動荷重下における過圧密粘土の強度特性

Abstract

This is a report on dynamic strength characters of clay obtained by the triaxialoscillating compression testing apparatus in which the ambient pressure (σ3) and axialone (σ1-σ3) can be controlled seperately so as to oscillte in any same frequency and ineach optional amplitude. Undrained triaxial compression tests were carried out onnormally consolidated and overconsolidated clay under conditions that the mean ambientpressure a-s was kept constant and the mean axial one (σ1-σ3) was increased stepwisely, while axial pressure amplitude was kept constant 0, 0.2, 0.6, 1.0 kg/cm2, which is twithof ambient one, and frequency is held constant 10c. P. s. for all tests.From these tests following qualitative results are obtained.(1) The dynamic shear strength decreases with the increase of pressure amplitude.(2) The decrease of shear strength are caused by the behaviour of pore waterpressure under the oscillating pressure for the clay of which the true cohesionis negligibly small.(3) Change of the true angle of internal friction by oscillating pressure is verysmall except for the case in which the pressure amplitude is considerabllylarge compared with the static strength.