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A new approach based on the limit equilibrium method to calculate the ultimate bearing capacity of a strip shallow foundation is presented in this paper. The bearing capacity estimated with Terzaghi's three-term basic formula using the superposition method has proven to be conservative. A proposed failure mechanism to determine the bearing capacity coefficients of the three parameters, namely, the cohesion (Nc), the surface surcharge (Nq) and the soil weight (Nγ), is developed. The 'individual minimum' of each coefficient is determined using different failure mechanisms; hence, a new analytical approximation is suggested for calculating the 'global minimum' of the bearing capacity with a single failure mechanism without superposition. The rationality of the results of the analytical solutions (bearing capacity and failure mechanism) is verified using finite element analysis with the program PLAXIS 2D and kinematical analysis with the program FIDES-GeoStability. [ABSTRACT FROM AUTHOR]

This study investigates the effectiveness of a vertical trench in mitigating the hazards associated with reverse faulting on shallow foundations and assesses the accuracy of analytical relations for estimating the required trench depth through numerical analyses. Results show that a trench near a foundation diverts the fault rupture away from the building. Increasing the trench depth and width, positioning it closer to the foundation, and increasing the structure weight significantly increase the fault rupture diversion probability, reducing foundation damage level. Moving the foundation towards the hanging wall decreases rupture diversion probability. Trenches are more effective at smaller fault-dip angles. Narrower foundations with deeper alluvium require shallower trenches to minimize foundation damage. Existing analytical relations estimate trench depth with reasonable accuracy to divert fault rupture and minimize structural damage. [ABSTRACT FROM AUTHOR]

The present study focuses on estimating the transient response of shallow strip footing on granular soil using soft computing techniques. A shallow foundation is numerically modelled using Beam on Nonlinear Winkler Foundation model. Then the footing is subjected to a combination of allowable static and cyclic load depending on the ultimate bearing capacity of the footing. The eccentricity and angle of load inclination of static load are varied to simulate more practical conditions. The cyclic load is rectangular pulse load. One cycle of rectangular pulse load is applied to observe the immediate response of the foundation, referred as the transient response. Apart from the loading parameters, three granular soils of three different relative densities (Dr = 35%, 51% and 69%) are considered. Based on numerical simulation of 1728 conditions, soft computing models are developed using five techniques, viz. Neural Networks, Support Vector Machines, Multivariate Adaptive Regression Splines, Adaptive Neuro Fuzzy Interface System and Multi Gene Genetic Programming. It is found that the static load on the foundation is the most important parameter controlling the transient response of the footing. [ABSTRACT FROM AUTHOR]

The paper analyses in detail and compares different interpretation procedures of snap-back and forced-vibration tests on a full-scale prototype founded on soft-soil, in order to assess their effectiveness for measuring the stiffness and damping of a shallow foundation under dynamic loads. Both properties were back-calculated through three alternative methods, i.e. through impedance functions computed in the frequency domain, or by interpreting force-displacement loops in terms of peak-to-peak amplitudes or of phase-shift. The damping was further calculated from the logarithmic decrement of free-vibration records. The resulting foundation stiffness and damping were observed to vary with the number of cycles and with the load frequency and amplitude. The comparison among the interpretation techniques revealed that the peak-to-peak approach fails when damping is high, because it neglects the delay between force and displacement. [ABSTRACT FROM AUTHOR]

Stone columns are widely used around the world as cost-effective soil improvement techniques for highways and embankments. They are also used as drainage to expedite the consolidation period, and accordingly to increase the allowable pressure, reduce settlement, and reduce the liquefaction potential for shallow foundations. Currently the design of these columns is based on the unit cell or homogenised material concepts, which neglect the effect of the interaction of the columns. This paper presents a 3-D numerical model using the finite element technique and the commercial software 'ABAQUS' to simulate the case of a group of stone columns installed in soft clay. The model is capable of capturing the interaction between columns and the surrounding soil and of establishing the mode of failure of the system. After validating the model with the available experimental results, it was used to predict the allowable pressure and the failure mechanism of groups of stone columns for given geometry/soil conditions. An improvement factor was introduced 'IF', which is defined as the ratio of the capacity of the improved to the unimproved soft clay. The results of this investigation are presented in the form of design charts to assist the engineer to determine the level of improvement needed to achieve a given allowable pressure for the foundation. [ABSTRACT FROM AUTHOR]

