Effect of the number of coplanar rock bridges on the shear strength and stability of slopes with the same discontinuity persistence

2021 ◽  
Author(s):  
Peng Tang ◽  
Guo-Qing Chen ◽  
Run-Qiu Huang ◽  
Dong Wang
Keyword(s):  
Shear Strength ◽  
Rock Bridges ◽  
Stability Of Slopes

scholarly journals Strength Theory Model of Unsaturated Soils with Suction Stress Concept

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Pan Chen ◽  
Changfu Wei ◽  
Jie Liu ◽  
Tiantian Ma
Keyword(s):  
Shear Strength ◽  
Unsaturated Soils ◽  
Theory Model ◽  
Strength Analysis ◽  
New Model ◽  
Suction Stress ◽  
Strength Change ◽  
Stability Of Slopes ◽  
Moisture State ◽  
The Stability

A theoretical model is developed for describing the strength property of unsaturated soils. The model is able to predict conveniently the strength changes of unsaturated soils undergoing repeated changes of water content. Suction stress is adopted in the new model in order to get the sound form of effective stress for unsaturated soils. The shear strength of unsaturated soils is dependent on its soil-moisture state based on the results of shear experiments. Hence, the parameters of this model are related tightly to hydraulic properties of unsaturated soils and the strength parameters of saturated soils. The predictive curves by the new model are coincident with experimental data that underwent single drying and drying/wetting cycle paths. Hence, hysteretic effect in the strength analysis is necessary to be considered to predict the change of shear strength of unsaturated soils that underwent drying/wetting cycles. Once the new model is used to predict the change of shear strength, lots of time could be saved due to avoiding heavy and complicated strength tests of unsaturated soils. Especially, the model can be suitable to evaluate the shear strength change of unsaturated soils and the stability of slopes experienced the drying/wetting cycles.

A Study of Fracture Mechanism and Shear Strength of Rock Bridges through Analytical and Model-Testing Methods

2004 ◽  
Vol 261-263 ◽  
pp. 225-230 ◽  
Author(s):  
Wei Shen Zhu ◽  
Shu Cai Li ◽  
R.H.C. Wong ◽  
K.T. Chau ◽  
Jian Xu
Keyword(s):  
Shear Strength ◽  
Fracture Mechanism ◽  
Model Testing ◽  
Testing Methods ◽  
Rock Bridges

scholarly journals Parametric evaluation of shear strength parameters on the stability of cut slope: a case study from Mahabaleshwar road section, India

2016 ◽  
Vol 51 ◽  
pp. 73-76
Author(s):  
Suman Panthee
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Shear Strength ◽  
Internal Friction ◽  
Factor Of Safety ◽  
Slope Failure ◽  
Cut Slope ◽  
Stability Of Slopes ◽  
Proportional Relation ◽  
The Stability

Stability of rock cut slopes depends upon the type of material, discontinuity attributes and geometry present in any location. Although, gravity remains the constant important factor in dictating the slope failure but other parameters like shear strength and available shear stress along the slope also decides the stability of the slopes to great extent. The strength of the material comes from the internal bonding between the mineral grains, contact between the particles and the ability of the material to respond to the stress conditions. Variation of these material attributes fluctuate the cohesion and angle of internal friction that constitutes the most important properties in defining the strength of any material. Rock resists shear stress by these two internal mechanisms. Numerical simulation by Finite Element Method technique is attempted for assessing the stability cut slope. An attempt has been made in this study to document the behavior of strength of the material in terms of stability of slopes by parametric study of cohesion and internal friction. This study carried to understand how the factor of safety changes with reference to change in cut slope height, cohesion and internal friction of the discontinuities that attributes the shear strength of discontinuities. The study is based on Finite Element Modeling (FEM). From the study it is found that factor of safety has strongly proportional relation with cohesion and internal friction but shown inversely proportional relation with height of cut slope.

