SHEAR STRENGTH OF SILTY CLAY UNDER DYNAMIC LOADS

Abstract

An attempt has been made to study the behaviour of silty clay under static, oscillatory and the combined affect of oscillatory and sustained shearing stresses. Various parameters studied during the testing programme include normal stress, oscillatory shear stress, sustained shear stress and moisture content. The tests were conducted on remoulded silty clay samples. In all, 165 tests were conducted on Dandheri silty clay under different loading used conditions and moisture contents. Frequency of loading was one cycle per second for the entire testing programme. For the soil studied the following conclusions were observed; 1. Under static loading conditions, the stress controlled shear apparatus gave higher values for cohesion when compared to those obtained using the strain controlled shear apparatus. 2. The dynamic strength of soil was less than its static strength. Reduction in strength was due to a reduction in the cohesion parameter only. 3. The static and dynamic values of the angle of internal friction (0) of the soil were found to be the same. The angle of internal friction (0) value was not dependent on the number of cycles of loading. 4. The dynamic strength of the soil studied was dependent on the number of cycles of loading till about 30 cycles, after which the strength remained constant. It was further observed that upto 30 cycles of loading, the larger the number of loading cycles smaller was the observed strength.