Coefficients of active earth pressure with seepage effect

2012 ◽  
Vol 49 (6) ◽  
pp. 651-658 ◽  
Author(s):  
Pérsio L.A. Barros ◽  
Petrucio J. Santos
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Retaining Wall ◽  
Drainage System ◽  
Numerical Procedure ◽  
Ground Surface ◽  
Earth Pressure ◽  
Friction Angle ◽  
Active Earth Pressure ◽  
Plane Failure

A calculation method for the active earth pressure on the possibly inclined face of a retaining wall provided with a drainage system along the soil–structure interface is presented. The soil is cohesionless and fully saturated to the ground surface. This situation may arise during heavy rainstorms. To solve the problem, the water seepage through the soil is first analyzed using a numerical procedure based on the boundary element method. Then, the obtained pore-water pressure is used in a Coulomb-type formulation, which supposes a plane failure surface inside the backfill when the wall movement is enough to put the soil mass in the active state. The formulation provides coefficients of active pressure with seepage effect which can be used to evaluate the active earth thrust on walls of any height. A series of charts with values of the coefficients of active earth pressure with seepage calculated for selected values of the soil internal friction angle, the wall–soil friction angle, and the wall face inclination is presented.

Pseudo-Dynamic Active Earth Pressure on Battered Face Retaining Wall Supporting c-Φ Backfill Considering Curvilinear Rupture Surface

2014 ◽  
Vol 5 (1) ◽  
pp. 39-57
Author(s):  
Sima Ghosh ◽  
Arijit Saha
Keyword(s):  
Wave Velocity ◽  
Retaining Wall ◽  
Pressure Coefficient ◽  
Wedge Angle ◽  
Earth Pressure ◽  
Friction Angle ◽  
Active Earth Pressure ◽  
Horizontal Shear ◽  
Rupture Surface ◽  
Wide Range

In the present analysis, using the horizontal slice method and D'Alembert's principle, a methodology is suggested to calculate the pseudo-dynamic active earth pressure on battered face retaining wall supporting cohesive-frictional backfill. Results are presented in tabular form. The analysis provides a curvilinear rupture surface depending on the wall-backfill parameters. Effects of a wide range of variation of parameters like wall inclination angle (a), wall friction angle (d), soil friction angle (F), shear wave velocity (Vs), primary wave velocity (Vp), horizontal and vertical seismic accelerations (kh, kv) along with horizontal shear and vertical loads and non-linear wedge angle on the seismic active earth pressure coefficient have been studied.

Active earth pressure in cohesive soils with an inclined ground surface

2000 ◽  
Vol 37 (1) ◽  
pp. 171-177 ◽  
Author(s):  
Nirmala Gnanapragasam
Keyword(s):  
Analytical Solution ◽  
Ground Surface ◽  
Earth Pressure ◽  
Failure Surface ◽  
Friction Angle ◽  
Active Earth Pressure ◽  
Overburden Pressure ◽  
Retaining Structure ◽  
Lateral Earth Pressure ◽  
Fixed Orientation

An analytical solution is developed to determine the active lateral earth pressure distribution on a retaining structure when it consists of a cohesive backfill (internal friction angle ϕ > 0, cohesion c > 0) with an inclined ground surface. The solution derived encompasses both Bell's equation (for cohesive or cohesionless backfill with a horizontal ground surface) and Rankine's solution (for cohesionless backfill with an inclined ground surface). The orientation of the failure surface is also determined. Results indicate that, unlike the soil-wall scenarios of Bell and Rankine where the failure planes are parallel with a fixed orientation independent of the overburden pressure, for sloping cohesive backfill (ϕ > 0, c > 0) the slope of the failure surface is a function of the overburden pressure and becomes shallower with depth, thus forming a curvilinear failure surface. The solution developed can also be used to check the sustainability of a slope. The analytical solution can be programmed conveniently in a computer.Key words: retaining structure, active earth pressure, cohesive backfill.

