Seismic Active Earth Pressure Research Articles

Seismic analysis of 3D active earth pressure for unsaturated backfill

A new procedure is proposed for evaluating active earth pressure subjected to earthquake vibration for three-dimensional (3D) unsaturated backfills comprised of cohesive soils, which is conducted by developing an upper bound analysis. The impact of diverse water tables on unsaturated soil-wall stability is incorporated into the comprehensive analysis, and it turns out to be indirect by exerting influence on pore-water pressure and matric suction. A 3D horn-like failure mode is adopted to characterize the collapse of unsaturated backfills. The explicit expression of seismic active earth pressure can be derived by the principle of energy dissipation, where the seismic effect is assembled into the present study as a uniformly distributed inertia force. Comparison results with previously published literature show good agreement. Parametric studies are further performed to investigate the influences of several parameters on the retaining wall. This approach provides a useful tool for reflecting the true response behaviors of critical failure mechanism and evaluating the stability of unsaturated cohesive backfills.

Seismic Active Earth Pressure on Narrow Backfill Retaining Walls Considering Strain Localization

The evaluation of seismic active earth pressure acting on narrow backfilled retaining walls is more essential during earthquake loading to ascertain safety and economical design. This paper proposes an analytical procedure to evaluate seismic active earth pressure for narrow backfill width retaining walls using the limit equilibrium method under earthquake loading. The existence of rock behind the retaining wall that affects the size and shape of the failure wedge in narrow backfill soil is considered. The study also accounts for the strain softening behavior under earthquake loading by considering the change in shear strength due to the reduction in friction angle from peak to residual along the bilinear failure slip surfaces in backfill soil. The formation of multiple failure surfaces due to multiple failure wedges in the narrow backfill soil is also considered. The proposed values of seismic active earth pressure are validated by comparing the obtained results with the earlier studies. The influence of backfill soil friction angle, dilatancy angle, interface friction angle between the retaining wall and backfill soil, interface friction angle between the rock face and backfill soil, backfill slope angle, rock-face slope angle, and the distance of constraint rock face boundary from retaining wall on the magnitude of seismic active earth pressure and its point of application are presented.

Simplified Calculation Method for Seismic Active Earth Pressure of Translational Retaining Wall considering Soil Arching Effect

At present, most seismic earth pressure theories have the limitations of complex derivation process and difficult solution. To solve these problems, considering the deflection of small principal stress caused by soil arching effect, the central arc soil arch was approximated to two inclined linear soil arches, which can greatly simplify the derivation process. Firstly, by improving the combination of differential thin‐layer element method and pseudostatic method, the theoretical formulas of seismic active earth pressure intensity, resultant force size, and resultant force action point under translation mode (T mode) were derived and were verified by experimental results. Then, the influence of soil internal friction angle, wall‐soil friction angle, and seismic coefficient on seismic active earth pressure theory was analyzed. The results show that the seismic active earth pressure is nonlinearly distributed, and the seismic horizontal coefficient has a greater influence than other influence factors. The theoretical results can provide reference for the seismic design of retaining wall.

Probabilistic evaluation of three-dimensional seismic active earth pressures using sparse polynomial chaos expansions

This work presents a probabilistic analysis of three-dimensional (3D) seismic active earth pressures acting on rigid retaining walls that are designed to support cohesive-frictional soil masses. The analysis is implemented using sparse polynomial chaos expansions (SPCE) to represent the physical model responses. The deterministic evaluation of 3D seismic active earth pressures is conducted with the application of the kinematic approach of limit analysis combined with a pseudo-static method. All of the input parameters are deemed as random variables. After the SPCE metamodels are determined, the method of Monte Carle simulations is applied to perform the probabilistic analysis of 3D seismic active earth pressures. The effects of uncertainty levels and correlation relationships of input parameters are investigated. Several illustrative examples of the reliability-based design of retaining walls are shown. Results indicate that uncertainties in input parameters possess a notable effect on 3D seismic active earth pressures, suggesting the need to investigate the problem from a stochastic perspective. In most cases, the soil cohesion, internal friction angle, and seismic coefficient are found to be three of the parameters that affect the final response the most significantly. It is also indicated that considering 3D effects and soil cohesion has a favorable effect on increasing the stability of retained slopes.

