Experimental Study of Confining Pressure Initiated by Tectonic Force

An experimental study of the confining pressure, i.e. additional hydrostatic pressure initiated by the tectonic force is presented. The experimental progress is that the σ₁ is gradually increasing from 0 in a limiting movement (ε₁=0) in the σ₁ direction and the speed rate of the accelerating load is 0.4 MPa·s^-1 in the lateral and level directions. When σ₂= σ₃ < 200 MPa, Δσ_l is nearly lacking, Δσ_l is increasing at a high speed only when the horizontal force reaches 250-380 MPa, and Δσ_l almost ceases to increase at the level force of 380 MPa. It is calculated that the tectonic force can produce the confining pressure which is gradually increasing with σ₂= σ₃ before it reaches 380 MPa in an experiment. It is supposed that the horizontal force is almost all transformed into the confining pressure with the increase of the creep deformation of rocks.