Strength of tree roots and landslides on Prince of Wales Island, Alaska

1979 ◽  
Vol 16 (1) ◽  
pp. 19-33 ◽  
Author(s):  
Tien H. Wu ◽  
William P. McKinnell III ◽  
Douglas N. Swanston
Keyword(s):  
Shear Strength ◽  
Root System ◽  
Forest Cover ◽  
Safety Factors ◽  
In Situ Tests ◽  
Tree Roots ◽  
Stability Of Slopes ◽  
Before And After ◽  
The Stability

The stability of slopes before and after removal of forest cover was investigated. Porewater pressures and shear strengths were measured and the soil properties were determined by laboratory and in situ tests. A model of the soil–root system was developed to evaluate the contribution of tree roots to shear strength. The computed safety factors are in general agreement with observed behaviors of the slopes. Decay of tree roots subsequent to logging was found to cause a reduction in the shear strength of the soil–root system.

Bearing capacity under cyclic loading — offshore, along the coast, and on land. The 21st Bjerrum Lecture presented in Oslo, 23 November 2007This paper represents the written version of the 21st Bjerrum Lecture. While it has been edited for the present publication, it retains the general structure of the original lecture, which was intended for a general geotechnical audience. The Bjerrum Lecture is presented in Oslo in alternate years by the Norwegian Geotechnical Society with the support of the Bjerrum Memorial Fund (Laurits Bjerrums Minnefond).

2009 ◽  
Vol 46 (5) ◽  
pp. 513-535 ◽  
Author(s):  
Knut H. Andersen
Keyword(s):  
Shear Strength ◽  
Cyclic Loading ◽  
General Structure ◽  
Stress Path ◽  
Shear Stresses ◽  
Foundation Design ◽  
Cyclic Shear ◽  
Stability Of Slopes ◽  
Practical Design ◽  
The Stability

Cyclic loading can be important for the foundation design of structures, both offshore, along the coast, and on land, and for the stability of slopes. This is illustrated by several examples. The paper discusses how soil behaves under cyclic loading, both for structures and for slopes, and shows that the cyclic shear strength and the failure mode under cyclic loading depend strongly on the stress path and the combination of average and cyclic shear stresses. Diagrams with the cyclic shear strength of clay, sand, and silt that can be used in practical design are presented. Comparisons between calculations and model tests indicate that foundation capacity under cyclic loading can be determined on the basis of cyclic shear strength determined in laboratory tests.

scholarly journals Experimental Study on Shear Mechanism of Rock-Like Material Containing a Single Non-Persistent Rough Joint

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 987
Author(s):  
Sayedalireza Fereshtenejad ◽  
Jineon Kim ◽  
Jae-Joon Song
Keyword(s):  
Shear Strength ◽  
Normal Stress ◽  
Normal Load ◽  
Shear Behavior ◽  
Image Correlation ◽  
Joint Friction ◽  
Rock Bridges ◽  
Shear Mechanism ◽  
Comprehensive Knowledge ◽  
Before And After

The geometrical and mechanical properties of non-persistent joints as well as the mechanical behavior of intact rock (rock bridges) are significantly effective in the shear strength of weakness planes containing non-persistent joints. Therefore, comprehensive knowledge of the shear mechanism of both joints and rock bridges is required to assess the shear strength of the planes. In this study, the shear behavior of specimens containing a single non-persistent rough joint is investigated. A novel procedure was used to prepare cast specimens embedding a non-persistent (disc-shaped) rough joint using 3D printing and casting technology, and the shear strength of the specimens was examined through an extensive direct shear testing program under constant normal load (CNL) condition. Three levels for three different variables of the joint roughness, rock bridge ratio, and normal stress were considered, and the effects of these factors on the shear behavior of prepared samples were tested. The experimental results show a clear influence of the three variables on the shear strength of the specimens. The results show that the normal stress applied to the jointed zone of weakness planes is considerable, and thus joint friction contribution should be taken into account during shear strength evaluation. Furthermore, the dilation mechanism of the specimens before and after failure was investigated through a digital image correlation analysis. Finally, a camcorder was used to analyze the location and sequence of the initiated cracks.

scholarly journals The mechanics of landslides in Leda clay

1970 ◽  
Vol 7 (3) ◽  
pp. 285-296 ◽  
Author(s):  
W. J. Eden ◽  
R. J. Mitchell
Keyword(s):  
Shear Strength ◽  
Field Observations ◽  
Normal Stresses ◽  
Stress Range ◽  
Stability Of Slopes ◽  
Shearing Resistance ◽  
Mode Of Failure ◽  
Leda Clay ◽  
The Stability ◽  
Drained Shear Strength

An appraisal of the drained shear strength of Leda clay under low effective normal stresses has resulted in a new appreciation of its behavior in this stress range which can be applied to consideration of the stability of slopes. Closely spaced planes of weakness existing in the apparently intact clay give rise to dilatant behavior and predominantly frictional shearing resistance. This mode of failure is consistent with field observations that have been compiled from numerous landslides; three of these landslides are analyzed in this paper.

