Experimental and numerical investigation on mode I fracture properties of bedded rocks

Bedding shows great influences on the fracture properties of bedded rocks. To investigate the mode I fracture properties of bedded rocks, three-point bending tests of bedded rocks at different inclination angles of bedding are carried out. The influences of asymmetric loading coefficient, groove width and bedding strength on mode I fracture properties are then studied by numerical simulation. The laboratory test results reveal that with the increasing inclination angle of bedding, the bedding effect is reinforced which leads to the fact that mode I fracture toughness values continuously decrease and fracture modes of test samples transform from through the bedding to along the bedding. The peak values of mean height and maximum height, and the JRC values of fracture plane increase initially and decrease afterwards with the increasing inclination angle of bedding. The numerical simulation results show that the fracture load, fracture mode and microcracks' percentage of test samples are strongly influenced by the asymmetric loading coefficient, groove width and bedding strength. According to the numerical results, the fracture mode of test samples is first divided into two groups based on the principal whether the principal crack initiates at the groove. Each group is then divided into three subgroups according to the compositions of principal crack.