Study on dynamic crack initiation and propagation behavior of surrounding rock of adjacent roadway

In order to study the mechanical behavior characteristics of dynamic crack initiation and propagation of surrounding rock of adjacent roadway under impact load, with the help of a new digital laser dynamic caustics experimental system, a rock-like medium material PMMA was used to make a double-section roadway model for impact tests, and the crack propagation simulation was carried out based on the ABAQUS numerical simulation platform. The results show that when the pre-crack deflection angle α of adjacent sections is 45°, 22. 5°, 0°, -22. 5°, -45°, the dynamic stress intensity factor are different when the cracks were initiated. The dynamic stress intensity factor change after crack initiation has a "platform section" with a duration of about 160 μs. When the right crack gradually moves away from the left cross-section, the crack propagation speed of left crack after initiation will increase. When the dynamic crack initiation and propagation of the double-section roadway, the adjacent sections will affect the dynamic stress intensity factor and propagation speed to a certain extent. When the tip of the right crack is close to the left crack, the latter's crack initiation toughness is reduced, that is, it is easier to crack.