Passive Earth Pressure Coefficients Research Articles

Passive earth pressure against retaining wall using log-spiral arc

Abstract Passive earth pressure against retaining wall depends on a number of factors such as, soil friction angle ϕ, soil wall friction angle δ, backfill angle (ground surface inclination behind wall β, inclination of wall face on horizontal α, and surface of rupture. Several theory have been developed to over come this problem, i. e., determine the coefficient of passive earth pressure using the plane surface of rupture. One of the important parameter which effect on the coefficient of the passive earth pressure surface of rupture. In the present paper , formulation is proposed for calculating coefficient of passive earth pressure on a rigid retaining wall undergoing horizontal translation base on surface of rupture consisting log-spiral and linear segments assisted by computer program (MATLAB program used). The present study is compared with coulomb’s results. The comparison between present study and coulomb’s values shows the present study predict values of earth pressure much less than those of coulomb’s values specially if δ≥ 0.3 ϕ. Those results agree with anthers researches In order facilitate calculation coefficient of passive earth pressure, using the proposed equations, a modified coefficient of passive earth pressure is provided. It is function of (ϕ, δ, β, α).

Seismic Passive Earth Pressure with Seepage for Cohesionless Soil

The authors deal with the computing seismic passive earth pressure acting on a vertical rigid wall. The wall is provided with a drainage system along soil-structure interface and retains the cohesionless backfill subjected to water seepage. A general solution for the seismic passive earth pressure is presented. The solution is based on Coulomb's theory wherein seismic forces are assumed to be pseudostatic. The solution considers the pore water pressures induced by water seepage and earthquake shaking. Some important parameters are included in the solution. The parameters are the soil effective internal friction angle, wall friction, soil unit weight, and horizontal and vertical seismic acceleration coefficients. The comparison of the total seismic passive earth pressure in horizontal direction from the present method with published works indicates that the present method may be reasonable. The variations of the passive earth pressure coefficient with the soil effective internal friction angle are investigated for different wall friction angles and seismic forces. The effect of the water seepage on the seismic passive earth pressure is also investigated.

Numerical study of passive and active earth pressures of sands

The passive and active earth pressures, acting against a vertical retaining wall are often a function of many parameters. In this paper, series of two dimensional finite difference analyses have been carried out with the Fast Lagrangian Analysis of Continua code (FLAC), to estimate the passive and active earth pressure coefficients, for various mechanical and geometrical configurations of backfill retained by a vertical rigid wall. The effect of backfill inclination, soil–wall interface friction angle and proximity of a slope are investigated. The results of the present study are compared with those available in the literature. The analyses show that the distance between the wall and the crest of the slope influence considerably the earth pressures coefficients.

The Research of Earth Pressure behind the Abutment of Integral Abutment Bridge in Uniform Temperature Difference

The earth pressure behind the abutment of integral abutment bridge was measured in practice. The distribution and variation laws of the earth pressure are analyzed in seasonal falling and rising temperature difference through the test data. At the same time, the mathematical model of the coefficient of passive earth pressure when temperature rising under different ratio of the superstructure deformation and the height of abutment is established. Based on the mathematical model, the calculation value of the earth pressure behind the abutment in rising temperature difference is mainly agreement with the measured value

Passive earth-pressure coefficients by upper-bound numerical limit analysis

A three-dimensional (3D) numerical implementation of the limit analysis upper-bound theorem is used to determine passive horizontal earth-pressure coefficients. An extension technique allowing determination of the 3D passive earth pressures for any width-to-height ratios greater than 7 is presented. The horizontal passive earth-pressure coefficients are presented and compared with solutions published previously. Results of the ratio between the 3D and two-dimensional horizontal passive earth-pressure coefficients are shown and found to be almost independent of the soil-to-wall friction ratio. A simple equation is proposed for calculating this passive earth-pressure ratio.

