Earth pressures on unyielding retaining walls of narrow backfill width

2001 ◽  
Vol 38 (6) ◽  
pp. 1220-1230 ◽  
Author(s):  
W A Take ◽  
A J Valsangkar
Keyword(s):  
Earth Pressure ◽  
Friction Angle ◽  
Retaining Walls ◽  
Centrifuge Modelling ◽  
Reasonable Estimate ◽  
Interface Friction ◽  
Centrifuge Tests ◽  
Earth Pressures ◽  
Nonlinear Calibration ◽  
Good Agreement

Arching theory predicts a significant reduction in earth pressures behind retaining walls of narrow backfill width. An extensive series of centrifuge tests has been performed to evaluate the use of flexible subminiature pressure cells in the centrifuge environment and their subsequent use to measure lateral earth pressures behind retaining walls of narrow backfill width. Although the flexible earth pressure cells exhibit hysteresis and nonlinear calibration behaviour, the extensive calibration studies indicate that stiff diaphragm type earth pressure cells may be used with replicate models to measure earth pressures. Measurements of lateral pressures acting on the unyielding model retaining walls show good agreement with Janssen's arching theory. Tests on backfills bounded by vertical planes of dissimilar frictional characteristics indicate arching theory with an average interface friction angle provides a reasonable estimate of lateral earth pressures.Key words: fascia retaining walls, silos, earth pressures, pressure cells, centrifuge modelling.

scholarly journals Impact of wall movements on the location of passive Earth thrust

2021 ◽  
Vol 13 (1) ◽  
pp. 570-581
Author(s):  
Meriem F. Bouali ◽  
Mahdi O. Karkush ◽  
Mounir Bouassida
Keyword(s):  
Retaining Wall ◽  
Earth Pressure ◽  
Friction Angle ◽  
Retaining Walls ◽  
General Assumption ◽  
Wall Friction ◽  
Wall Movement ◽  
Numerical Predictions ◽  
Test Models ◽  
Earth Pressures

Abstract The general assumption of linear variation of earth pressures with depth on retaining structures is still controversial; investigations are yet required to determine those distributions of the passive earth pressure (PEP) accurately and deduce the corresponding centroid location. In particular, for rigid retaining walls, the calculation of PEP is strongly dependent on the type of wall movement. This paper presents a numerical analysis for studying the influence of wall movement on the PEP distribution on a rigid retaining wall and the passive earth thrust location. The numerical predictions are remarkably similar to existing experimental works as recorded on scaled test models and full-scale retaining walls. It is observed that the PEP varies linearly with depth for the horizontal translation, but it is nonlinear when the movement is rotational about the top of the retaining wall. When rotation is around the top of the wall, the resultant of PEP is located at a depth that varies between 0.164 and 0.259H of the wall height measured from the base of the wall, which is lesser than 1/3 of the wall height. The passive earth thrust location is highly affected by the soil–wall friction angle, especially when the friction angle of the backfill material increases. Despite the herein presented results, further experiments are recommended to assess the corresponding numerical predictions.

Centrifuge testing and numerical analysis of box culverts installed in induced trenches

2010 ◽  
Vol 47 (2) ◽  
pp. 147-163 ◽  
Author(s):  
Benjamin L. McGuigan ◽  
Arun J. Valsangkar
Keyword(s):  
Soil Structure ◽  
Earth Pressure ◽  
Centrifuge Testing ◽  
Centrifuge Tests ◽  
Earth Pressures ◽  
Box Culverts ◽  
Box Culvert ◽  
Contact Pressures ◽  
Base Contact ◽  
Good Agreement

Induced trench construction is routinely used for circular conduits, but its application for box culverts is less common. To understand the complex soil–structure interaction issues related to the design of induced trench box culverts, centrifuge tests were performed to measure earth pressures on a model box culvert installed in several induced trench configurations. These tests were modelled with FLAC and good agreement was achieved. A parametric study performed with FLAC identified a preferred compressible zone geometry having a width of 1.2 times the culvert width and a thickness of 0.5 times the culvert height. For this geometry, the earth pressure on the top was 0.28 times the overburden, the lateral earth pressure on the sides was 0.47 times the mid-height overburden, and the contact pressure at the base was 0.73 times the overburden plus the pressure from the dead load of the culvert. The average base contact pressures for the induced trench geometry were 35% lower than those for the corresponding positive projecting case. The induced trench method, therefore, appears to be a viable option for box culverts installed under high embankments.

