scholarly journals Analysis of passive earth pressure modification due to seepage flow effects

2018 ◽  
Vol 55 (5) ◽  
pp. 666-679 ◽  
Author(s):  
Z. Hu ◽  
Z.X. Yang ◽  
S.P. Wilkinson
Keyword(s):  
Limit Equilibrium ◽  
Retaining Wall ◽  
Reaction Force ◽  
Earth Pressure ◽  
Failure Surface ◽  
Friction Angle ◽  
Seepage Flow ◽  
Fourier Series Expansion ◽  
Passive Earth Pressure ◽  
Interface Friction

Using an assumed vertical retaining wall with a drainage system along the soil–structure interface, this paper analyses the effect of anisotropic seepage flow on the development of passive earth pressure. Extremely unfavourable seepage flow inside the backfill, perhaps due to heavy rainfall, will dramatically increase active earth pressure while reducing passive earth pressure, thus increasing the probability of instability of the retaining structure. A trial and error analysis based on limit equilibrium is applied to identify the optimum failure surface. The flow field is computed using Fourier series expansion, and the effective reaction force along the curved failure surface is obtained by solving a modified Kötter equation considering the effect of seepage flow. This approach correlates well with other existing results. For small values of both the internal friction angle and interface friction angle, the failure surface can be appropriately simplified with a planar approximation. A parametric study indicates that the degree of anisotropic seepage flow affects the resulting passive earth pressure. In addition, incremental increases in the effective friction angle and interface friction angle both lead to an increase in passive earth pressure.

scholarly journals Calculation of Active Earth Pressure for Narrow Backfill with a Curved Slip Surface

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Zhihui Wang ◽  
Aixiang Wu ◽  
Yiming Wang
Keyword(s):  
Equilibrium Equation ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Retaining Wall ◽  
Earth Pressure ◽  
Failure Surface ◽  
Friction Angle ◽  
Force Balance ◽  
Vertical Force ◽  
The Earth

A method was proposed to calculate the earth pressure from a cohesionless backfill with a high aspect ratio (ratio of height to width of retaining wall). An exponential equation of slip surface was proposed first. The proposed nonlinear slip surface equation can be obtained once the width and height of the backfill as well as the internal friction angle of the backfill were given. The failure surface from the proposed formula agreed well with the experimental slip surface. Then, the earth pressure was calculated using a simplified equilibrium equation based on the proposed slip surface. It is assumed that the minor principal stress of the backfill near the wall and at its corresponding slip surface where the depth is the same is the same. Thus, based on the vertical force balance of the horizontal backfill strip, assuming the wall-soil interface and the slip surface is in the limit equilibrium state, defined by the Mohr–Coulomb criterion, the differential equilibrium equation was obtained and numerically solved. The calculated results agreed well with the test data from the published literature.

Determination of passive earth pressure coefficients using limit equilibrium approach coupled with the Kötter equation

2015 ◽  
Vol 52 (9) ◽  
pp. 1241-1254 ◽  
Author(s):  
Mrunal A. Patki ◽  
J.N. Mandal ◽  
D.M. Dewaikar
Keyword(s):  
Limit Equilibrium ◽  
Retaining Wall ◽  
Earth Pressure ◽  
Failure Surface ◽  
Passive Earth Pressure ◽  
Pressure Coefficients ◽  
Composite Failure ◽  
Equilibrium Approach ◽  
The Moment

A numerical method is developed to evaluate the passive earth pressure coefficients for an inclined rigid retaining wall resting against a horizontal cohesionless backfill. A composite failure surface comprises a log spiral, and its tangent is assumed in the present study. The unique failure surface is identified based on the limit equilibrium approach coupled with the Kötter equation (published in 1903). Force equilibrium conditions are used to evaluate the magnitude of the passive thrust, whereas the moment equilibrium condition is employed to determine the location of the passive thrust. The distinctive feature of the present study is that no assumption is required to be made regarding the point of application of the passive thrust, which would otherwise be an essential criterion with respect to the several limit equilibrium based investigations available in the literature. The passive earth pressure coefficients, Kpγ, are evaluated for various values of soil frictional angle [Formula: see text], wall frictional angle δ, and wall inclination angle λ, and compared with the existing results.

