SOME ADAPTATIONS OF CLASSICAL PLASTICITY THEORY FOR SOIL STABILITY PROBLEMS

A REVIEW IS PRESENTED OF THE CURRENT CAPABILITIES OF PLASTICITY THEORY IN PREDICTING THE GENERAL FAILURE OF SOIL MASSES. EMPHASIS IS PLACED ON THE STRENGTH OF SOIL RATHER THAN YIELDING OR NON-LINEAR STRESS-STRAIN BEHAVIOR PRIOR TO REACHING PEAK STRENGTH. A LOADING PATH METHOD OF ANALYSIS IS USED TO OBTAIN THE MAXIMUM AND/OR THE FINAL COLLAPSE LOAD. THE GENERAL ASSUMPTION, IMPLICIT IN MOST METHODS OF STABILITY ANALYSIS, THAT THE COLLAPSE LOAD OF A SOIL MASS IS INDEPENDENT OF LOADING PATH IS DISCUSSED. THE ADVANTAGES OF THE LOADING PATH METHOD ARE (1) IT MAY BE THE ONLY FEASIBLE APPROACH FOR ASSOCIATED FLOW RULE MATERIALS, (2) IT REMOVES UNCERTAINTY REGARDING UNIQUENESS FOR MATERIAL HAVING A NON- ASSOCIATED FLOW RULE AND (3) THE LOAD DEFORMATION BEHAVIOR PRIOR TO COLLAPSE MAY BE A CONTROLLING FEATURE IN PRACTICE.