MECHANISM|OF CREEP DAMAGE ON STRUCTURE PLANE IN ROCK MASS

At first, this paper compares the Burgers creep model with the Bingham-Kelvin creep model. Based on the comparison, the Bingham-Kelvin creep model is employed to study the creep damage characteristics of structural plane in rock mass. Under the condition that the shear stress applied on the plane is less than its shear strength (i.e., 0s), this paper derivates the expression of shear modulus with the Bingham-Kelvin model, and defines a damage variable taking the shear modulus as variable. Based on the shear tests on mudstone, this paper further calculates the shear modulus and damage value of the structural plane under the same normal compressive stress. The results show that: (1) When 0s, the shear modulus and damage value of the structural plane vary little as the time goes, and the damage value of the structural plane is little at the first two phases, and (2) when 0s, the damage value alters suddenly some time later. The initial shear modulus increases with the increasing in the shear stress, and under higher shear stress, they reduce more quickly with time and decrease more while creep reaches to the stable phase. The creep deformation of structural plane increases with the increasing in shear stress and time, [JP3]and the damage increases more under higher shear stress when creep attains to the stable phase. [JP] 〖WT5HZ〗Key words〓〖WT〗Rock mechanics， Creep damage, Shear modulus, Structural plane, Bingham-Kelvin creep model, Mudstone 〖HT〗