This paper presents three-dimensional finite element analyses conducted to optimise the instrumentation plan for monitoring the structural performance of reinforced concrete three-sided culverts (TSCs). Numerical models were developed for three TSCs with spans of 7.3, 10.4, and 13.5 m to establish the anticipated range of measurements. The TSCs were instrumented with 30 pressure cells and 56 strain gauges. Comparing the numerical predictions with field measurements of the 10.4-m-span TSC verified the adequacy of simulating the concrete behaviour as linear elastic for estimating the applied earth pressures. However, such simplification would lead to underestimating the induced strains in the culvert body in case cracks develop. In addition, Class-A predictions of soil pressures on the culvert were compared with the field measurements of a 7.3-m-span TSC. The calculated soil pressures agreed well with the field measurements. The measured and calculated earth pressures suggest a vertical arching factor of 1.05 at the final backfill height. The influence of the shallow foundation geometry was investigated employing the validated numerical model. It was found that the footing geometry has no influence on the applied earth pressures. However, the calculated stresses below the footing edge on the backfill side decreased as the footing flexibility increased. [ABSTRACT FROM AUTHOR]

Due to the shortage of urban land, new buildings are constructed adjacent to old buildings. In this regard, there is limited information about the behaviour of the shallow foundations adjacent to the excavation. In this research, a series of experimental and numerical studies are conducted on reinforced and unreinforced granular soils adjacent to excavation loaded with square footings. The experimental results are in good agreement with the numerical study. Numerical investigations were carried out on sandy excavation by varying the footing distance from the edge of the different granular excavations. It was found that by using three reinforcing layers, the ultimate bearing capacity would increase. Additionally, excavation has no significant effect in the vicinity of 4B, in which B is the footing width. Furthermore, the need to build new large buildings in the vicinity of each other has reduced the distances between square footings and, as a result, has created the phenomenon of interference in the footings and excavation. This occurs through the interference of wedges and rupture surfaces. Since this phenomenon bears a substantial result on the bearing capacity of shallow footings, this work investigates the effect of interference of ruptured wedges on the carriage capacity, settlement, and deformation of square footings. The optimum interference factor is defined at spacings of 2B and 3B for dense and loose reinforced sands, respectively. Furthermore, by including three continuous geogrid layers underneath two square footing interferences, their behaviour will be improved. [ABSTRACT FROM AUTHOR]

The efficiency of polyester and bamboo geogrids in reducing the seismic settlement of low-rise buildings has been investigated in this paper. A series of shake table experiments was carried out for this purpose. It was observed that the beneficial attributes of a rocking foundations in reducing the flexural deformation and column moment remained unchanged after inclusion of geogrids. However, the settlement, a primary adverse consequence of a rocking foundation, reduced significantly (as much as 70–75%). In a developing country like India, natural material-like bamboo threads combined with geo-polymers may be utilized for safe and sustainable seismic design. [ABSTRACT FROM AUTHOR]