Discretization-based kinematical analysis of three-dimensional seismic active earth pressures under nonlinear failure criterion

The available theoretical models for evaluating seismic active earth pressures are limited to plane strain analyses and linear failure criterion. To fill this research gap, with a combination of the kinematical approach of limit analysis, the spatial discretization technique as well as the pseudo-static approach, this work develops a discretized three-dimensional failure mechanism of sloping backfills that is composed of an end cap and a central plane-strain insert to estimate the seismic active earth pressure coefficient under nonlinear failure criterion. Compared with the existing three-dimensional kinematically admissible failure mechanisms, the developed one has three significant merits: (1) the normality condition is strictly satisfied in the generation of the end cap; (2) the work rates can be computed by a summation of elementary work rates conveniently instead of tedious integral schemes; (3) the considerations of the nonlinear failure criterion and the sloping backfill. Comparisons with the existing upper bound solutions and experimental results in terms of active earth forces or active earth pressure coefficients are conducted to verify the proposed model. Parametric studies are performed to study the influences of model parameters, including the seismic coefficient, the sloping angle of backfills as well as the nonlinear parameters, on the active earth pressure coefficients.

Seismic active earth pressure of unsaturated soils with a crack using pseudo-dynamic approach

Abstract The analyses of active earth pressure subjected to earthquake shaking are routinely explored concerning dry or saturated soils. However, the fact often neglected in previous literature is that soils are mostly unsaturated in nature. This work puts forward a kinematical approach for the assessment of active resistance of a rigid retaining structure against unsaturated backfills with pseudo-dynamic approach, and the effect of a crack presented in backfills is also considered. A layer-wise summation method is employed to compute the non-uniformly distributed seismic forces due to earthquake accelerations considering time and spatial effects and corresponding work rates. Several nonlinear formulae as well as different soil-water characteristic curve models are employed to determine the additional cohesion caused by matric suction. To verify the validity of the proposed approach, a comparison is conducted with its simplified modality and conventional pseudo-static approach based on identical input conditions. The comparison results show good agreement. The lateral earth pressure can be derived from the principle of work rate balance using a numerical optimization technique. A parametric analysis is implemented to investigate the influences of crack depth, water level, dynamic factors of seismic effects and nonlinear evaluation models on the critical seismic active earth pressure.

Seismic active earth resistance of submerged backfill considering anisotropic seepage

Based on limit equilibrium analysis, this paper presents a general pseudo-dynamic solution for the seismic active earth pressure considering anisotropic seepage conditions. The proposed method is applied to a vertical waterfront wall retaining fully submerged backfill with a drainage system along the soil-structure interface. To simplify the calculation, a steady state hydraulic head field satisfying Darcy’s law in the backfill and a two-dimensional seepage distribution with anisotropic permeability is assumed. And the anisotropic coefficient is introduced to evaluate the anisotropic seepage differences in the vertical and horizontal directions. Then the analytical derivation includes the pore pressures induced by the anisotropic seepage, the excess pore pressures triggered by earthquake actions and the seismic inertial forces obtained by the pseudo-dynamic method. To reveal the mechanism of seismic active earth pressure, the influences of seismic load characteristics, friction angles, and anisotropic seepage conditions on the total active earth pressure are investigated by parametric studies. The results indicate that the presence of anisotropic seepage leads to a decrease of the seismic active earth pressure. Finally, the calculations of the present solution are compared with the findings of previous research to verify the rationality of the proposed method. This method makes some contributions to improve the calculation for the seismic design of waterfront retaining walls.

A Pseudodynamic Approach of Seismic Active Pressure on Retaining Walls Based on a Curved Rupture Surface

Reasonable determination of the magnitude and distribution of dynamic earth pressure is one of the major challenges in the seismic design of retaining walls. Based on the principles of pseudodynamic method, the present study assumed that the critical rupture surface of backfill soil was a composite curved surface which was in combination with a logarithmic spiral and straight line. The equations for the calculation of seismic total active thrusts on retaining walls were derived using limit equilibrium theory, and earth pressure distribution was obtained by differentiating total active thrusts. The effects of initial phase, amplification factor, and soil friction angle on the distribution of seismic active earth pressure have also been discussed. Compared to pseudostatic and pseudodynamic methods for the determination of planar failure surface forms, the proposed method receives a bit lower value of seismic active earth pressures.

Seismic loading on cantilever retaining walls: Full-scale dynamic analysis

The assessment of realistic seismic loading on cantilever retaining wall requires modeling of actual seismic events to act on an integral cantilever wall. In this sense, an analysis is carried out to simulate eight candidate earthquake time histories. Scaling effect on seismic motions is taken into consideration through a one-dimensional numerical calculation using SHAKE2000 software. Two-dimensional PLAXIS finite element analysis is carried out through a full-scale seismic analysis of a typical cantilever retaining wall. Results of the analysis quantified seismic earth pressure in terms of magnitude and point of application. These results are presented in a non-dimensional chart to be compared with up-to-date seismic loading propositions. In conclusion, a relationship is proposed to relate the horizontal seismic inertial coefficient with a representative lateral seismic active earth pressure coefficient.