Limit equilibrium computation of dynamic passive earth pressure

1995 ◽  
Vol 32 (3) ◽  
pp. 481-487 ◽  
Author(s):  
Ernest E. Morrison Jr. ◽  
Robert M. Ebeling
Keyword(s):  
Limit Equilibrium ◽  
Pressure Coefficient ◽  
Earth Pressure ◽  
Failure Surface ◽  
Friction Angle ◽  
Passive Earth Pressure ◽  
Equilibrium Equations ◽  
Cohesionless Soils ◽  
Earth Pressures ◽  
Earth Pressure Coefficient

Few solution techniques exist for the determination of pseudostatic dynamic passive earth pressures for cohesionless soils. The widely accepted Mononobe–Okabe equation can result in the computing of unconservative values if the wall interface friction angle is greater than half the soil internal friction angle. As an alternate solution, equilibrium equations were formulated assuming a log spiral failure surface, and a research computer program was written to calculate the dynamic passive earth pressure coefficient. The primary purpose of this paper is to present a comparison of results obtained using the Mononobe–Okabe equation with those obtained using the log spiral formulation. Key words : pseudostatic, dynamic, passive earth pressure.

Seismic passive earth pressure coefficients for sands

2001 ◽  
Vol 38 (4) ◽  
pp. 876-881 ◽  
Author(s):  
Jyant Kumar
Keyword(s):  
Limit Equilibrium ◽  
Earth Pressure ◽  
Logarithmic Spiral ◽  
Failure Surface ◽  
Passive Earth Pressure ◽  
Pressure Coefficients ◽  
Straight Line ◽  
Earth Pressures ◽  
Planar Failure ◽  
Seismic Forces

By taking the failure surface as a combination of the arc of a logarithmic spiral and a straight line, passive earth pressure coefficients in the presence of horizontal pseudostatic earthquake body forces have been computed for an inclined wall placed against cohesionless backfill material. The presence of seismic forces induces a considerable reduction in the passive earth resistance. The reduction increases with an increase in the magnitude of the earthquake acceleration. The effect becomes more predominant for loose sands. The obtained results compared well with those reported in the literature using curved failure surfaces. However, the results available in the literature on the basis of a planar failure surface are found to predict comparatively higher passive resistance.Key words: earth pressures, earthquakes, limit equilibrium, plasticity, retaining walls, sands.

Upper Bound Limit Analysis of Passive Earth Pressure of Cohesive Backfill on Retaining Wall

2013 ◽  
Vol 353-356 ◽  
pp. 895-900 ◽  
Author(s):  
Xin Rong Liu ◽  
Ming Xi Ou ◽  
Xin Yang
Keyword(s):  
Upper Bound ◽  
Limit Analysis ◽  
Slip Surface ◽  
Retaining Wall ◽  
Earth Pressure ◽  
Friction Angle ◽  
Cohesive Soil ◽  
Passive Earth Pressure ◽  
Simple Method ◽  
Upper Bound Limit Analysis

In view of the shortage of using classical earth pressure theories to calculating passive earth pressure of cohesive soil on retaining wall under complex conditions. Based on the planar slip surface and the back of retaining wall was inclined and rough assumption, the calculation model of passive earth pressure of cohesive backfill under uniformly distrubuted loads was presented, in which the upper bound limit analysis was adopted. Meanwhile it was proven that the prevailing classical Rankine’s earth pressure theory was a special example simlified under the condition of its assumptions. For it’s difficult to determine the angle of slip surface , a relatively simple method for calculating the angle was proposed by example. And the influence of angle of wall back , friction angle of the interface between soil and retaining wall, cohesion force and internal friction angle of backfill soil to planar sliding surface and passive earth pressure were analyzed. Some good calculation results were achieved, these analysis can provide useful reference for the design of retaining wall.

scholarly journals Arching Effect and Displacement on Theoretical Estimation for Lateral Force Acting on Retaining Wall

2021 ◽  
Author(s):  
Jun-feng Jiang ◽  
Qi-hua Zhao ◽  
Shuairun Zhu ◽  
Sheqin Peng ◽  
Yonghong Wu
Keyword(s):  
Limit Equilibrium ◽  
Retaining Wall ◽  
Earth Pressure ◽  
Friction Angle ◽  
Cohesionless Soil ◽  
Active Earth Pressure ◽  
Theoretical Methods ◽  
Arching Effect ◽  
Comparison Results ◽  
Tension Cracks

Abstract A new approach is proposed to evaluate the non-limit active earth pressure in cohesive-frictional based on the horizontal slices method and limit equilibrium method. This approach takes into account the arching effect, displacement, average shear stress of the soil slice, rupture angle and tension cracks. The accuracy of the proposed method is demonstrated by comparing the experimental results and other theoretical methods. The comparison results show that the proposed approach is suitable for calculating the non-limit active earth pressure in cohesive-frictional soil and cohesionless soil. Additionally, the empirical formulations of the mobilized internal friction angle and soil-wall interface friction angle usually used to cohesionless soil are still applied to cohesive-frictional soil through comparison calculated results of other theoretical methods and finite element method. Some valid formulations of the rupture angle and tension cracks were derived considering the cohesion, wall height, and unit weight.