This study investigates the bearing capacity of strip footings resting on unsaturated soils subjected to combined loading using the lower-bound limit analysis coupled with the finite element discretization approach. In this regard, second-order cone programming (SOCP) is exploited to simulate the nonlinear form of the universal Mohr-Coulomb yield criterion during the process of stress field optimization. The significant influence of matric suction induced below the surface footing was accounted for by adopting the suction stress concept under the no-flow and steady-state infiltration/evaporation flow conditions. The eccentricity and inclination of the foundation loading are introduced into the equilibrium equations along the strip footing so as to render various combinations of moment (M), vertical (V) and shear (H) forces. The results stemming from the lower-bound finite element limit analysis are compared with several previous studies throughout the literature for verification of the model. The substantial contribution of suction stress to the evolution of failure loci and the distribution of subsurface stresses for the shallow foundation subjected to inclined and eccentric loadings is thoroughly discussed. A general three-dimensional failure envelope is presented for shallow foundations resting on partially saturated soils under combined vertical, horizontal and moment loadings. [ABSTRACT FROM AUTHOR]

Using plate load test to evaluate the scale effects of shallow foundation bearing capacity on geogrid-reinforced sand is expensive because large boxes need to be built, and the devices to apply the loads to the reinforced soil are complex. Consequently, the finite element method is an alternative to investigate this phenomenon. In this study, a series of 3D axi-symmetry finite element models were developed to study the scale effect on the bearing capacity of circular footings resting on geogrid-reinforced sand. First, a 100 mm-diameter circular foundation supported by geogrid-reinforced sand was simulated in order to validate the finite element model with laboratory tests. Subsequently, different models were made by increasing the diameter of the foundation and the diameter of the geogrid in the same proportion. Modelling results indicated that as the foundation diameter increased, the bearing capacity of unreinforced and reinforced soil decreased. Likewise, the benefit obtained from the reinforcement was less when the model size was increased. [ABSTRACT FROM AUTHOR]

Present study investigates the upper bound bearing capacity of a shallow strip foundation on unsaturated fly ash slope overlying clayey deposit through finite element limit analyses incorporating suction stress based engineering parameters. Study has been conducted to incorporate uncertainties in the critical parameters including water retention characteristics curve (WRCC) parameters on the overall bearing capacity under a probabilistic framework through factorial design methodology. Relative significance of uncertain parameters has been quantified and a prediction model has been developed through multiple regression analysis. Probability of failure of a shallow footing, resting near a fly ash slope, has further been evaluated using Monte-Carlo (MC) simulation technique. [ABSTRACT FROM AUTHOR]

Geocell reinforcement (GR) improves load-deformation behavior of shallow foundations. A series of instrumented large-scale plate load tests was performed to ascertain such improvements and to correlate that to the relative density (Dr) of geocell-reinforced sand (GRS). Variable effects on stiffness, bearing capacity (BC), load dispersion and strain-stress behaviors are discussed. The extensive tests made it possible to arrive at a simplified analytical procedure for predicting the BC of circular footings on GRS, taking into account probable shear failure mechanisms and monitored GR deformation. These results allowed the validation and generalization of the procedure reduced from an equivalent-layer BC model considering 'confinement' and 'stress dispersion' effects on the failure mechanism. Load dispersion angle and strains increase with increasing the sand Dr resulted in significant stress reduction below the GR. This was found most beneficial for the higher densities ranges. The proposed analytical approach can confidently be used for practical design purposes. [ABSTRACT FROM AUTHOR]

In the present study, the behaviour of a shallow rectangular foundation placed over the multiple layers of the geogrid reinforced sand under eccentric and oblique loads in both dimensions was studied. Various parameters were investigated in this study including the number of reinforced layers (N), eccentricity (e/B, e/L) and inclination of applied load (α). Bi-axial geogrid (Bx20/20)-reinforced sand and laboratory results were compared with PLAXIS 3D software keeping N, eccentricity ratios and angle of inclination as input parameters. The results present that the value of Ultimate Bearing Capacity (UBC) of model foundation found reduced as the axial eccentricity and inclination of applied loads increased. It also found that multiple geogrid-reinforced layers increased the UBC of about 75%. Finally, the model test results were analysed using PLAXIS 3D. A good agreement was originated between the laboratory results and numerical analysis. [ABSTRACT FROM AUTHOR]

