Dynamic Behaviour of Soil (II)

High Speed Tri-axial Compression Test

Abstract

In previous paper, we found that the fracture strength of soil under the dynamic load increased with logarithm of the loading speed v, and that the fracture of soil was due to the shearing stress and the limit-equilibrium formula τ=σ⋅tanφ+c was valid at high speed. In this paper, we report the results of the high speed tri-axial compression test of soil, applying the side pressure σ₃ and measuring the normal compression stress σ₁.
(1) The fracture phenomenon are same to uniaxial compression test and are due to the shearing stress. (2) The fracture stress σ₁ increases with log v until the critical velocity decreases with the increase of side pressureσ₃. (3) With using the Mohr' circle (Fig. 3), we determine the cohesion c and the angle of internal friction φ, and with this result c mainly increases with the velocity v and φ slightly increases or oppositly decreases with v (Fig. 4)