scholarly journals Study on Passive Earth Pressure of Retaining Wall in Transversely Isotropic Soil

2020 ◽  
Vol 143 ◽  
pp. 01020
Author(s):  
Tao Chen ◽  
Chao Chen ◽  
Fengting Guan ◽  
Ruoyang Zhou
Keyword(s):  
Limit Equilibrium ◽  
Retaining Wall ◽  
Transverse Isotropy ◽  
Earth Pressure ◽  
Transversely Isotropic ◽  
Least Square Method ◽  
Least Square ◽  
Passive Earth Pressure ◽  
Principal Stress Direction ◽  
Tensor Theory

Based on the fabric tensor theory and the principle of least square method, the method of block processing in the same model to explore the variation of the passive earth pressure of the transversely isotropic soil was used in the study. At the same time, primary displacement application and multiple displacement application were applied to change the angle between the large principal stress direction of the filling and the normal direction of the deposition surface to obtain the new strength parameters ci and φi of each block after the model was divided and additionally analyzing the variation of the anisotropic passive earth pressure. The study shows: 1.Considering the transverse isotropy of the soil and reaching the limit equilibrium, the passive earth pressure of the soil after multiple displacement application is not only smaller than that after primary displacement application but also closed to the theoretical solution of Coulomb’s earth pressure; 2.When the soil is inclined, the anisotropy is significant when compared with the horizontal direction.

Analytic solutions of rupture angle in coulomb's earth pressure theory

2013 ◽  
Vol 10 (6) ◽  
pp. 573-576
Author(s):  
Zhiguang Guo ◽  
Guoyong Cheng ◽  
Fan Wang
Keyword(s):  
Limit Equilibrium ◽  
Retaining Wall ◽  
Numerical Test ◽  
Engineering Application ◽  
Earth Pressure ◽  
Reference Value ◽  
Failure Surface ◽  
Analytic Solutions ◽  
Foundation Pit ◽  
Simplified Solution

Coulomb's earth pressure theory is widely used in foundation pit supporting structure and retaining wall design, and Rupture angle is one of the key parameters in determining the failure surface location and the foundation pit influence scope. But there is no explicit formula of rupture angle or some wrong in existing formula. This paper, according to the limit equilibrium condition of slide wedge, obtained the analytical expression of Rupture angle which is the most simplified form in the current information. Through the numerical test this simplified solution is consistent with coulomb theory. The conclusion of this paper has some reference value in engineering application of coulomb theory.

Seismic passive resistance in soils for negative wall friction

2002 ◽  
Vol 39 (4) ◽  
pp. 971-981 ◽  
Author(s):  
Deepankar Choudhury ◽  
K S. Subba Rao
Keyword(s):  
Limit Equilibrium ◽  
Earth Pressure ◽  
Friction Angle ◽  
Wall Friction ◽  
Passive Earth Pressure ◽  
Passive Resistance ◽  
Pressure Coefficients ◽  
Logarithmic Spirals ◽  
Seismic Accelerations ◽  
The Individual

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.

scholarly journals Simplified Method for Calculating the Active Earth Pressure on Retaining Walls of Narrow Backfill Width Based on DEM Analysis

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Minghui Yang ◽  
Bo Deng
Keyword(s):  
Urban Areas ◽  
Limit Equilibrium ◽  
Retaining Wall ◽  
Earth Pressure ◽  
Friction Angle ◽  
Retaining Walls ◽  
Cohesionless Soil ◽  
Particle Flow Code ◽  
Active Earth Pressure ◽  
Dem Analysis

Spaces for backfills are often constrained and narrowed when retaining walls must be built close to existing stable walls in urban areas or near rock faces in mountainous areas. The discrete element method (DEM), using Particle Flow Code (PFC-2D) software, was employed to simulate the behavior of cohesionless soil with narrow width behind a rigid retaining wall when the wall translation moved away from the soils. The simulations focused on the failure model of the soil when the movement of the wall reaches the value where active earth pressure occurs, and the shape of the sliding surface was captured. Then, based on the limit equilibrium method with the obtained slip surfaces in PFC-2D, a simplified analytical method is presented to obtain a solution of the active earth pressure acting on rigid retaining with narrow backfill width. The point of application of the active earth pressure is also obtained. The calculated values agree well with those from physical tests in the previous literature. Furthermore, the effects of the width of the backfill, internal friction angle of soil, and wall-soil friction angle on the distribution of active earth pressure are discussed.

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