This paper presents a multiscale approach to analyse the seismic response of a spread-footing system founded on saturated granular soil deposits that might be susceptible to liquefaction. The pore-fluid is idealised as a continuum by using a homogenised form of Navier-Stokes equations that accounts for the presence of the solid particles. These particles are modelled at a microscale using the discrete element method. The foundation is idealised as a square rigid block by generating a group of glued particles. Computational simulations were conducted to investigate the response of spread-footings on saturated deposits when subjected to a seismic excitation. For the considered closely-spaced foundation system, it is possible to have a foundation settlement smaller than the free-field. Stress overlap between neighbouring footings could lead to an increase in soil stiffness and less susceptibility to pore-pressure build-up and volume decrease compared with the free-field. The majority of the foundation settlement occurs during shaking, whereas settlement continues to accumulate post shaking in the free-field. Evaluation of the contribution of base and lateral walls of the foundation to the lateral response of the footing showed that the predominant contributors were the base shear force and walls normal to the direction of shaking. [ABSTRACT FROM AUTHOR]

Design of shallow foundations subjected to dynamic loading is an important topic in the geotechnical engineering practice. In this study, an attempt has been made to evaluate the seismic bearing capacity of a strip footing founded on a soil deposit using the lower bound limit analysis method merged with the finite element formulation adopting the second-order conic programming (SOCP) approach. To this end, a well-established pseudo-dynamic loading scheme has been employed to apply the seismic loading on the surface footing. Accounting for the various conditions of the underlying soil layer, the results of the so-called 'conventional pseudo-dynamic (CPD)', 'spectral pseudo-dynamic (SPD)' and 'modified pseudo-dynamic (MPD)' bearing capacity analyses are compared with one another and their pseudo-static counterparts in terms of the value of N γ parameter. The results show the notable influence of the amplification factor, the impedance factor and the site characteristics on the seismic bearing capacity of shallow foundations. In addition, the results obtained from the MPD, CPD and SPD methods are observed to bear a good agreement with each other. Moreover, the MPD approach was observed to render the most conservative seismic bearing capacity values. [ABSTRACT FROM AUTHOR]

Reinforced Concrete (RC) frame buildings with shear wall are widely used in severe seismic zones. However, the underlying soil-foundation system modifies the conventional fixed-base natural period through imparted flexibility. The currently available relationships for the modified natural period are mostly applicable to shallow foundations. Hence, those are not suitable for RC frame-wall buildings with pile foundation. Based on an Artificial Neural Network (ANN) architecture model, the current study establishes a relationship for the effective natural period of such buildings. A comparison of the proposed relationship with the existing ones demonstrates its applicability to RC frame-wall buildings on pile foundation. [ABSTRACT FROM AUTHOR]

Assessment of liquefiable soils strength is a challenging task in engineering practice especially when a structure is founded on top of the liquefied soil. While it has been addressed and studied in the literature, the lack of practically feasible approaches to calculate the bearing capacity of soil in such a condition is tangible. In this study, simple analytical equations have been proposed to calculate the bearing capacity of liquefiable soils under shallow foundations. The equations have been developed for two cases, separated based on the thickness of liquefiable soils and width of foundation, each of which acting with different mechanisms. The proposed approach was evaluated versus field observations from the 1964 Niigata, the 1990 Luzon, and the 1999 Adapazari earthquakes, in addition to an assessment against numerical simulations. It was shown that the methodology is capable of estimating the bearing capacity of liquefiable soils under shallow foundations. The obtained results reveal that decreasing the thickness of the liquefiable layer as well as increasing foundation width leads to a higher bearing capacity. Finally, an easy to use design charts and simple equations have been derived for use in engineering practice. [ABSTRACT FROM AUTHOR]