Pseudo-dynamic lateral earth pressures on rigid walls with varying cohesive-frictional backfill

This study provides a procedure for assessing the seismic active and passive earth pressure acting on a rigid retaining wall, using the discretization-based kinematic analysis. Such a procedure is capable of considering varying soil properties of the backfill that widely exist in engineering practice owing to the nature of their origins and deposition, which otherwise would be difficult to be considered in conventional upper bound analysis. This is achieved by discretizing the backfill into finite elements by generating a coherent kinematically admissible failure mechanism. The current methodology (modified pseudo-dynamic approach) computes the time- and spatial effects of seismic acceleration through the inclusion of primary and shear waves. External and internal rates of work are calculated through summation of the elementary rates of work. Based on the work rate balance equation, upper bound formulations of active and passive earth pressures (coefficients) are derived in a pseudo-dynamic manner, with the specific kinematic solutions obtained with an optimization procedure. The active (passive) earth pressure coefficient undergoes a decrement (increment) with increasing soil cohesion and friction angle of the backfill, wall adhesion and friction, and shear wave velocity within certain range; and vice versa for the seismic acceleration’s effect.

Stability Assessment of Earth Retaining Structures under Static and Seismic Conditions

An accurate estimation of static and seismic earth pressures is extremely important in geotechnical design. The conventional Coulomb’s approach and Mononobe-Okabe’s approach have been widely used in engineering practice. However, the latter approach provides the linear distribution of seismic earth pressure behind a retaining wall in an approximate way. Therefore, the pseudo-dynamic method can be used to compute the distribution of seismic active earth pressure in a more realistic manner. The effect of wall and soil inertia must be considered for the design of a retaining wall under seismic conditions. The method proposed considers the propagation of shear and primary waves through the backfill soil and the retaining wall due to seismic excitation. The crude estimate of finding the approximate seismic acceleration makes the pseudo-static approach often unreliable to adopt in the stability assessment of retaining walls. The predictions of the active earth pressure using Coulomb theory are not consistent with the laboratory results to the development of arching in the backfill soil. A new method is proposed to compute the active earth pressure acting on the backface of a rigid retaining wall undergoing horizontal translation. The predictions of the proposed method are verified against results of laboratory tests as well as the results from other methods proposed in the past.

Seismic Active Earth Pressure for Soils with Tension Cracks

Seismic Active Earth Pressure for Soils with Tension Cracks

Closed-Form Solution for Seismic Earth Pressure on Bilinear Retaining Wall Using Method of Characteristics

ABSTRACT This paper presents a simplified mathematical formulation for a set of closed-form solutions to compute static and seismic active and passive earth pressure on a retaining wall with bilinear backface. The concept of the method of stress characteristics in the framework of hyperbolic partial differential equations has been employed for the intended purpose. The advantage of varying the wall geometry for obtaining an economical design is briefly discussed. This mathematically robust but elementary procedure may be useful as a predecessor for obtaining an efficient and economical design of a retaining wall to palliate the earthquake damage.

Seismic active earth pressure on rigid retaining walls under rotation about base considering principal-stress rotations by pseudo-static method

Seismic active earth pressure on rigid retaining walls under rotation about base considering principal-stress rotations by pseudo-static method

Influence factors on the seismic behavior and deformation modes of gravity retaining walls

This study investigated the influence factors on the seismic response and deformation modes of retaining walls using large-scale model shaking table tests. Experimental results showed that the distribution of peak seismic earth pressures along the height of a wall was a single peak value curve. The seismic earth pressures on a gravel soil retaining wall were larger than the pressures on the weathered granite and quartz retaining walls. Also, the peak seismic earth pressure increased with increases in the peak ground acceleration and the wall height. The measured seismic active earth pressures on a rock foundation retaining wall were larger than the calculated values, and the action position of resultant seismic pressure was higher than 0.33 H. In the soil foundation retaining wall, the measured seismic earth pressures were much smaller than the calculated values, while the action position was slightly higher than 0.33 H. The soil foundation retaining wall suffered base sliding and overturning under earthquake conditions, while overturning was the main failure mode for the rock foundation retaining walls.

