相邻巷道围岩动态裂纹起裂与扩展行为研究

为研究冲击荷载下相邻巷道截面周边岩体动态裂纹起裂与扩展的力学行为特性，借助新型数字激光动态焦散线实验系统，使用类岩石介质材料PMMA制作双截面巷道模型进行冲击实验，并基于ABAQUS数值模拟平台对裂纹扩展过程进行仿真。结果表明:当相邻截面预制裂纹偏转角度分别为45°、22.5°、0°、-22.5°、-45°时，裂纹起裂时的动态应力强度因子不同。裂纹起裂后的动态应力强度因子变化有一个“平台段”，持续时间为160 μs左右; 当右侧裂纹逐渐远离左侧截面时，左侧裂纹起裂后的扩展速度会有所增大。双截面巷道动态裂纹起裂扩展时，相邻截面会在一定程度上影响动态应力强度因子和扩展速度。右侧裂纹尖端靠近左侧裂纹时，后者的起裂韧度降低，即较容易起裂。

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.