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This paper presents the development of a shear-wave velocity (V S) model of reference site conditions in South Carolina for site response analysis and seismic hazard mapping. Model development involves creating contour maps of two geologic surfaces in the Coastal Plain with high contrasts in V S and combining the results with median V S profiles that extend to hard rock (V S ≥ 3000 m/s). Uncertainties associated with the contour maps of depth are captured in maps of the standard prediction error. Values of time-averaged V S in the top 30 m (V S,30) ranging from 1183 to 1538 m/s and 354 to 385 m/s characterize the reference site conditions in the Blue Ridge and Piedmont regions and the Coastal Plain region, respectively. The model is divided into 14 zones to facilitate site response analysis and to avoid over-smoothing resonances due to the impedance contrasts. This study is part of a larger effort to develop statewide probabilistic seismic hazard maps for the South Carolina Department of Transportation. • A geology-based, shear-wave velocity (V S) model of reference site conditions in South Carolina is developed. • Two depth contour maps are created: 1) Top of the Jurassic and older basement; and 2) Bottom of the Santee Limestone. • V S30 for reference outcrop site conditions are between 354 m/s and 385 m/s in Coastal Plain of South Carolina. • In the South Carolina Blue Ridge and Piedmont, V S30 for reference outcrop site conditions range from 1183 to 1518 m/s. • South Carolina is divided into 14 zones for the purposes of site response analysis. [ABSTRACT FROM AUTHOR]

This paper summarizes results of laboratory investigations performed to quantify the influence of diagenesis (or aging processes) on the peak shear strength and dilatancy of an uncemented Pleistocene age sand sampled near Charleston, South Carolina. Drained triaxial compression tests were performed on high-quality intact specimens retrieved using the in situ freezing and sampling method, and on remolded specimens prepared with matching densities. The stress-strain behavior of intact specimens is accompanied by dilation and a peak shear value, whereas remolded specimens generally contracted throughout shearing. An age-dilatancy term is added to a dilatancy index equation to account for the difference between intact and remolded peak friction angles. The resulting equation suggests that dilatancies due to age and density are suppressed with increasing confining pressure. A profile of peak friction angle with depth is established from the results and compared with estimates from empirical relationships. [ABSTRACT FROM AUTHOR]

A new relationship for estimating the in situ at-rest lateral stress coefficient (K0) in sands consisting predominantly of silica particles is derived in this technical note using the calibration chamber test results reported in the literature. Variables in the relationship, in order of significance, are overconsolidation ratio, dilatometer horizontal stress index, and normalized cone tip resistance. Values of in situ K0 estimated with the new relationship generally compare well with K0 determined from self-boring pressuremeter tests. Estimates of K0 in Pleistocene sands are, on average, about 10% higher than in Holocene sands. [ABSTRACT FROM AUTHOR]

The procedures used to freeze and sample a Pleistocene sand deposit near Charleston, South Carolina to preserve and study the effects of diagenesis are presented in this paper. Based on the results of geotechnical tests and a feasibility ground freezing study, a freezing system with a central freeze pipe was installed to target a column of clean sand 1 m in radius and 2.3 m in length. Liquid nitrogen was continuously supplied to the freeze pipe fabricated to freeze the sand between depths of 1.8 and 3.8 m below the ground surface for 270 h. Frozen sand cores taken from five locations 0.65 to 0.7 m away from the central freeze pipe indicate the ground was frozen between depths of 1.8 and 3.8 m at all but one location. Ground temperature measurements, growth of the frozen zone, and the amount of liquid nitrogen consumed are presented and compared with predicted values. Recorded temperatures indicate that the freezing was influenced by the direction of groundwater flow, the flow rate of liquid nitrogen, and the location of the liquid nitrogen inlet pipe within the central freeze pipe. [ABSTRACT FROM AUTHOR]