A Study on the Static and Seismic Earth Pressure Problems in Anisotropic Granular Media

The limit load in stability problems in soils is often influenced by the inherent anisotropy. Accordingly, it can be more or less misestimated if an anisotropic soil is simply assumed as being isotropic. In this research, the static and seismic active and passive earth pressures of vertical retaining walls in anisotropic sands are investigated by the use of the lower bound limit analysis method in conjunction with the finite elements and linear programming optimization technique. In this regard, the effect of friction angle anisotropy on the limit pressure was considered. To do so, an iterative procedure was made to incorporate the effect of soil anisotropy. In the proposed iterative procedure, the friction angle was incrementally updated after each iteration. After sufficient iterations, a converged solution and a consistent field of friction angle is achieved which satisfy the convergence criteria of the direction of the major principal stresses and the limit load, as well as a stable stress field. It is worth mentioning that the pseudo-static approach was considered in order to apply the seismic condition. The results were compared with those found in the literature and some design charts were developed. Findings indicate that the passive earth pressure coefficient is much more influenced by the degree of anisotropy than the active earth pressure coefficient.

Effect of Wall Inclination on Dynamic Active Thrust for Cohesive Soil Backfill

Design of retaining walls under seismic conditions is based on the calculation of seismic earth pressurebehind the wall. To calculate the seismic active earth pressure behind the vertical retaining wall, many researchers reportanalytical solutions using the pseudo-static approach for both cohesionless and cohesive soil backfill. Design charts havebeen presented for the calculation of seismic active earth pressure behind vertical retaining walls in the non-dimensionalform. For inclined retaining walls, the analytical solutions for the calculation of seismic active earth pressure as well as thedesign charts (in non-dimensional form) have been reported in few studies for c-ϕ soil backfill. One analytical solution forthe calculation of seismic active earth pressure behind inclined retaining walls by Shukla (2015) is used in the present studyto obtain the design charts in non-dimensional form. Different field parameters related with wall geometry, seismic loadings,tension cracks, soil backfill properties, surcharge and wall friction are used in the present analysis. The present study hasquantified the effect of negative and positive wall inclination as well as the effect of soil cohesion (c), angle of shearingresistance (ϕ), surcharge loading (q) and the horizontal and vertical seismic coefficient (kh and kv) on seismic active earthpressure with the help of design charts for c-ϕ soil backfill. The design charts presented here in non-dimensional form aresimple to use and can be implemented by field engineers for design of inclined retaining walls under seismic conditions. Theactive earth pressure coefficients for cohesionless soil backfill achieved from the present study are validated with studiesreported in the literature.

A finite element performance-based approach to correlate movement of a rigid retaining wall with seismic earth pressure

The paper presents a unique finite element model-based investigation and development of a relationship between the seismic active and passive earth pressure and the movement of a rigid retaining wall. A hardening soil with small strain model with consideration of the Rayleigh damping has been adopted for modelling soil. Validation of the finite element model has been carried out by using centrifuge test results already available in the literature. Unique design charts have been proposed highlighting the relationship between the seismic earth pressure and the wall movement. It is observed that the seismic active earth pressure is independent of the seismic input motion and hence does not depend upon the wall movement during an earthquake, while on the contrary the seismic passive earth pressure is significantly affected by it. Comparison of the results of the present study with the Mononobe-Okabe and pseudo-dynamic methods clearly highlights that the latter overestimates the seismic earth pressure. The proposed design charts and other results provide an important cue to the design engineers.

Effect of Soil Amplification on Seismic Earth Pressure Using Pseudo-Dynamic Approach

The study of seismic earth pressure is essential for the design of a retaining wall in the earthquake-prone regions. Pseudo-static and pseudo-dynamic approaches are widely used for cohesionless soil backfill without considering the effect of soil amplification. Soil amplification is a very important factor for the calculation of seismic active earth pressure and should not be ignored in the design in the earthquake-prone regions. In this paper, a generalized formulation has been presented to compute the seismic active earth pressure distribution on the inclined retaining wall back-face. The retaining wall supports the inclined cohesionless soil backfill. A parametric study has been conducted to study the effect of various parameters like soil friction angle, the inclination of wall back-face, the inclination of soil backfill, wall friction angle, soil amplification, horizontal and vertical seismic coefficients. The results of the present study have been compared with the available results of an earlier study. The study highlighted the effect of model parameters on seismic earth pressure.

Seismic Active Earth Pressure for Inclined Rigid Retaining Walls Considering Rotation of the Principal Stresses with Pseudo-Dynamic Method

AbstractConsidering the effects of the rotation of the principal stresses, time effects, and wall–back inclination, a new solution for the seismic active failure angle is derived by the pseudodynam...