Shear Strength of Sand under a Vibrating Load

Abstract

This paper presents some test results on the strength of saturated and dry sands under drained triaxial vibratory loading conditions. In these tests the loadings are controlled so that the values of τ_d/σ_Nd' are in accord with the angle of mobilized internal friction, φ_mo', where τ_d is the dynamic shearing stress on the shear plane and σ_Nd' is the dynamic normal stress. The triaxial vibrating tests are carried out under the following loading conditions: the amplitudes of lateral confining pressures are kept constant at 0.1, 0.2, 0.3, and 1.0 kg/cm^2, and the amplitude of axial pressure is controlled so that the angle between the normal stress and the resultant vibrating stress is in accord with φ_mo'. The comparisons between the test results on saturated sands under drained triaxial vibratory loading conditions and those of static triaxial compression tests are made. The dynamic strength of sands depends on various factors, and tentative conclusions obtained are as follows. (1) The internal frictions in terms of the effective stress of sand under the vibratory loading conditions decrease with the increasing of the amplitude of lateral confining pressure and the frequency of vibration. (2) The strength of sand under vibration decreases with the increasing of the initial void ratio but this tendency of strengthloss is not observed for the larger pressure amplitude.