Liquefaction triggering of the outcropping 200,000-year-old Ten Mile Hill beds sand facies (Qts) near Charleston, South Carolina is characterized in this paper. The characterization includes evaluating the relative susceptibility to liquefaction of Qts assuming a uniform seismic load and using seismic cone penetration testing at 46 sites, the ratio of measured small-strain shear wave velocity to estimated small-strain shear wave velocity (MEVR), and the liquefaction potential index (LPI). The computed LPI values indicate a slight decrease in the liquefaction susceptibility of Qts moving away (5 to 30 km) from the likely source of the 1886 Charleston earthquake (M w ~ 7). Also characterized is the liquefaction potential of Qts during the Charleston earthquake and a range of other earthquake loadings. The results for the range of other earthquake loadings are summarized in terms of liquefaction probability curves, which provide a method for mapping liquefaction potential in Qts. A back-calculated, lower-bound diagenesis correction factor of 1.11 for areas of Qts where liquefaction surface manifestations were not observed agrees well with the published data. • No consistent trends with distance to fault in the liquefaction susceptibility evaluation of Qts. • Liquefaction probability curves for Qts are developed in this study. • Liquefaction potential is over-predicted without a diagenesis correction factor. • A lower-bound average diagenesis correction factor for Qts is 1.11. [ABSTRACT FROM AUTHOR]

Explicit empirical relationships for correcting liquefaction resistance of unsaturated soil below the groundwater table using compression wave velocity () and shear wave velocity () are derived and evaluated in this paper. The relationships are derived using published laboratory test data for four different sands and one silt material. The laboratory test data based on exhibit less scatter than the test data based on the ratio . For this reason, the -based relationship is recommended for correcting the liquefaction resistance of unsaturated soil. The influence of loading cycles and relative density on the recommended relationship is investigated. From a review of 40 field case history sites, it is found that in the critical layers at 20% of the sites, average is less than 1,400 m/s, indicating unsaturated conditions. Liquefaction resistances computed for eight field case histories with in the critical layers are corrected and plotted on penetration- and -based liquefaction evaluation charts. The results support the use of the correction for unsaturated conditions below the groundwater table. [ABSTRACT FROM AUTHOR]

Liquefaction potential of four Pleistocene beach sand deposits in the Greater Charleston area, South Carolina, is assessed. The assessment is based on a review of 51 sites of conspicuous craterlets and horizontal ground displacement that occurred in beach sand deposits during the 1886 Charleston earthquake and an analysis of 82 seismic cone penetration tests with pore-pressure measurements. Of the 51 ground failure sites, 23 are associated with the Ten Mile Hill beds; 13 with the Wando Formation; 13 with the Silver Bluff terrace and younger deposits that lie adjacent to the harbor, rivers, and creeks; and two with the Ladson Formation. Liquefaction potential is analyzed using the seismic cone data with and without correction for age-related processes (diagenesis) and then expressed in terms of the liquefaction potential index (LPI). Probability curves are developed from the LPI calculations for different earthquake ground-shaking parameters. The probability curves for the Wando Formation overpredict liquefaction potential when no corrections for diagenesis are made. When corrections for diagenesis are made, the probability curves for all four sands generally agree with the observed field behavior. [ABSTRACT FROM AUTHOR]

Abstract: Liquefaction potential of aged soil deposits in Mount Pleasant, South Carolina, based on the 1886 Charleston earthquake is characterized in this paper. The characterization involves reviewing available first-hand accounts of 1886 ground behavior, analyzing cone penetration test (CPT) and shear wave velocity data, and correlating the results with geology. Careful review of the first-hand accounts reveals that nearly all cases of surface effects of liquefaction can be associated with the younger sand deposits that lie adjacent to the harbor, rivers, and creeks. Only one documented case of minimal surface effect of liquefaction can be definitely associated with the older sand deposits of the 100,000-year-old Wando Formation. Ratios of measured-to-estimated shear wave velocity indicate that the younger sand deposits and the older sand deposits have measured velocities that are 9% and 38%, respectively, greater than 6-year-old sand deposits with the same CPT tip resistance. Liquefaction potential is expressed in terms of the liquefaction potential index (LPI) proposed by Iwasaki and others. LPI values for the Wando sands computed from the CPT profiles are incorrectly high, if no age corrections are applied. If age corrections are applied, computed LPI values match well the observed field behavior in both the younger sands and the older sands. The results are combined with a 1:24,000 scale geologic map to produce a liquefaction potential map of Mount Pleasant. The findings of this study agree remarkably well with a previous liquefaction potential study of aged soil deposits on Charleston peninsula. [Copyright &y& Elsevier]