Analysis of Passive Earth Pressure and Displacements of Retaining Walls Using Pseudo-Dynamic Approach

Using additional dynamic parameters in the pseudo-static method like shear wave and primary wave velocities of soil, phase change in the shear and primary waves, and soil amplification for seismic accelerations, one can benefit from another useful tool called pseudo-dynamic method to solve the problem of earth pressures. In this study, the pseudo-dynamic method is used to compute the seismic passive earth pressures on a rigid gravity retaining wall by considering both the planar failure and composite failure (log-spiral and planar) mechanisms. To validate the present formulation, passive earth pressure computed by the present method are compared with those given by other authors. Seismic passive earth pressure coefficients are provided in tabular form for different parameters. The sliding and rotational displacements are also computed and results of the comparative study showed that the assumption of planar failure mechanism for rough soil-wall interfaces significantly overestimates passive earth pressure and underestimate the sliding and rotational displacements.

Limit analysis of cantilever retaining walls with spaced piles

A modified method is proposed for designing cantilever retaining walls with spaced piles. The approach used is based on a new translational three-dimensional failure mechanism within the framework of the upper-bound theorem of limit analysis. Numerical optimisation of the mechanism is performed by a minimisation procedure for the critical three-dimensional passive earth pressure coefficient. Internationally accepted analytical methods for designing these types of retaining structure assume a simplified rectilinear earth pressure distribution, not only for non-spaced piles but also for spaced piles, where the earth pressure distribution is multiplied by the pile spacing. The results of the proposed method indicate that the pile-to-pile spacing, depending on the input soil parameters, strongly influences the shape of the three-dimensional failure mechanism and the passive pressure along the embedment depth to the point of moment equilibrium. Distribution of the passive earth pressure is no longer rectilinear, but the earth mass contributing to the soil–pile interaction on the dredged side of the embedment depth is reduced, which leads to longer piles and higher inner forces in the retaining structure.

Lateral Performance of Full-Scale Bridge Abutment Wall with Granular Backfill

Bridge abutments typically contain a backwall element that is designed to break free of its base support when struck by a bridge deck during an earthquake event and push into the abutment backfill soils. Results are presented for a full-scale cyclic lateral load test of an abutment backwall configured to represent the dimensions ( 1.7 m height), boundary conditions, and backfill materials (compacted silty sand) that are typical of California bridge design practice. An innovative loading system was utilized that operates under displacement control and that assures horizontal wall displacement with minimal vertical displacement. The applied horizontal displacement ranged from null to approximately 11% of the wall height (0.11H) . The maximum earth pressure occurred at a wall displacement of 0.03H and corresponded to a passive earth pressure coefficient of Kp =16.3 . The measured force distribution applied to the wall from hydraulic actuators allowed the soil pressure distribution to be inferred as triangula...

Computation of sliding displacements of bridge abutments by pseudo-dynamic method

The paper focuses on seismic sliding displacement calculations of gravity wall bridge abutments when subjected to passive condition during earthquakes. Pseudo-dynamic approach has been used for the calculation of the passive seismic earth pressure. A novel element of the present investigation is the computation of seismic passive earth pressure coefficients by considering the composite curved rupture surface behind the abutment wall in the framework of limit equilibrium method. Sliding failure along the wall base is considered in the new pseudo-dynamic method. The critical seismic acceleration coefficient for sliding and sliding component of the displacement, resulting from horizontal and vertical sinusoidal ground accelerations, are computed by using Newmark's sliding block method. The effect of sliding on the response of earth structures is evaluated and comparisons are made between sliding displacements calculated using planar and composite failure mechanisms. Results of the comparative study showed that the assumption of planar failure mechanism for rough soil–wall interfaces significantly overestimates the critical seismic accelerations for sliding and underestimates the sliding displacements.

Coulomb-type solutions for passive earth pressure with steady seepage

Present paper deals with the computing of passive earth pressure acting on the vertical rigid retaining wall supporting the soil mass subjected to water seepage. The basic assumptions of Coulomb’s theory and the 2-dimensional steady flow function are used. Three Coulomb-type solutions for the passive earth pressures are presented for the walls provided with three different drainage systems respectively. Based on the general solutions, the variations of the critical inclination of the failure surface and the coefficient of passive earth pressure with increasing the effective friction angle of the soil mass, the soil/structure friction angle, and the water/soil unit weight ratio are discussed. Two tables with values of the coefficients of passive earth pressure for Cases 1 and 3 respectively are also presented.

