A Revised Formula to Compute Shear Strength of Unsaturated Soils

In the western part of Sichuan province of China, moraines are widely distributed along the Valley of Zagunao River. The moraines at high altitude have deformed constantly under the influence of precipitation. It is considered as a severe threat to the local community. By on-site geological investigation and lab experiments, the sensitivities of moraines under different saturation rates are observed. The cohesion and friction angle both have negative correlations with the saturation rates of the morainic materials. Traditional mechanical strength models for unsaturated soil analysis failed to explain the mechanical characteristics explicitly. A revised Mohr-Coulomb criterion formula with an added cohesive compensation is proposed in this research to compute the unsaturated strength. The revised criterion accurately predicts the strength and is valuable for future research of special types of breccia.

[1]  M. Boulon,et al.  Influence of humidity conditions on shear strength of clay rock discontinuities , 2013 .

[2]  Robert V. Whitman,et al.  EVALUATING CALCULATED RISK IN GEOTECHNICAL ENGINEERING , 1984 .

[3]  A. McGown,et al.  THE COLLAPSE MECHANISM IN PARTLY SATURATED SOIL , 1973 .

[4]  Laurence D. Wesley,et al.  Principle of Effective Stress , 2009 .

[5]  Yang Chao.  Discussion of fundamental principles in unsaturated soil mechanics , 2012 .

[6]  D. Fredlund,et al.  Soil Mechanics for Unsaturated Soils , 1993 .

[7]  E. Çokça,et al.  Shear strength-suction relationship of compacted Ankara clay , 2010 .

[8]  G. E. Blight,et al.  Effective Stress Evaluation for Unsaturated Soils , 1967 .

[9]  A. Bishop,et al.  Some Aspects of Effective Stress in Saturated and Partly Saturated Soils , 1963 .

[10]  D Croney,et al.  MOVEMENT AND DISTRIBUTION OF WATER IN SOIL IN RELATION TO HIGHWAY DESIGN AND PERFORMANCE , 1958 .

[11]  John Burland,et al.  Limitations to the Use of Effective Stresses in Partly Saturated Soils , 1962 .

[12]  D. Fredlund,et al.  Mathematical attributes of some soil–water characteristic curve models , 2001 .

[13]  Yongfu Xu.  Explanation of scaling phenomenon based on fractal fragmentation , 2005 .

[14]  Daichao Sheng,et al.  Review of fundamental principles in modelling unsaturated soil behaviour , 2011 .

[15]  Antonio Gens,et al.  A framework for the behaviour of unsaturated expansive clays , 1992 .

[16]  R. H. Brooks,et al.  Hydraulic Properties of Porous Media and Their Relation to Drainage Design , 1964 .

[17]  A. Gens,et al.  A constitutive model for unsaturated soils: thermomechanical and computational aspects , 2004 .

[18]  D. Fredlund,et al.  STRESS STATE VARIABLES FOR UNSATURATED SOILS , 1977 .

[19]  Nasser Khalili,et al.  Effective Stress in Unsaturated Soils: Review with New Evidence , 2004 .

[20]  Simon J. Wheeler,et al.  Coupling of hydraulic hysteresis and stress–strain behaviour in unsaturated soils , 2003 .