Mechanical properties of rock with pre-cracks anchored by constant resistance and large deformation cables based on particle flow codes

The mechanical properties of rock with pre-cracks on the free surface of roadways are anchored using a new type of constant resistance and large deformation (CRLD) cable. Taking the number of cracks as a variation, the PFC(Particle Flow Codes) software was used to assess the servo control of pallet to equivalent characteristics of CRLD cable. The results showed that owing to the constant resistance support effect of the pallet, new cracks sprout from both ends of the pallet and in the middle and deep areas and then propagated to form large through-cracks. The integrity of the rock mass near the pallet was better, and the smaller the number of pre-cracks, the larger this intact rock mass was. In addition, the Mori-Tanaka method better describes the variation in the anchored rock strength according to the number of pre-cracks by introducing parameters a and b, which represent the pallet reinforcement effect and crack correction, respectively. Finally, the energy absorption evolution of the constant resistance pallet was divided into uniform and non-uniform energy absorption stages. As the number of pre-cracks increased, the proportion of the uniform energy absorption stage increased and that of the non-uniform absorption stage decreased. As the number of pre-cracks increased, the slope S of the uniform-fitted energy ab-sorption stage increased and the growth rate of S first increased and then decreased.