEAP-Asia-2019, three dynamic centrifuge model tests on a 5-degree sloping ground composed of saturated Ottawa F-65 sand have been conducted at Zhejiang University to validate the generalized scaling law (GSL) by using the technique of "modeling of models". Firstly, the advantages and possible limitations of the generalized scaling law are revisited. Then a new scaling relation (GSR) treating the stiffness instead of the strain as an independent scaling factor is proposed in the frame of the generalized scaling law, and it further considers the effect of modulus reduction over wide strain range. Shear wave velocities of three models measured by bender elements and non-destructive step wave are analyzed to check the validity of Iai's Type II GSL at small strain range, and the response of acceleration, excess pore water pressure and displacement are analyzed to validate Iai's Type II GSL at large strain range. This study shows that Iai's Type II GSL generally applies well for small strain conditions and even the dynamic response of acceleration and pore pressure, but will introduce considerable errors for dissipation time and permanent displacement under large strain conditions. The proposed GSR exhibits better performance for all model tests from small to large strain levels. • New scaling relation (GSR) is proposed by considering soil nonlinearity based on the generalized scaling law. • Centrifuge model tests of soil liquefaction were used to validate Iai's GSL by "modeling of models". • Iai's Type II GSL applies well for dynamic response under small strain condition (γ ≤ 0.01%). • Iai's Type II and Type III GSL correspond to the proposed GSR at small and large strain levels respectively. [ABSTRACT FROM AUTHOR]

This paper presents the results of an experimental campaign in Macerata (Italy). In the first step, the research addresses the site characterization by presenting the in situ and laboratory examinations results. In a second step, the study focuses on the more in-depth interpretation of the raw signals acquired by the SDMT in the 100 m deep borehole. The cross-correlation between SDMT signals represents the standard method to estimate the velocity of the shear waves. The authors attempted to assess any dependency of the shear wave velocity on the wavenumber by applying a moving bandpass filtering to the signals acquired in the 100 m deep borehole. In seismic engineering practice, the standard mechanical models of soils are representative of non-dispersive media. This assumption originates from the scarcity of experimental investigations on the dispersion laws of soils and the confidence in dispersion's possibly negligible effect. However, a purely non-dispersive medium does not exist, and all media do show some dispersion features: the phase velocity of shear waves may depend on the wavenumber. • Geotechnical characterization of a site in Macerata (Italy). • Estimate of the velocity of propagation of the shear waves using the seismic dilatometer. • Estimate of the dispersion curves of the shear waves. • The dispersion curves tend to infinity as the wavenumber tends to zero and lower to zero as the wavenumber raises. • The standard estimate of the shear waves may lead to a conservative soil classification. [ABSTRACT FROM AUTHOR]

Reduced-scale centrifuge experiments are widely used to simulate complex boundary-value geotechnical problems and to validate numerical or analytical models. The recordings obtained from these experiments can also help researchers back-calculate soil properties, which are subsequently used in model analysis. In this paper, we investigate how the container boundaries and scaling at different levels of centrifugal acceleration can influence the evaluation of soil properties in centrifuge for a sample of medium-dense, dry Ottawa sand. Soil dynamic properties at both small and large-strains are first identified through the theoretical solutions of wave propagation and the nonparametric method using accelerometer recordings at different distances from the container boundaries. Then, coupling effects are evaluated between the flexible-shear-beam container walls and the soil specimen, assuming the system behaves as a composite shear material. Results indicate that both small-strain and strain-compatible shear wave velocities obtained from accelerometer recordings were not highly sensitive to their location with respect to the container boundaries. However, without considering the geometry and shear stiffness of container, the shear wave velocity profile could be underestimated significantly, while the computed damping ratios were less influenced. Although volumetric settlements measured on the soil surface were strongly influenced by boundary effects, the identified threshold strains and the volumetric behavior of sand were consistent under the high-frequency environment of the centrifuge and low-frequency, drained laboratory element tests. • The effect of container boundaries and centrifugal acceleration on the evaluation of soil properties was investigated. • Soil dynamic properties at both small and large-strains were identified from the accelerometer recordings. • The obtained Vs was not highly sensitive to their location with respect to the container boundaries. • The Vs profile could be underestimated significantly due to ignoring the geometry and shear stiffness of container. • The threshold strains and volumetric behavior were consistent under the high-frequency centrifuge and low-frequency element tests. [ABSTRACT FROM AUTHOR]

Ground response analysis is greatly affected by uncertainties inherent in soil parameters. However, accurate reliability analysis of the ground response and determination of the reliability index associated with Peak Ground Acceleration (PGA) at the ground surface considering soil layers cross-correlation is very time-consuming. In this paper, by considering two real sites and using frequency domain analysis, the layered-soil sites are regarded as serial components of a cross-correlation system. Then the corresponding reliability index of each is obtained via proposed methods. System reliability indices of the sites PGAs are finally determined by combining the components based on their corresponding correlation through the Sequential Compounding Method (SCM) as a powerful technique for reducing computational costs. The reliability indices obtained by the proposed methods are then compared with the Monte Carlo Simulation (MCS) and Subset Simulation (SS) methods known as efficient MCS. The results show that, in addition to reducing the computational time, the proposed methods represent high accuracy for calculating the reliability indices of ground surface PGAs of the sites. • System reliability analysis of ground response based on three proposed methods is presented. • Shear wave velocity and unit weight of the soil layers are considered as stochastic parameters. • Real sites PGA reliability indices are determined by FORM- and Hasofer-Lind-PSO-SCM methods. • The results of FORM-SCM and Hasofer-Lind-PSO-SCM methods are compared with the MCS and SS. • The proposed methods calculate reliability indices quickly and considering soil layers cross-correlation. [ABSTRACT FROM AUTHOR]