Relationship between installation torque and uplift capacity of deep helical piles in sand

2010 ◽  
Vol 47 (6) ◽  
pp. 635-647 ◽  
Author(s):  
Cristina de Hollanda Cavalcanti Tsuha ◽  
Nelson Aoki
Keyword(s):  
Laboratory Tests ◽  
Friction Angle ◽  
Correlation Factor ◽  
Experimental Program ◽  
Uplift Capacity ◽  
Suggested Approach ◽  
Interface Friction ◽  
Helical Piles ◽  
Shear Interface ◽  
Good Agreement

The empirical torque correlation factor (KT), which relates the uplift capacity to the installation torque of helical piles, is routinely used as an on-site instrument for quality control with this type of foundation. This paper presents a theoretical relationship between uplift capacity and installation torque of deep helical piles in sand. An experimental program, including centrifuge and direct shear interface tests, was carried out to validate this expression. The experimental results were compared with the values predicted by the suggested approach and showed good agreement. As the developed model depends on the residual interface friction angle (δr) between the helix surface and the surrounding sand, results of δr, extracted from different sand samples, are presented for use in this suggested relationship on site. Also, the values of KT found in this work were compared with those of field and laboratory tests on helical piles in sand reported in the literature. From this analysis, it was found that the measured values of KT decrease with an increase in pile dimensions and, in most of cases, with an increase in sand friction angle. These results were explained by the presented model.

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 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.

Earth Pressure Analysis and Retaining Walls

2015 ◽  
pp. 313-410
Keyword(s):  
Retaining Wall ◽  
Earth Pressure ◽  
Retaining Walls ◽  
Wall Friction ◽  
Underground Structures ◽  
Retaining Structure ◽  
Earth Pressures ◽  
Braced Excavations ◽  
Surcharge Load ◽  
Line Loads

Retaining walls are structures used not only to retain earth but also water and other materials such as coal, ore, etc. where conditions do not permit the mass to assume its natural slope. In this chapter, after considering the types of retaining wall, earth pressure theories are developed in estimating the lateral pressure exerted by the soil on a retaining structure for at-rest, active, and passive cases. The effect of sloping backfill, wall friction, surcharge load, point loads, line loads, and strip loads are analyzed. Karl Culmann's graphical method can be used for determining both active and passive earth pressures. The analysis of braced excavations, sheet piles, and anchored sheet pile walls are considered and practical considerations in the design of retaining walls are treated. They include saturated backfill, wall friction, stability both external and internal, bearing capacity, and proportioning the dimensions of the retaining wall. Finally, a brief treatment of earth pressure on underground structures is included.

Research and Analysis of Active Earth Pressure on Retaining Walls with Layered Non-Cohesive Backfills

2013 ◽  
Vol 275-277 ◽  
pp. 269-272 ◽  
Author(s):  
Xi Yan Jiang ◽  
Zhan Xue Zhou
Keyword(s):  
Earth Pressure ◽  
Retaining Walls ◽  
Active Earth Pressure ◽  
Layer Analysis ◽  
Earth Pressures ◽  
Set Up

Based on the method of level-layer analysis , with the sliding harmonious condition of layered backfills considered , the theoretical answers to the unit earth pressures , the resultant earth pressures and the points of application of the resultant earth pressures on retaining walls with layered non-cohesive backfills are set up . The comparisons are made with Coulomb’s formula.

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.

Evaluation of active earth pressure by the generalized method of slices

1998 ◽  
Vol 35 (4) ◽  
pp. 591-599 ◽  
Author(s):  
Zuyu Chen ◽  
Songmei Li
Keyword(s):  
Stability Analysis ◽  
Slope Stability ◽  
Slip Surface ◽  
Limit Equilibrium ◽  
Earth Pressure ◽  
Retaining Walls ◽  
Slope Stability Analysis ◽  
Pressure Limit ◽  
The Earth ◽  
Earth Pressures

The generalized method of slices, commonly used in slope stability analysis, can be extended to determine active earth pressures applied to various types of supports. The governing force and moment equlibrium equations are given. In a similar manner to slope stability analysis, the methods of optimization are used to define the critical slip surface that is associated with the maximum wall pressure. Examples show that the approaches give active earth pressures identical to the Rankine solution for gravity walls. For other types of support, such as anchored or strutted walls, the earth pressure is determined by assigning appropriate locations of the point of application on the wall. It has been found that applying the restrictions of physical admissibility is more vital in earth pressure problems than in slope stability assessments.Key words: earth pressure, limit equilibrium method, the method of slices, retaining walls.

scholarly journals Centrifuge modelling of an instrumented free-fall sphere for measurement of undrained strength in fine-grained soils

2016 ◽  
Vol 53 (6) ◽  
pp. 918-929 ◽  
Author(s):  
J.P. Morton ◽  
C.D. O’Loughlin ◽  
D.J. White
Keyword(s):  
Free Fall ◽  
Penetration Resistance ◽  
Centrifuge Modelling ◽  
Fine Grained ◽  
Model Free ◽  
Centrifuge Tests ◽  
Acceleration Data ◽  
Undrained Strength ◽  
Natural Clays ◽  
Good Agreement

This paper describes centrifuge tests in which a model free-fall sphere was allowed to free fall in water before dynamically embedding within reconstituted samples of kaolin clay and two offshore natural clays. Instrumentation within the sphere measured accelerations along three orthogonal axes. The resultant acceleration was used to calculate sphere velocities and displacements. This allowed the penetration resistance acting on the sphere to be expressed in terms of a single capacity factor that captures soil resistance from both shearing and drag, and varies uniquely with the non-Newtonian Reynolds number. Undrained shear strength profiles obtained from a simple inverse analysis of the acceleration data show good agreement with those obtained using conventional push-in penetrometer tests.

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