Cohesive Slopes Research Articles

STUDY ON THE SURFACE EROSION OF BARE SLOPE WITH COHESIVE SEDIMENT DUE TO AN ARTIFITIAL RAINFALL

The effect of cohesiveness of sediment on the erosion process of bare-slope was investigated in the this study. Experiments were conducted to understand the topographic change in model slope in an experimental flume due to an artificial rainfall. The clay content ratio is a parameter to be changed in this experiment, and it was seen that the main channel formed on the slope grew narrower and deeper as the clay content ratio increases. And vertical erosion on the bed was found to be more dominant than the lateral bank erosion. It was also understood that the erosion process and the geometry of channel network in case of cohesive slope have different characteristics than those of cohesionless slope.

Variational Stability Analysis of Cohesive Slope by Applying Boundary Integral Equation Method

AbstractApplying the concept of minimum potential energy and the variational method proposed in this paper, one can derive the governing equation and transversality conditions for the critical slip surface of a cohesive land slope described by simplified Janbu's model where both horizontal and vertical inter-slice forces are neglected. The governing equation, transversality conditions and boundary conditions were solved by the boundary integral equation method, which is a one dimensional BIEM, so that the critical slip surface and its associated minimal factor of safety can be determined effectively. By comparison of the results gotten from the boundary integral equation method and other numerical methods, it can be concluded, that, for some simplified cases, by using the boundary integral equation method on slope stability analysis of a cohesive land slope, a more reasonable result can be obtained.

Retrofit-reinforcement of cohesive soil slopes using high strength geotextiles with drainage capability

A series of geotechnical centrifuge physical modeling tests were performed to assess the potential use of a new cost-effective mechanically stabilized earth system for retrofitting marginally stable cohesive slopes. The proposed system utilizes the dual functions of reinforcement and drainage by directly inserting high strength non-woven geotextile strips into slopes, with little or no excavation required behind the slope face. The system significantly increases the factor of safety of potentially unstable cohesive slopes, and can be constructed at less expense and more rapidly than conventional mechanically stabilized earth systems.

Probabilistic Slope Stability Analysis by Finite Elements

In this paper we investigate the probability of failure of a cohesive slope using both simple and more advanced probabilistic analysis tools. The influence of local averaging on the probability of failure of a test problem is thoroughly investigated. In the simple approach, classical slope stability analysis techniques are used, and the shear strength is treated as a single random variable. The advanced method, called the random finite-element method (RFEM), uses elastoplasticity combined with random field theory. The RFEM method is shown to offer many advantages over traditional probabilistic slope stability techniques, because it enables slope failure to develop naturally by “seeking out” the most critical mechanism. Of particular importance in this work is the conclusion that simplified probabilistic analysis, in which spatial variability is ignored by assuming perfect correlation, can lead to unconservative estimates of the probability of failure. This contradicts the findings of other investigators who used classical slope stability analysis tools.

Numerical simulation of metal powder die compaction with special consideration of cracking

Powder die compaction is modelled using the finite element method and a phenomenological material model. The Drucker–Prager cap model is modified with the goal to describe the formation of cracks during powder transfer, compaction, unloading, and ejection of the parts from the die. This is achieved by considering the cohesive strength and the cohesion slope, which characterise the current strength of the powder compact in the Drucker–Prager model, as state dependent variables. Evolution equations are formulated for these variables, so that the strength increases by densification and decreases by forced shear deformation. Some of the parameters appearing in the evolution equations are determined from measured green strength values. An iron based powder (Distaloy AE) is used for the experiments. Examples are shown to demonstrate that the density distribution can be calculated accurately as compared with an experiment, that cracking can be modelled at least qualitatively correctly, and that the compaction of complex 3D parts can be simulated.

Limit analysis of cohesive slopes reinforced with geotextiles : Sawicki, A; Lesniewska, D Comput GeotechV7, N1/2, 1989, P53–66

Limit analysis of cohesive slopes reinforced with geotextiles : Sawicki, A; Lesniewska, D Comput GeotechV7, N1/2, 1989, P53–66

Three-dimensional stability analysis of cohesive slopes : Ugai, K; Nagase, H; Enokido, M Proc Eighth Asian Regional Conference on Soil Mechanics and Foundation Engineering, Kyoto, 20–24 July 1987V1, P509–512. Publ Japan: Japanese Society for Soil Mechanics and Foundation Engineering, 1987

Three-dimensional stability analysis of cohesive slopes : Ugai, K; Nagase, H; Enokido, M Proc Eighth Asian Regional Conference on Soil Mechanics and Foundation Engineering, Kyoto, 20–24 July 1987V1, P509–512. Publ Japan: Japanese Society for Soil Mechanics and Foundation Engineering, 1987

Limit analysis of cohesive slopes reinforced with geotextiles

A method of plastic limit analysis of cohesive slopes reinforced with geotextiles is presented. First, the theoretical model of reinforced cohesive soil is presented, then the formulation of boundary value problems by a method of characteristics described. The bearing capacity of reinforced slopes and the failure surfaces are obtained as the solution to the system of governing equations. The method proposed allows for studying the influence of design parameters, like the unit weight of the soil, the angle of internal friction, cohesion, and the amount of reinforcement, on the stability of reinforced soil structures.