To assess the dynamic stiffness of shallow foundations, as an alternative to the existing rigorous approaches, it is convenient to idealize the soil as some semifinite truncated cones representing the infinite nature of the supporting soil. The one-dimensional wave equation for cones which is usually defined in frequency domain has been extended to be solved directly in the time domain. The recently streamlined strength of materials using cones has been developed in the time domain to calculate the response of shallow foundations on a layered half-space for translational degrees of freedom, while the wave pattern in the time domain is not studied for a rocking degree of freedom. The concept of echoes which converts the response of the footing on homogenous half-space to that of the footing on layered site is still applicable when the layered system excited by rocking moments. The echo constants are derived in the current research for rotational degrees of freedom in either the flexibility or stiffness formulation. In this paper, using the theory of cones, equations for direct analysis of soil-structure interaction in the time domain are obtained for the rocking degrees of freedom. The results, calculated exclusively in the familiar time domain, are in remarkable agreement with the results obtained in the frequency domain. [ABSTRACT FROM AUTHOR]

The bearing capacity of shallow foundations on rocks under inclined and eccentric loads is investigated using the kinematic approach of limit analysis theory. The study focuses on evaluating the reduction of bearing capacity induced by the eccentricity and the inclination of the load with respect to the vertical direction. The generalized Hoek and Brown criterion is adopted to describe the strength properties of the rock. A failure mechanism is used to implement the kinematic approach of limit analysis. This study provides an upper bound of the bearing capacity of the strip footing. Comparisons were made between the results of this approach and those obtained using finite element limit analysis. These comparisons confirm the accuracy of the proposed approach. Finally, a parametric study was carried out, which evaluated the effects of geometric, strength and loading parameters on the bearing capacity of the strip footing. [ABSTRACT FROM AUTHOR]

Bearing capacity degradation in shallow foundations due to subsoil liquefaction is not a new challenge in earthquake geotechnical engineering. Thus far, limited mitigation measures against this problem were suggested in the literature. In this paper, mitigation of liquefaction-induced bearing capacity degradation of shallow foundations using Deep Soil Mixing (DSM) method was investigated numerically. A 3D finite difference model has been developed via FLAC3D. It was explored whether liquefaction effects on static and seismic bearing capacity of shallow foundations were diminished, and may be effectively overlooked, for DSM column diameter and length and also shallow foundation width variation. It was found that an artificial non-liquefiable soil layer made by DSM method improves the seismic bearing capacity of shallow foundations remarkably. Therefore, in terms of excess pore water pressure generation decreases and bearing capacity ratio increases. It was also concluded that by increasing the diameter and length of the DSM columns, the seismic bearing capacity of shallow foundations increases. However, as shallow foundation width increases, along with an increase in DSM column diameter and length, the performance of DSM columns and accordingly shallow foundation decreases. [ABSTRACT FROM AUTHOR]

This paper proposes a new hybrid artificial neural network and mathematical (ANN-MATH) model to improve the prediction capability of the load-settlement behaviour of shallow foundations in sandy soils. The hybridisation process is performed by replacing the conventional activation function of the ANN output layer by a new mathematical model. Thereafter, 110 full-scale loading tests of shallow foundations, carried out in sand with the cone penetration test (CPT) results, are used to build and validate the proposed model. In terms of accuracy, the proposed model shows a high correlation between the predicted results and the measured data. In addition, the proposed method was compared to the available methods in the literature. It was found that the proposed model is superior to classical and artificial intelligence-based methods by more than 29% and 35%, respectively, in terms of root mean square error (RMSE). Furthermore, a parametric study was undertaken to assess the robustness of the proposed model and to derive the bearing capacity factor based on the CPT test. The bearing capacity factor was found close to those recommended by the French standard NF P 94–261. [ABSTRACT FROM AUTHOR]

