DYNAMIC STRENGTH CHARACTERISTICS OF SOILS

Abstract

An attempt has been made herein to study the strength of c-(D soil samples of size 6.0 x 6.0 x 2.0 cm under oscillatory shear stresses on an oscillatory shear box, in, which frequency of load application, normal stress and of pulsating stress levels can be varied. The different parameters considered include frequency of load application, number of cycles, normal stresses and pulsating shear stress. In addition, another important factor is the type of soil. A mixture of Bentonite and Solani sand at varying percentages constitute the different types of soils studied. In all, 81 tests were conducted on three types of soils namely SM, CL and CH classified according to the Indian Standard IS:1459-1971. Three different values of frequencies, normal stresses and pulsating shear stresses have been considered during the testing. Results indicate that - (i) The strcngth of soil is reduced in dynamic tests. (ii) - Reduction in strength is only for the cohesion parameter and the friction parameter remains the same both in static and dynamic tests. (iii) Larger the frequency of dynamic loads, larger is the reduction in strength in the range 0.175 to 0.7 cps. (iv) Percentage reduction in strength under dynamic tests more in the case of compressible soil and minimum on silty sand.