Data from over 30 sites in 5 countries are analyzed to develop updated factors for correcting liquefaction resistance for aged sand deposits. Results of cyclic laboratory tests on relatively undisturbed and reconstituted specimens suggest an increase in the correction factors of 0.12 per log cycle of time and an average reference age of 2 days for the reconstitute specimens. Laboratory and field test results combined with cyclic resistance ratio (CRR) charts suggest an increase in the correction factors of 0.13 per log cycle of time and an average reference age of 23 years. A reference age of 23 years seems appropriate for the commonly used CRR charts derived from field liquefaction and no liquefaction case history data. Because age of natural deposits is often difficult to accurately determine, a relationship between measured to estimated shear-wave velocity ratio (MEVR) and liquefaction resistance correction factor is also derived directly from the compiled data. This new MEVR-liquefaction resistance correction factor relationship is not as sensitive to MEVR as in the relationship derived indirectly in a previous paper. [ABSTRACT FROM AUTHOR]

Factors for correcting liquefaction resistance for aged sands using ratios of measured to estimated shear-wave velocity (MEVR) are derived in this paper. Estimated values of shear-wave velocity (VS) are computed for 91 penetration resistance-VS data pairs using previously published relationships. Linear regression is performed on values of MEVR and corresponding average age. Age of the sand layer is taken as the time between VS measurements and initial deposition or last critical disturbance. It is found that MEVR increases by a factor of about 0.08 per log cycle of time, and time equals about 6 years on average when MEVR equals 1 for the recommended penetration resistance-VS relationships. The resulting regression equation is combined with the strength gain equation reported by Hayati et al. 2008 in “Proc., Geotechnical Earthquake Engineering and Soil Dynamics IV,” to produce a MEVR versus deposit resistance correction relationship. This new corrective relationship is applied to create liquefaction resistance curves based on VS, standard penetration test blow count, and cone tip resistance for sands of various ages (or MEVRs). Because age of natural soil deposits is usually difficult to accurately determine, MEVR appears to be a promising alternative. [ABSTRACT FROM AUTHOR]

A liquefaction potential map of the peninsula of Charleston, S.C., is presented in this paper. Liquefaction potential is expressed in terms of the liquefaction potential index developed by Iwasaki et al. and calculated using 44 cone penetration test profiles. The cone profiles are supplemented with information from the 1:24,000 scale geologic map by Weems and Lemon, several first-hand accounts of liquefaction and ground deformation that occurred during the 1886 Charleston earthquake, and liquefaction probabilities determined by Elton and Hadj-Hamou based on standard penetration tests. Nearly all of the cases of liquefaction and ground deformation occurred in the Holocene to late Pleistocene beach deposits that flank the higher-ground sediments of the Wando Formation. To match the observed field behavior, a deposit resistance correction factor of 1.8 is applied to cyclic resistance ratios calculated for the 100,000-year-old Wando Formation. No corrections are needed for the younger deposits. In additional to 1886 field behavior, the deposit resistance corrections are supported by ratios of measured to predicted shear-wave velocity. [ABSTRACT FROM AUTHOR]

Model uncertainty associated with normalized shear modulus and material damping ratio relationships developed in a previous study is discussed in terms of standard deviations in this paper. The relationships were originally developed by separating resonant column and torsional shear test results of 122 specimens into three general geologic groups (Quaternary-age soils, Tertiary-age and older soils, and residual/saprolite soils) and determining mean regressional model parameters (i.e., α, k, γr1, and Dmin1) for each group. Statistical variability of the regressional parameters is quantified and expressed by standard errors of prediction. The determined uncertainty of the regressional parameters is then propagated through the recommended relationships using the point-estimate method to estimate the model uncertainty of the relationships. The point-estimate method is a simple and effective method of uncertainty propagation. For uncertainty estimation, the regressional parameters are assumed to be uncorrelated for the sake of simplicity. The influence of this assumption on the model uncertainty of normalized shear modulus and material damping ratio values, as well as the sensitivity of the model uncertainty to the uncertainty of various regressional parameters, are also discussed. [ABSTRACT FROM AUTHOR]