THREE-DIMENSIONAL STABILITY ANALYSIS OF COHESIVE SLOPES WITH CONSIDERATION OF BASE FAILURE

THREE-DIMENSIONAL STABILITY ANALYSIS OF COHESIVE SLOPES WITH CONSIDERATION OF BASE FAILURE

Three dimensional stability analysis of vertical cohesive slopes : Ugai, K Soils FoundV25, N4, Dec 1985, P41–48

Three dimensional stability analysis of vertical cohesive slopes : Ugai, K Soils FoundV25, N4, Dec 1985, P41–48

粘土斜面の安定性に及ぼす端部効果

This paper discusses stability analysis of cohesive slopes with finite length. The method of analysis is based on limit equilibrium techniques and variational calculus. The three-dimensional stability factors are calculated as the functions of the ratio of failure length to slope height and slope angle. Based on these calculations three-dimensional stability charts are presented. And a method of inverse calculation of cohesion c on a three-dimensional slip surface is proposed.

THREE-DIMENSIONAL STABILITY ANALYSIS OF COHESIVE SLOPES

This paper discusses stability analysis of inclined and inhomogeneous cohesive slopes with finite length. The method of analysis is based on three-dimensional limit equilibrium techniques and variational calculus. The three-dimensional stability factors were calculated as the functions of the ratio of failure length (perpendicular to cross section) to slope height, slope angle and factor of inhomogeneity. Based on these calculations the three-dimensional stability charts were presented. The solutions obtained here give the upper bounds of the problem in limit analysis.

Three-Dimensional Stability Analysis of Vertical Cohesive Slopes

ABSTRACT This paper presents a stability analysis of vertical cohesive slopes with a finite length (perpendicular to cross sections of slopes). The method of analysis is based on three-dimensional limit equilibrium techniques and variational calculus. The shapes of three-dimensional critical failure surfaces were determined exactly and found to be split cylinders with curved end caps. Then the three-dimensional factors of safety were calculated as the functions of the ratio of failure length to vertical slope height. These factors of safety were higher than the two-dimensional factors as indicated by Baligh and Azzouz (1975), etc. The method of analysis of this study could be extended to any inclined cohesive slope. The solutions obtained here give the least upper bound of the problem in limit analysis. In practice they can be applied to evaluate the end effects of vertical cuts or excavations in clays in narrow areas.

Loaded areas on cohesive slopes, technical note : Azzouz, A S; Baligh, M M J Geotech Engng Div ASCE, V109, NGT5, May 1983, P724–729

Loaded areas on cohesive slopes, technical note : Azzouz, A S; Baligh, M M J Geotech Engng Div ASCE, V109, NGT5, May 1983, P724–729

Loaded Areas on Cohesive Slopes

Design charts for performing total stress stability analyses of cohesive slopes subjected to strip loads and square loaded areas are developed. The charts for strip-load provide solutions for different load widths and thus are expected to complement existing solutions. Results show that for square loaded areas, end effects can have an important effect on the magnitude of the critical load causing failure. These effects are especially important when the factor of safety of the slope due to its weight only is close to unity. For many practical situations, three-dimensional effects would increase the plane strain critical load by a factor of 5 to 10.

Closure to “End Effects on Stability of Cohesive Slopes”

Closure to “End Effects on Stability of Cohesive Slopes”

Discussion of “End Effects on Stability of Cohesive Slopes”

Discussion of “End Effects on Stability of Cohesive Slopes”

End effects on stability of cohesive slopes : BALIGH, MM MASS. INST. TECH., CAMBRIDGE, USA AZZOUZ, AS MASS. INST. TECH., CAMBRIDGE, USA 8F, 16R J. GEOTECH. ENGNG DIV., ASCE. V101, GT11, NOV. 1975, P1105–1117

End effects on stability of cohesive slopes : BALIGH, MM MASS. INST. TECH., CAMBRIDGE, USA AZZOUZ, AS MASS. INST. TECH., CAMBRIDGE, USA 8F, 16R J. GEOTECH. ENGNG DIV., ASCE. V101, GT11, NOV. 1975, P1105–1117

End Effects on Stability of Cohesive Slopes

The concept of the two-dimensional circular arc method of stability analysis is extended to three-dimensional slope stability problems. End effects on the stability of cohesive slopes due to failure along a finite length are evaluated by means of a computer program STAB3D developed for this purpose. As an application of the technique, two cases are considered: (1) The toe failure of a vertical cut where typical end effects are illustrated; and (2) the toe failure of a slope with any angle β when a finite length of failure is imposed. The stability of a test section embankment loaded to failure is analyzed.

Earthquake resistant design of cohesive earth slopes

As many major slope failures have occurred during medium and strong earthquakes, the assessment of the seismic stability of slopes in earthquake-prone areas is of great concern to engineers. Prior to 1964, little attention was given to the development of rational aseismic design methods for earth slopes. Most design methods were based on a static analysis used in conjunction with an arbitrarily selected lateral force acting on the slope with soil strengths determined by conventional laboratory tests. However, the catastrophic slope failures which occurred during the Alaskan earthquake of 1964, resulted in a considerable reappraisal of such static design methods. In recent years significant progress has been made in developing new methods of laboratory testing to determine dynamic soil properties, improved techniques of analysing the dynamic response of slopes and embankments to earthquakes, and new concepts of aseismic design methods for earth slopes. Although research has yet to provide all the answers, the current state of knowledge at least provides an improved guide to engineering judgement in the assessment of the stability of earth slopes during earthquakes.