Framework to assess pseudo-static approach for seismic stability of clayey slopes

2018 ◽  
Vol 55 (12) ◽  
pp. 1860-1876 ◽  
Author(s):  
Mourad Karray ◽  
Mahmoud N. Hussien ◽  
Marie-Christine Delisle ◽  
Catherine Ledoux
Keyword(s):  
Shear Strength ◽  
Numerical Methods ◽  
Failure Surface ◽  
Static Stability ◽  
Static Method ◽  
Dynamic Responses ◽  
Seismic Stability ◽  
Safety Factors ◽  
Stability Of Slopes ◽  
Static Approach

Approaches commonly used to assess the seismic stability of slopes range from the relatively simple pseudo-static method to more complicated nonlinear numerical methods, e.g., finite element (FE) and finite difference (FD). The pseudo-static method, in particular, is widely used in practice as it is inexpensive and substantially less time consuming compared to the much more rigorous numerical methods. However, the pseudo-static method is widely criticized because it does not take into account the effects of the earthquake on the shear strength of the slope material nor the seismic response of the slope. Hence, some researchers recommend its use only in slopes composed of cohesive materials that do not develop significant pore pressures or that lose less than about 15% of their peak shear strength during earthquake shaking. However, the use of the pseudo-static method in these soils is also problematic as clayey slopes generally fail in pseudo-static stability analyses (i.e., factors of safety are less than 1) and the failure surface is completely predominated by the thickness of the clayey layer in the slope or foundation. The reliability of the pseudo-static method in natural clayey slopes is examined here based on rigorous numerical simulations with FLAC. The numerical results are compared and verified using available static and dynamic 1g laboratory tests. This article then addresses some of the crude assumptions of the pseudo-static method and provides practical suggestions to be applied to refine the outcomes of pseudo-static analyses not only in terms of the computed safety factors, but also in the prediction of the failure surface through the consideration of additional aspects of the dynamic responses of the clayey slopes.

Holding Power of Orthopaedic Screws in Metacarpal and Metatarsal Bones of Young Calves

1992 ◽  
Vol 05 (03) ◽  
pp. 100-103 ◽  
Author(s):  
G. Jean ◽  
J. K. Roush ◽  
R. M. DeBowes ◽  
E. M. Gaughan ◽  
J. Kirpensteijn
Keyword(s):  
Shear Strength ◽  
Tensile Load ◽  
Young Female ◽  
Limiting Factor ◽  
Holding Power ◽  
Metatarsal Bones ◽  
Bone Width ◽  
Load To Failure ◽  
Holstein Calves

SummaryThe holding power and holding power per mm bone width of 4.5 mm and 5.5 mm cortical and 6.5 mm cancellous orthopaedic screws were obtained by tensile load-to-failure studies in excised metacarpal and metatarsal bones of young female Holstein calves. Holding power and holding power per mm bone width of 6.5 mm orthopaedic screws were significantly greater than those of 4.5 and 5.5 mm orthopaedic screws in the diaphysis and metaphysis. Significant differences were not detected between holding power and holding power per mm bone width of 4.5 and 5.5 mm orthopaedic screws. The holding power was not different between metacarpi and metatarsi. The limiting factor in all tests of holding power was the shear strength of the bone. We found that 6.5 mm orthopaedic screws have the greatest holding power in the metacarpal and metatarsal bones of young calves.This study compares the holding power of 4.5 mm and 5.5 mm cortical and 6.5 mm cancellous orthopaedic screws in excised metacarpal and metatarsal bones from young female Holstein calves. We found that 6.5 mm orthopaedic screws have the greatest holding power.

The Fully Softened Shear Strength of Lake Agassiz Clays

2020 ◽  
Author(s):  
Iván A. Contreras ◽  
Jed D. Greenwood ◽  
Aaron T. Grosser
Keyword(s):  
Shear Strength ◽  
Lake Agassiz ◽  
Fully Softened Shear Strength
Sign in / Sign up

Export Citation Format

Share Document