EXPERIMENTAL STUDY ON TIME EFFECT OF MUDSTONE MECHANICAL PARAMETERS WITH NEW CREEP APPARATUS

The deformation modulus(E),cohesion(c)and internal friction angle()are three basic mechanical parameters in the process of rock creep. They can gradually degrade with time and stress. This paper improves the present creep apparatus and develops a new manmade fivejointed uniaxial creep apparatus. The new apparatus can test five samples simultaneously under the different conditions for their mechanical parameters(E,c,and ). The degrading regularities of above three parameters of mudstone collected from Qinyuan coal mine plant in Baoji Shanxi are investigated in the process of creep with this new creep apparatus. The results show that the dependent variable values of E,c, and  are degraded exponentially with the viscoplastic strain, as the independent variable. The failure values of E,c and  are calculated. The paper analyzes the relationship of E,c, and  with the viscoplastic strain. Three coupling functional equations are obtained for indicating the influence of E,c, and  on the stress()and time(t), respectively. This paper lays a foundation for further establishment of unsteady mudstone constitutive model．