The major objective of this paper is to investigate the seismic behavior of bridge-deck-pier-foundation type structures incorporating both structural and soil yielding using a realistic computational model. The model, developed in OpenSees finite element framework, was calibrated and validated using experimental results. Several numerical simulations were carried out to analyze the behavior of fixed-base and rocking foundation systems under realistic earthquake shakings. The study found that incorporating rocking foundation design reduces the peak deck drift due to flexure, peak acceleration on the deck, and the column base shear and moment by more than 50% when compared to fixed-base design. [ABSTRACT FROM AUTHOR]

This research explores the effectiveness of the use of stiff diaphragm walls next to a rocking foundation through numerical simulation. This improvement technique is used as a means to increase in subsoil peripheral confinement and reduce rocking-induced settlement. The numerical model was verified by the centrifuge test of rocking shallow foundations on clay under cyclic loading. A parametric study was conducted to explore the effect of three stiff wall shapes on the performance of a rocking system. The general conclusion of the parametric investigation is that the use of stiff diaphragm walls reduced the sinking-dominated settlement response of the rocking system. [ABSTRACT FROM AUTHOR]

The present study proposes reliability-based approach for assessing the performance of shallow foundation placed in the vicinity of an existing buried flexible pipe or utility tunnel. Performance function for the reliability analysis is defined in terms of % bearing capacity loss in the load carrying capacity of the shallow foundation due to the presence of buried flexible pipe or utility tunnel, and, allowable bearing capacity loss in load carrying capacity that can be tolerated. For the reliability analysis, an explicit functional relationship between input variables, such as geotechnical parameters of in situ soil as well as material properties of pipe, and, output response, i.e. % bearing capacity loss in load carrying capacity of foundation soil is needed. Using concept of response surface methodology (RSM) combined with the results of the numerical analysis; such an explicit functional relationship is easily established. Thereafter, reliability analysis can be performed, conveniently, using standard First Order Second Moment (FOSM) approach and performance of the foundation soil system with buried flexible pipe, present in the vicinity, can be assessed in terms of an index, popularly known as 'reliability index (β)'. [ABSTRACT FROM AUTHOR]

Based on a new elasto-plastic constitutive model, this paper presents a soil–water coupled numerical prediction of the bearing capacity for shallow foundation constructed on Ballina soft clay for unconsolidated undrained (UU) and consolidated undrained (CU) conditions. This elasto-plastic constitutive Shanghai model has an advantage of describing the mechanical behaviour of over-consolidated and structured soil under different loading and drainage conditions, by using one set of material parameter. In this paper, the Shanghai model used for both UU and CU conditions has the same initial parameters obtained from laboratory test results. The loading conditions and consolidation stages vary based on construction details. The predicted bearing pressure-settlement responses for UU and CU, approves the field observation. The phenomenon of gaining the bearing capacity due to consolidation is captured and explained by the use of soil–water coupled numerical analysis with a new elasto-plastic model. The stress strain behaviour, stress paths and the decay of the structure of elements at different depths presented in this study, reveal the mechanism for the difference between UU and CU conditions to understand the foundation behaviour. Effect of the initial degree of soil structure on the bearing capacity is also addressed. Overall, this approach provides the integrated solution for the shallow foundation design problems under short and long-term loadings. [ABSTRACT FROM AUTHOR]

By application of the limit equilibrium method associated with Coulomb failure mechanism, the effect of variation of undrained shear strength with depth on seismic bearing capacity was evaluated. The approach followed in this study to take into account seismic forces is pseudo-static. It is also assumed that the occurrence of an earthquake does not have any effects on the values of soil cohesion. Two different marine soil deposits exhibiting linear and bilinear variations of undrained shear strength with depth were considered. The undrained bearing capacity factor has been computed as a function of dimensionless parameters of λ1B/c0, λ2B/c0, and Zt/B. The results of this paper have been compared with solutions reported in the literature, and the consistency of the results confirmed the ability of Coulomb failure mechanism and its corresponding limit equilibrium method formulation in static condition. Furthermore, the pseudo-static bearing capacity of shallow foundations on heterogeneous marine deposit is addressed. Finally the results of this study presented in the form of table and design charts. [ABSTRACT FROM AUTHOR]