Estimation of Active Earth Pressure on Retaining Wall with Translation Mode

2013 ◽  
Vol 639-640 ◽  
pp. 682-687
Author(s):  
Qing Guang Yang ◽  
Jie Liu ◽  
Jie He ◽  
Shan Huang Luo
Keyword(s):  
Retaining Wall ◽  
Earth Pressure ◽  
Friction Angle ◽  
Active Earth Pressure ◽  
Action Point ◽  
Layer Analysis ◽  
Earth Pressures ◽  
Reduction Coefficient ◽  
Point Of Intersection ◽  
Theoretical Results

Considering the movement effect of translation mode，friction angle reduction coefficient and method of bevel-layer analysis,estimation of active earth pressures is deduced for cohesiveless soil retaining wall with translation mode.In order to validate the feasibility of the proposed approach，a model test for active earth pressures was conducted in laboratory;and the proposed method was used to analyze this model. Experimental and theoretical results indicate that the curve of active earth pressure increases firstly and decreases then along the depth of retaining wall with different values of s/sc,and it has a point of intersection with the curve of Coulomb active earth pressure at the depth of 0.6H，where H is the wall height. Further study indicates that the action point position of the active earth pressure is higher than 1/3 times wall height.

scholarly journals Effect of different parameters of heterogeneous dams on safety factor using the neural network. Case study: Marvan dam

2019 ◽  
Vol 32 (02) ◽  
pp. 126-138
Author(s):  
B. Beiranvand ◽  
A. Mohammadzade ◽  
M. Komasi
Keyword(s):  
Neural Network ◽  
Factor Of Safety ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Drainage System ◽  
Friction Angle ◽  
The Body ◽  
The Neural Network ◽  
The Cost

The drainage system is used to guide the flow of water in the earth dams. Construction of drainage in the dam body to collect and direct the drainage formed in the dam body to keep the slope dry and prevent the increase of pore water pressure in the body. One of the main goals of the designers is to find the minimum factor of safety and, consequently, reduce the cost of construction. In this study, the Marvak dam is modeled with the actual characteristics of the materials in the Geostudio software, and with the change in the dimensions of the drain, the material and the slope of the dam body, the minimum Factor of safety of the dam is obtained. In order to predict the minimum Factor of safety, a two-layer neural network has been used. With the training of the neural network based on the data obtained from heterogeneous dams, a minimum Factor of safety has been extracted for optimization of drainage. Finally, it was determined that the internal friction angle of the body material and the slope of the dam have the greatest effect on the dam factor of safety.

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 Active Earth Pressure of Limited C-φ Soil Based on Improved Soil Arching Effect

2020 ◽  
Vol 10 (9) ◽  
pp. 3243
Author(s):  
Meilin Liu ◽  
Xiangsheng Chen ◽  
Zhenzhong Hu ◽  
Shuya Liu
Keyword(s):  
Retaining Wall ◽  
Pressure Coefficient ◽  
Ground Surface ◽  
Side Wall ◽  
Earth Pressure ◽  
Active Earth Pressure ◽  
Soil Arching ◽  
Retaining Structure ◽  
Arching Effect ◽  
Soil Arching Effect

For c-φ soil formation (cohesive soil) of limited width with ground surface overload behind a deep retaining structure, a modified active earth pressure calculation model is established in this study. And three key issues are addressed through improved soil arching effect. First, the soil-wall interaction mechanism is determined by considering the soil arching effect. The slip surface of a limited soil is proved to be a double-fold line passing through the retaining wall toe and intersecting the side wall of the existing underground structure until it reaches the ground surface along the existing side wall. Second, the limited width boundary is explicated. And third, the variation in the active earth pressure from parameters of limited c-φ soil is determined. The lateral active earth pressure coefficient is nonlinear distributed based on the improved soil arching effect of the symmetric catenary curve. Furthermore, the active earth pressure distribution, the tension crack at the top of the retaining wall and the resultant force and its action point were obtained. By comparing with the existing analytical methods, such as the Rankine method, it demonstrates that the model proposed in this study is much closer to the measured and numerical results. Ignoring the influence of soil cohesion and the limited width will exponentially reduce the overall stability of the retaining structure and increase the risk of accidents.

scholarly journals Mechanisms leading to the 2016 giant twin glacier collapses, Aru Range, Tibet

2018 ◽  
Vol 12 (9) ◽  
pp. 2883-2900 ◽  
Author(s):  
Adrien Gilbert ◽  
Silvan Leinss ◽  
Jeffrey Kargel ◽  
Andreas Kääb ◽  
Simon Gascoin ◽  
...  
Keyword(s):  
Pore Water Pressure ◽  
Water Pressure ◽  
Three Dimensional ◽  
Drainage System ◽  
Stress Transfer ◽  
Friction Angle ◽  
Shear Stresses ◽  
Horizontal Distance ◽  
Mountain Glacier ◽  
Caucasus Mountains