There is an increasing interest in utilizing surrogate models to perform the global sensitivity analysis (GSA) for the uncertainty quantification since they allow to quantify efficiently the relative importance of each input parameter with relatively small computational costs. This paper aims at investigating the feasibility of applying this method to a stochastic soil-tunnel system in seismic conditions. An advanced technique named sparse polynomial chaos expansions (SPCE) is introduced to build a surrogate model that allows performing a GSA combined with the Sobol' indices. The accuracy and efficiency of the SPCE-GSA method are validated by comparison with the true numerical predictions and Monte Carlo simulations. Parametric sensitivity analyses are performed for a wide range of the soil shear wave velocities, ground motion intensities, probability distribution types, and coefficients of variation, assuming a nonlinear soil behavior. The influences of the sampling size, polynomial degree, and ground motion characteristics on the variability in the sensitivity indices are evaluated. The results show that the soil shear wave velocity and modulus reduction factor are the two variables that significantly affect the seismic deformations of tunnels. • Random soil properties are considered. • Sparse polynomial chaos expansion based global sensitivity analysis (SPCE-GSA) is proposed. • SPCE-GSA method is verified with Monte Carlo simulations. • Soil shear wave velocity is found to have the most influence on tunnel deformations. [ABSTRACT FROM AUTHOR]

Near-surface soil conditions can significantly alter the amplitude and frequency content of incoming ground motions – often with profound consequences for the built environment – and are thus important inputs to any ground-motion prediction. Previous soil-velocity models (SVM) have predicted shear-wave velocity profiles based on the time-averaged shear-wave velocity in the upper 30 m (V S30). This article presents a generic soil-velocity model that accounts both for near-surface conditions (V S30) and deeper geologic structure, as represented to the depth at which the profile reaches a velocity of 1.0 km/s (Z 1.0). To demonstrate the advantages of our new SVM, we apply it to the Cascadia Region of North America, where numerous geologic basins and glaciated landscapes give rise to a wide range of V S30 and Z 1.0 combinations. This soil velocity model yields good estimates of site response across all site conditions, and significantly improves upon a model calibrated using only V S30 data. In conjunction with existing models that describe the deep velocity structure of the region (e.g., (Stephenson et al., 2017) [27]; the proposed model is particularly suited for use in regional-scale predictions of site response, liquefaction, landslides, infrastructure damage, and loss. The proposed methodology is broadly applicable to the development of SVMs elsewhere, and with improved understanding of near-surface and deep velocity structures, can facilitate more accurate ground-motion predictions globally. • Predicts near-surface shear-wave velocity profiles while accounting for deeper structure. • Soil profile predictions are conditioned on V S30 and Z 1.0 • Suited for large-scale/regional site profile and amplification estimates. • Better estimates site response than existing models calibrated to other regions. [ABSTRACT FROM AUTHOR]

An improved correlation between shear-wave velocity V S and cone penetration test (CPT) parameters was derived for the Groningen region, the Netherlands, using a set of 154 pairs of CPTs and seismic CPTs. An analysis of a high-quality subset showed that the subdivision into Holocene versus Pleistocene intervals or into cohesive versus non-cohesive intervals did not significantly improve correlation, nor did filtering out of the transition intervals between clay and sand in the non-cohesive dataset. In addition, using q t or q c resulted in similar regression results. We therefore propose a single new equation and we applied this to all available CPTs in the region. The analysis of the fitting bias showed that there is a trend relative to the measured V S. We therefore recommend performing SCPT measurements when very soft soils (V S < ~100 m/s) are encountered, rather than relying on the empirical correlation based on CPT parameters. The comparison of the V S30 values from CPTs to the model V S30 of Groningen shows that correlation is excellent: 90% of the calculated V S30 values from the CPTs fall within one standard deviation of the V S30 of the corresponding geological zone of the model. Although the resulting CPT- V S correlation is specific for the Groningen region, the approach can be applied to other regions with a paired SCPT-CPT dataset. • High-quality set of 154 co-located CPTs and seismic CPTs is available for Groningen. • Regression on V S = f(q c , f s , effective stress) has been applied to predict V S. • No soil classification is required to convert raw CPT data to V S and V S30. • No significant difference between correlations for Holocene and Pleistocene soils. • Systematic bias results in overprediction of V S in very soft soils. [ABSTRACT FROM AUTHOR]

The current code-conforming seismic lateral load patterns are implicitly derived based on the dynamic solutions of fixed-base elastic structural systems, without considering the effects of hysteretic characteristic and soil-structure-interaction (SSI). Consequently, such lateral force patterns may not be applicable for the seismic design of nonlinear deteriorating structural systems. In this study, the analytical model was constructed using the shear building model. The peak-oriented modified I–K model and sway-rocking (S -R) model were employed to simulate the deteriorating behavior and SSI effects, respectively. A practical optimization design procedure for optimal lateral load pattern was developed based on the uniform damage distribution. The influence of main parameters on the new lateral load pattern was comprehensively investigated, including the parameters of the S -R model and the peak-oriented modified I–K model, ground motion excitations, fundamental period, target ductility, damping ratio and so on. The quantified expression of the new lateral load distribution was proposed as a function of fundamental period, the target ductility, aspect ratio and shear wave velocity. The results show that the structures designed according to the proposed lateral force pattern experienced obviously less damage than the code-conforming pattern. • The optimization procedure of deteriorating SDOF system for uniform damage is developed. • Effects of structural and seismic inputs parameters are comprehensively investigated. • The new lateral load distribution pattern is proposed. [ABSTRACT FROM AUTHOR]