Seismic passive resistance with vertical seepage and surcharge

Present paper focuses on the computation of the seismic passive earth pressure acting on a vertical rigid retaining wall by a soil mass subjected to vertical steady-state seepage and a uniform surcharge load. Based on the basic assumptions of Coulomb's theory and a pseudo-static method of analysis, a general solution for the passive earth pressure containing two coefficients is presented. In the solution, many parameters, such as unit weight of saturated soil, soil effective internal friction angle, soil/wall friction angle, water/soil unit weight ratio, surcharge intensity coefficient, horizontal and vertical seismic acceleration coefficients, Poisson's ratio of soil mass, hydraulic gradient, and coefficients of pore water pressure, are considered. The effects of hydraulic gradient and seismic forces on passive earth pressure coefficient and passive earth pressure distribution are investigated. The results indicate that passive earth pressure increases with increasing hydraulic gradient for downward water flow case, but decreases for upward water flow case, and that the presence of seismic forces induces a reduction in passive earth pressure.

Numerical evaluation of 3D passive earth pressure coefficients for retaining wall subjected to translation

The 2D passive earth pressures acting on rigid retaining walls problem has been widely treated in the literature using different approaches (limit equilibrium, limit analysis, slip line and numerical computation), however, the 3D passive earth pressures problem has received less attention. This paper is concerned with the numerical study of 3D passive earth pressures induced by the translation of a rigid rough retaining wall for associative soils. Using the explicit finite difference code FLAC 3D (Fast Lagrangian Analyses of Continua), the increase of the passive earth pressures due to the decrease of the wall breadth is investigated. The results given by the present numerical analysis are compared with other investigations using limit equilibrium method, upper-bound method in limit analysis as well as experimental measures. These are presented in a form of design tables relating the geometrical parameters, soil properties, and 3D passive earth pressure coefficients K pγ(3D), K pq(3D) and K pc(3D) representing the effects of soil weight, surcharge loading and soil cohesion, respectively.

Design of a Rigid Cutoff Wall

A sheet pile cutoff wall simply called cutoff wall is used in almost all types of water retaining structures to reduce the exit gradient at the downstream toe and prevent the chances of sand boiling and piping. In 1954, Terzaghi has suggested a simplified approach for the design of cutoff walls considering average seepage force. In Terzaghi’s approach, the unbalanced water pressure around the cutoff wall is coupled with the active earth pressure and the resultant thrust is determined by subtracting the passive thrust from the combined active thrust. The value of passive earth pressure coefficient has been assumed to correspond with a downstream failure wedge having an angle of (45°− ϕ¯ 1 ∕2) with the horizontal, where ϕ¯ 1 =effective angle of internal friction of the foundation soil. In this paper, it is shown that under steady state flow conditions for a flexible levee base, failure does not take place always at this angle. Considering exact seepage forces and applying the laws of equilibrium, active and...

Passive and active earth pressures in the presence of groundwater flow

This paper deals with the effect of seepage flow on the lateral earth pressures acting on deep sheeted excavations in cohesionless soil. The computation of the passive and active earth pressures in the presence of hydraulic gradients is performed using the explicit finite difference method implemented in Fast Lagrangian Analysis of Continua (FLAC) code. The available effective passive earth pressure coefficients in the presence of upward seepage forces are given for both associative and non-associative material. The present solutions show that the soil dilation angle influences the effective passive earth pressures for large internal friction angle values of the soil. They also show that the effective passive pressures diminish with the hydraulic head loss. Good agreement is observed between the present results and those using an upper-bound approach in limit analysis for an associative material. For the active case, the effect of downward seepage forces on the active earth pressures is investigated. The numerical results show a significant increase in the effective active earth pressures due to a hydraulic head loss. It is also shown that the dilation angle influences the effective active earth pressures for large internal friction angle values.