Abstract. In north-western Tibet (34.0∘ N, 82.2∘ E) near lake Aru Co, the entire ablation areas of two glaciers (Aru-1 and Aru-2) suddenly collapsed on 17 July and 21 September 2016. The masses transformed into ice avalanches with volumes of 68 and 83×106 m3 and ran out up to 7 km in horizontal distance, killing nine people. The only similar event currently documented is the 130×106 m3 Kolka Glacier rock and ice avalanche of 2002 (Caucasus Mountains). Using climatic reanalysis, remote sensing, and three-dimensional thermo-mechanical modelling, we reconstructed the Aru glaciers' thermal regimes, thicknesses, velocities, basal shear stresses, and ice damage prior to the collapse in detail. Thereby, we highlight the potential of using emergence velocities to constrain basal friction in mountain glacier models. We show that the frictional change leading to the Aru collapses occurred in the temperate areas of the polythermal glaciers and is not related to a rapid thawing of cold-based ice. The two glaciers experienced a similar stress transfer from predominant basal drag towards predominant lateral shearing in the detachment areas and during the 5–6 years before the collapses. A high-friction patch is found under the Aru-2 glacier tongue, but not under the Aru-1 glacier. This difference led to disparate behaviour of both glaciers, making the development of the instability more visible for the Aru-1 glacier through enhanced crevassing and terminus advance over a longer period. In comparison, these signs were observable only over a few days to weeks (crevasses) or were absent (advance) for the Aru-2 glacier. Field investigations reveal that those two glaciers were underlain by soft, highly erodible, and fine-grained sedimentary lithologies. We propose that the specific bedrock lithology played a key role in the two Tibet and the Caucasus Mountains giant glacier collapses documented to date by producing low bed roughness and large amounts of till, rich in clay and silt with a low friction angle. The twin 2016 Aru collapses would thus have been driven by a failing basal substrate linked to increasing pore water pressure in the subglacial drainage system in response to increases in surface melting and rain during the 5–6 years preceding the collapse dates.

Unified Solution of Coulomb’s Active Earth Pressure for Unsaturated Soils without Crack

2012 ◽  
Vol 170-173 ◽  
pp. 755-761 ◽  
Author(s):  
Wen Biao Liang ◽  
Jun Hai Zhao ◽  
Yan Li ◽  
Chang Guang Zhang ◽  
Su Wang
Keyword(s):  
Principal Stress ◽  
Unsaturated Soils ◽  
Retaining Wall ◽  
Research Result ◽  
Earth Pressure ◽  
Friction Angle ◽  
Matric Suction ◽  
Intermediate Principal Stress ◽  
Active Earth Pressure ◽  
Soil Pressure

Based on the unified solution of shear strength in terms of double stress state variables for unsaturated soils, whilst considering the effect of the intermediate principal stress rationally, the unified solution of Coulomb’s active earth pressure for unsaturated soils without cracks is developed. Comparability of the solution is analyzed and influencing characteristic of each factor is obtained. The research result indicates that: the intermediate principal stress and matric suction have obvious impacts on Coulomb’s active earth pressure for unsaturated soils; Coulomb’s active earth pressure has been decreasing until zero with the increase of unified strength theory parameter and matric suction; Coulomb’s active earth pressure increases with the increase of grading angle of retaining wall and slop angle of backfill, but decreases with the increase of matric suction, effective internal friction angle and matric suction angle, while external friction angle has no obvious influence. The proposed unified solution of Coulomb’s active earth pressure enjoys a wider application, and unified solution of Rankine’s active earth pressure is just the special case. The results are of great significance to soil pressure determination such as slope and foundation pit, and to retaining structures design.

Active pressure on gravity walls supporting purely frictional soils

2012 ◽  
Vol 49 (1) ◽  
pp. 78-97 ◽  
Author(s):  
D. Loukidis ◽  
R. Salgado
Keyword(s):  
Critical State ◽  
Soil Mechanics ◽  
Retaining Wall ◽  
Pressure Coefficient ◽  
Earth Pressure ◽  
Friction Angle ◽  
Soil Mass ◽  
Active Earth Pressure ◽  
Foundation Soil ◽  
Surface Plasticity

The active earth pressure used in the design of gravity walls is calculated based on the internal friction angle of the retained soil or backfill. However, the friction angle of a soil changes during the deformation process. For drained loading, the mobilized friction angle varies between the peak and critical-state friction angles, depending on the level of shear strain in the retained soil. Consequently, there is not a single value of friction angle for the retained soil mass, and the active earth pressure coefficient changes as the wall moves away from the backfill and plastic shear strains in the backfill increase. In this paper, the finite element method is used to study the evolution of the active earth pressure behind a gravity retaining wall, as well as the shear patterns developing in the backfill and foundation soil. The analyses relied on use of a two-surface plasticity constitutive model for sands, which is based on critical-state soil mechanics.

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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