Predictive equations for estimating normalized shear modulus and material damping ratio of Quaternary, Tertiary and older, and residual/saprolite soils are presented in this paper. The equations are based on a modified hyperbolic model and a statistical analysis of existing Resonant Column and Torsional Shear test results for 122 specimens obtained from South Carolina, North Carolina, and Alabama. Variables used in the equations for normalized shear modulus are: shear-strain amplitude, confining stress, and plasticity index (PI). The equations for damping ratio are expressed in terms of a polynomial function of normalized shear modulus plus a minimum damping ratio. It is found that the Quaternary soils exhibit more linearity than soils of the other two groups. Also, it is found that the effect of PI on dynamic soil behavior is not as significant as previously thought. Data from all three groups exhibit significant variations with confining stress, similar to the variations determined by Stokoe et al. The uncertainties associated with the equations for PI of 0 and mean effective confining stress of 100 kPa are quantified using the point estimate method. A case study from Charleston, S.C. is provided to illustrate an application of the equations to seismic response analysis and the importance of considering confining stress and geologic age. [ABSTRACT FROM AUTHOR]

Three methods that follow the general format of the Seed-Idriss simplified procedure for evaluating liquefaction resistance of soils are compared in this paper. They are compared by constructing relationships between penetration resistance and small-strain shear–wave velocity (VS) implied from cyclic resistance ratio (CRR) curves for the three methods, and by plotting penetration-VS data pairs. The penetration-VS data pairs are from 43 Holocene-age sand layers in California, South Carolina, Canada, and Japan. It is shown that the VS-based CRR curve is more conservative than CRR curves based on the Standard Penetration Test (SPT) and Cone Penetration Test (CPT), for the compiled Holocene data. This result agrees with the findings of a recent probability study where the SPT-, CPT-, and VS-based CRR curves were characterized as curves with average probability of liquefaction of 31, 50, and 26%, respectively. New SPT- and CPT-based CRR equations are proposed that provide more consistent assessments of liquefaction potential for the Holocene sand layers considered. [Copyright &y& Elsevier]

Presents a simplified procedure using shear-wave velocity measurements for evaluating the liquefaction resistance of soils. Calculation of different parameters; Previous shear-wave velocity measurements conducted; Details on the process of developing the liquefaction evaluation chart; Conclusions.

A review of the current state of the art in the assessment of aging effects on soil liquefaction is presented in this paper. The review includes a summary of several field case histories indicating greater resistance to liquefaction in aged soils than in young uncemented soils during earthquakes, a discussion of the mechanisms that increase liquefaction resistance with time, an evaluation of proposed methods for quantifying the influence of aging processes (or diagenesis) on liquefaction resistance (K DR), and an evaluation of proposed predictor variables for K DR. The published literature indicates physical diagenetic processes tend to dominate the nature of interactions at the grain-to-grain contacts of sand deposits in the absence of sufficient cementing agents, while chemical processes tend to dominate where sufficient cementing agents are present. Variables proposed for predicting K DR include: the time since deposition or last critical disturbance; the ratio of measured to estimated small-strain shear wave velocity (MEVR); the ratio of small-strain shear modulus to cone tip resistance (G max /q c); the adjusted G max /q c (K G); and the ratio of measured to estimated adjusted G max /q c (MEK G). It is shown that MEVR , G max /q c , K G and MEK G are all ratios of measured to estimated or reference shear wave velocity. MEVR and G max /q c are slightly more robust predictors (i.e., regression equations with higher coefficient of regression and lower root mean square error) of K DR than K G and MEK G. Time is the least robust predictor of K DR. • Aging changes the soil's structure and liquefaction resistance with time. • Aging can be predicted using time, MEVR , G max /q c , K G or MEK G. • MEVR , G max /q c , K G or MEK G are ratios of measured to estimated or reference velocity. • MEVR and G max /q c are slightly more robust predictors of aging. • Time is the least robust predictor of aging. [ABSTRACT FROM AUTHOR]