The limit equilibrium method with a multi-block failure mechanism has been utilised to study and estimate the bearing capacity of shallow foundations on anisotropic deposits. The multi-block mechanisms of Hill and Prandtl types were adapted to consider the effect of the footing–soil interface roughness. Both mechanisms composed of passive and active wedges and multiple transitional blocks between them. As an anisotropic medium, the soil shear strength parameters were considered to entail a linear relationship with the bedding plane orientation. The dependency of the soil shear strength parameters to the depositional characteristics renders the problem to be highly nonlinear and hence, an iterative procedure was adopted to achieve a converged and optimal bearing capacity estimation. The optimisation was made by the Genetic Algorithm (GA) in an iterative process. Bearing capacity of isotropic soils was also calculated as a benchmark solution and then, extended to anisotropic soils. Some correction factors for three bearing capacity terms have been presented which cover a wide range of the anisotropy ratio. In general, the shear strength anisotropy proved to decrease the bearing capacity of a shallow foundation. The results were compared with some experimental and numerical results. [ABSTRACT FROM AUTHOR]

This work was aimed at developing a practical and simple settlement estimation of shallow foundation on liquefiable deposits. The study conducted a centrifuge test, a series of comprehensive numerical analysis, back analysis, equation calibration, and verification with data from not only centrifuge test but also the literature. It finally proposed a quick calculation method based on Meyerhof’s settlement equation (1965). A two-dimensional numerical analysis, named ALID, (Analysis for Liquefaction-induced Deformation), was employed for obtaining settlement of shallow foundations on liquefiable soils with different relative densities under various seismic conditions. Its performance was first verified through a centrifuge test conducted in this study. Then, the developed method based on Meyerhof’s settlement equation was employed, and a new parameter, NLR,was proposed to present the strength of liquefied soils by replacing N value in the original equation. The NLRwas obtained through back analysis of the numerical results and modified accordingly after comparison with the data from the literature. This paper, finally, demonstrated the practical use of the proposed method involving NLRby predicting 199 sets of liquefaction-induced settlement of shallow foundation reported in the past, including a latest most liquefaction-induced settlement of a house in 0206 earthquake on February 6, 2016, in Taiwan. [ABSTRACT FROM PUBLISHER]

In this study, a synthetic soil mixture has been developed and proposed for experimental soil-structure interaction shaking table tests on building frames with shallow foundations resting on soft soil deposits. The proposed mix provides adequate undrained shear strength to mobilise the required shallow foundation bearing capacity underneath the structural model while meeting both criteria of dynamic similarity between the model and the prototype to model soft soils in shaking table tests. To find the most appropriate mixture, different mixes with different proportions of mix components were examined in the soils laboratory. Performing bender element tests, the shear wave velocity of the soil specimens was acquired at different cure ages and the results were examined and compared. Based on the test results, a synthetic clay mixture consisting of kaolinite clay, bentonite, fly ash, lime and water has been proposed for experimental shaking table tests. [ABSTRACT FROM PUBLISHER]

Traditionally, shallow spread footing-type foundations are used for medium span bridges supported on hard soil and rock strata. Such bridges are modelled with fixed supports and no soil–foundation–structure interaction (SSI) is normally considered. The investigation presented herein utilized a sub-structuring technique and finite element method (FEM) model for the analysis of a four-span bridge designed for five different rock classes and subjected to an ensemble of actual ground motions. SSI was incorporated through Winkler springs while non-linear behaviour of reinforced concrete pier column was modelled by an equivalent linear model. The results of the study were evaluated to delineate the effect of SSI and pier column non-linearity on seismic response parameters of bridges founded on rock. It was found that the soil–foundation–structure interaction couldn’t be neglected in all cases of rock classes and input ground motions. Furthermore, pier column non-linearity influenced bridge displacement and base shear more significantly than SSI. Impact of foundation rocking was also examined and was found to be rather insignificant on bridge response parameters due to high rocking impedance of properly designed bridge foundations. [ABSTRACT FROM AUTHOR]

