Experimental Studies on the Rheological Properties of Marble Rock Mass

This paper puts forward and applies the method of preparation and test of rock specimen combining geomechanical analysis with mechanical process simulation and mechanical parameter control.Typical marble standard specimens acquired from the surrounding rock of the diversion tunnel in a hydropower station were prepared into fractured rock mass replica specimens by simulating the geological-mechanical processes of the rock mass formation.Uniaxial compression creep,relaxation and unloading tests as well as tri-axial compression creep tests were performed on the replica specimens to reveal the rheological properties of marble rock mass.According to the test results,the rheological properties can be characterized by the Nishihara model from which the rheological parameters and long-term strength can be calculated.The rock mass strength showed some time-dependent weakening characteristics; comparing with the instantaneous strength parameters,c∞ decreased by 60% and φ∞ decreased by 14%.The time-dependent shear strength weakening effect of rock mass was related to the ground stress of the rock mass,and it was more significant under low ground stress than that under high ground stress.