Analysis of Crack Propagation Characteristics of Rock-like Material with Double Closed Cracks Under Uniaxial Compression

In order to explore the influence of the length and dip angle of the rock bridge on crack initiation, propagation and coalescence, based on the rock-like material uniaxial compression laboratory test, the particle flow program PFC(2D)was used to simulate the uniaxial compression of rock-like specimens with double prefabricated closed cracks, and the strength characteristics and crack propagation and coalescence laws of specimens with different prefabricated closed cracks were obtained. The numerical results showed that: Changing the length of the rock bridge and keeping the dip angle constant, when the length of the rock bridge was 13 mm, the double cracks had 2 penetrations, and the other lengths had only 1 penetration. As the length of the rock bridge increased, the peak stress appeared to increase first and then decrease, while the crack initiation stress did not change much. Changing the dip angle of the rock bridge and keeping the length constant, when the rock bridge dip angle was - 75 degrees and - 15 degrees, there were 3 penetrations; when the rock bridge dip angle was - 45 degrees, there were 4 penetrations; when the rock bridge dip angle was 15 degrees, 45 degrees and 75 degrees, only 1 penetration was formed. As the dip angle of the rock bridge increased, the peak stress appeared to increase first and then decrease and then increase, and the crack initiation stress appeared to decrease first and then increase.