It is imperative that water supply networks (WSNs) continue to perform even after subjected to natural and anthropogenic hazards, and it is even more important in the case of earthquakes for fighting fires that usually follow. Past earthquakes have caused significant damage to WSNs rendering them dysfunctional and potentially threatening human survival. Although there has been a lot of research conducted in the past on the behavior of buried pipelines, there are few metrics and models that are readily usable for improving the performance of large WSNs prone to seismic hazards. This paper proposes an easy-to-use metric for quantifying resilience and an optimization framework for improving WSN resilience subjected to budgetary constraints. The proposed resilience metric is dependent on hazard intensity, estimated pipeline response, and network topology. The use of the proposed metric and the optimization framework are demonstrated on a large (1,874 pipelines and 1,474 demand nodes), real-world WSN in a coastal region prone to earthquakes. The resilience value of the existing WSN used for demonstration is found to increase by approximately 8% with a $10 million investment. The proposed metric and the optimization framework can be helpful in rehabilitation planning and capital improvement works by water utilities. [ABSTRACT FROM AUTHOR]

The Cooper marl in Charleston, S.C., a deep layer of clayey soils approximately 5–21 m below the ground surface, is generally recognized as nonliquefiable material. Data from field cone penetration tests and laboratory tests of samples taken from the Cooper marl are used to investigate the adequacy of index properties-based criteria for assessing liquefaction susceptibility of clayey soils. In particular, the criterion based on soil behavior type index (Ic) and that based on Atterberg limits are examined. The results show that the Atterberg limits-based criterion adequately reflected the characteristics of the marl, whereas the Ic-based criterion erroneously identified the marl as being liquefiable. A possible reason for the deficiency of Ic and a modification to overcome this deficiency are presented. [ABSTRACT FROM AUTHOR]

The 1999 Chi-Chi, Taiwan earthquake caused great destruction to buildings, bridges, and other facilities, and a death toll of more than 2400. Lessons should be learned from this event, which, albeit disastrous, represents a rare full-scale experimentation in geotechnical engineering and related fields. Of particular interest to geotechnical engineers is the phenomenon of soil liquefaction that caused significant damage to buildings, lifelines and harbor facilities. These liquefaction phenomena, in the forms of sand boils, lateral spreads, tilting and settlement of buildings, and ground settlement, were observed in the Chi-Chi event. Shortly after the earthquake, an extensive field investigation in the Yuanlin area, including in situ tests and laboratory tests, was conducted by Moh and Associates and other parties. These in situ and laboratory tests along with ground performance observations form the basis for the present study.In this paper, 24 cases of ground performance in the areas that suffered the most from liquefaction are studied. The ground performance in selected cases of the 24 cases is accounted for through a series of liquefaction analyses. The analysis of the potential of liquefaction and ground failure is performed using Cone Penetration Test (CPT) data. The results of the analyses show that the field observations of ground performance in the Yuanlin area in the Chi-Chi event can be accounted for satisfactorily using the evaluation procedure by Ishihara (Ishihara, K., 1985. Stability of natural deposits during earthquakes. Proc., 11th Int. Conf. on Soil Mechanics and Foundation Engineering, San Francisco, CA, vol. 1, pp. 321–376.). [Copyright &y& Elsevier]

This paper presents an assessment of existing and new probabilistic methods for liquefaction potential evaluation. Emphasis is placed on comparison of probabilities of liquefaction calculated with two different approaches, logistic regression and Bayesian mapping. Logistic regression is a well-established statistical procedure, whereas Bayesian mapping is a relatively new application of the Bayes’ theorem to the evaluation of soil liquefaction. In the present study, simplified procedures for soil liquefaction evaluation, including the Seed–Idriss, Robertson–Wride, and Andrus–Stokoe methods, based on the standard penetration test, cone penetration test, and shear wave velocity measurement, respectively, are used as the basis for developing Bayesian mapping functions. The present study shows that the Bayesian mapping approach is preferred over the logistic regression approach for estimating the site-specific probability of liquefaction, although both methods yield comparable probabilities. The paper also compares the three simplified methods in the context of probability of liquefaction, and argues for the use of probability-based procedures for evaluating liquefaction potential. [ABSTRACT FROM AUTHOR]

Responds to comments on an article regarding liquefaction resistance of soils, published in a previous issue of the 'Journal of Geotechnical and Geoenvironmental Engineering.' Geologic setting; Consequences of liquefaction; Overly conservative proclivity of the simplified procedure.