Passive Earth Pressure of Overconsolidated Cohesionless Backfill

An experimental investigation on the passive earth pressure of overconsolidated cohesionless soil on retaining walls was conducted. A prototype model of a vertical rough wall, retaining horizontal backfill, was developed in the laboratory. The model was instrumented to measure the total passive earth pressure acting on the wall, the passive earth pressure acting on selected locations on the wall, and the overconsolidation ratio (OCR) of the sand in the testing tank. In order to develop the state of passive pressure, the wall was pushed horizontally toward the backfill without any rotation. Overconsolidated sand was produced in the testing tank by placing the sand in thin layers; each was compacted mechanically for a period of time. Tests were performed on walls retaining homogeneous overconsolidated sand, and overconsolidated sand backfill overlying the deep sand layer. The method of slices developed for predicting the coefficient of passive earth pressure for normally consolidated soil was adopted for the conditions stated above. The theoretical values compared well with the experimental results of the present investigation. It is of interest to note that the OCR and the soil condition below the founding level significantly affect the value of the coefficient of passive earth pressure on these walls. Design charts and formulae are presented for practical use.

Seismic Passive Earth Pressures in Soils

Seismic passive earth pressure coefficients were computed by the method of limit equilibrium using a pseudostatic approach for seismic forces. Composite curved rupture surfaces were considered in the analysis. While earlier studies using this type of analysis were mainly for sands, seismic passive earth pressure coefficients were obtained in the present study considering the effects of cohesion, surcharge, and own weight. The minimum seismic passive force was obtained by adding the individual minimum values of these components and the validity of the principle of superposition was examined. Other parameters considered in the analysis were wall batter angle, ground surface slope, soil friction angle, wall friction angle, wall adhesion to soil cohesion ratio, and horizontal and vertical seismic accelerations. The seismic earth pressure coefficients were found to be highly sensitive to the seismic acceleration coefficients both in the horizontal and vertical directions. Results of the study are presented in the form of figures and tables. Comparisons of the proposed method with available theories in the seismic case are also presented.

Active and passive earth pressure coefficients by a kinematical approach

Active and passive earth pressure coefficients by a kinematical approach

Discussion: Active and passive earth pressure coefficients by a kinematical approach

Discussion: Active and passive earth pressure coefficients by a kinematical approach

Analytical solution of passive earth pressure

INTRODUCTION It is well recognised that, when wall friction is present, a non-uniform stress field arises as well as a non-planar failure surface. This renders the problem of computing exact values of earth pressures non-trivial, and analytical solutions are not available in this case. In particular, when dealing with passive earth pressure, current practice relies on solutions provided by limit equilibrium methods with a curved (typically log-spiral) surface, but as these procedures are essentially of kinematical nature they are not conservative. In fact, should the assumed mechanism be admissible in kinematics terms, these solutions represent an upper bound of the exact solution. For this reason it is of interest to search for a statically admissible stress field, because this approach provides a conservative answer or the exact one (Calladine, 1985). In this respect, the numerical solution obtained by Sokolowski (1965), based on the method of characteristics, is actually of major interest, and the one most commonly used by designers is that of Caquot & Kerisel (1948) or Kerisel & Absi (1990). This paper is intended to contribute to this problem by providing an analytical solution for earth pressure coefficients, based on the lower bound theorem of plasticity. The expression obtained for the passive earth pressure coefficient is

Seismic passive resistance in soils for negative wall friction

In the presence of pseudo-static seismic forces, passive earth pressure coefficients behind retaining walls were generated using the limit equilibrium method of analysis for the negative wall friction angle case (i.e., the wall moves upwards relative to the backfill) with logarithmic spirals as rupture surfaces. Individual density, surcharge, and cohesion components were computed to obtain the total minimum seismic passive resistance in soils by adding together the individual minimum components. The effect of variation in wall batter angle, ground slope, wall friction angle, soil friction angle, and horizontal and vertical seismic accelerations on seismic passive earth pressures are considered in the analysis. The seismic passive earth pressure coefficients are found to be highly sensitive to the seismic acceleration coefficients both in the horizontal and the vertical directions. The results are presented in graphical and tabular formats.Key words: seismic passive resistance, limit equilibrium, pseudo-static.