In this paper, the feasibility of using evolutionary computing for solving some complex problems in geotechnical engineering is investigated. The paper presents a relatively new technique, i.e. evolutionary polynomial regression (EPR), for modelling three practical applications in geotechnical engineering including the settlement of shallow foundations on cohesionless soils, pullout capacity of small ground anchors and ultimate bearing capacity of pile foundations. The prediction results from the proposed EPR models are compared with those obtained from artificial neural network (ANN) models previously developed by the author, as well as some of the most commonly available methods. The results indicate that the proposed EPR models agree well with (or better than) the ANN models and significantly outperform the other existing methods. The advantage of EPR technique over ANNs is that EPR generates transparent and well-structured models in the form of simple and easy-to-use hand calculation formulae that can be readily used by practising engineers. [ABSTRACT FROM PUBLISHER]

In the present investigation, the interaction between two nearby surface circular footings are determined by conducting a number of laboratory scaled model tests on a dry, cohesionless Ennore sand bed. The load-settlement curves for closely spaced circular footings of different sizes are obtained to study the interference effect between two footings. The effect of clear spacing (S) between the footings on the bearing capacity and settlement of interacting footings is studied. The experimental study indicates that the bearing capacity of single isolated footing on double layer soil deposit decreases with increase in the depth of top weak layer. A significant change in the bearing capacity and settlement of the interfering footing is observed in single as well as double layer soil deposit. Irrespective of the type of deposit, the ultimate bearing capacity of interfering footing increases with the decrease in the spacing between the footings. The settlement behaviour of the interfering footing at the ultimate failure is also studied, which follows the same trend as the bearing capacity. Finally, the results in term of efficiency factors (ξγ,ξδ) are presented and their variation is computed with respect to the change in the clear spacing (S) between two footings. The present experimental observations are compared with the results available in the literature. [ABSTRACT FROM PUBLISHER]

To date, a significant research effort has been devoted attempting to introduce novel seismic protection schemes, taking advantage of mobilization of inelastic foundation response. According to such an emerging seismic design concept, termed “rocking isolation,” instead of over-designing the footings of a frame (as in conventional capacity design), they are intentionally under-designed to promote uplifting and respond to strong seismic shaking through rocking, thus bounding the inertia forces transmitted to the superstructure. Recent research has demonstrated the potential effectiveness of rocking isolation for the seismic protection of frame structures, using a simple 1-bay frame as an illustrative example. This article: (a) sheds light in the possible limitations of rocking isolation, especially in view of the unavoidable uncertainties regarding the estimation of soil properties; (b) investigates the potential detrimental effects of ground motion characteristics; and (c) assesses the effectiveness of rocking isolation to more complex structures. It is shown that the concept may be generalized to 2-bay frames, and that even when foundation rocking is limited, the positive effect of foundation under-design remains, especially when it comes to very strong seismic shaking. In contrast, its effectiveness may be limited when the frame is subjected to combined horizontal and synchronous vertical acceleration components — a possible scenario on the surface of alluvial basins. [ABSTRACT FROM PUBLISHER]

Calibrated Finite Element (FE) simulations are increasingly providing a reliable environment for modelling liquefaction-induced ground deformation. Effects on foundations and super-structures may be assessed and associated remediation techniques may be explored, within a unified framework. Current capabilities of such a FE framework are demonstrated via a simple 3-dimensional (3D) series of simulations. Ground liquefaction and settlement under the action of a surface load is investigated. Liquefaction hazard mitigation is explored by soil compaction and/or increase of permeability below and around the applied surface load. The potential and limitations of numerical simulation are discussed, along with future research needs and challenges towards more reliable practical application. [ABSTRACT FROM AUTHOR]