动静荷载对邻近巷道裂纹缺陷扰动的模拟实验

为了探究动静组合应力场作用下邻近巷道背爆侧裂纹缺陷的扩展规律，采用动静加载透射式动态焦散线方法进行了模拟实验，并结合裂纹尖端的动态应力强度因子和能量释放率进行了分析。实验结果表明:在动静荷载作用下，邻近巷道背爆侧裂纹缺陷处也成为巷道主要扰动区，且爆炸荷载对背爆侧预制裂纹的起裂起主导作用；p=0.2 MPa时的相同动静组合应力场中，背爆侧预制裂纹的扩展位移差异与裂纹的倾角有关，当θ=75°时，爆炸应力波无法驱动裂纹起裂；在相同爆炸荷载作用下，θ=30°时，较小竖向荷载对裂纹的扩展具有抑制作用，且抑制作用随所施加的竖向荷载增加而增大，当p=0.4 MPa时，裂纹无法起裂；裂纹最终扩展位移，与裂纹尖端动态应力强度因子在极大值上下振荡变化的持续时间，或在裂纹扩展阶段能量释放率积累量，呈正相关。

Simulated experiment of disturbance effect on crack defects of adjacent tunnel under dynamic and static load

To explore the mechanism of crack expansion in the adjacent tunnel under the influence of the combined stress field, a simulated experiment was carried out adopting the blast loading and static loading transmission of the dynamic caustics, and the result was analyzed combined with dynamic stress intensity factors and the energy release rate of the crack tip. The experimental results show that the region where cracks are located in the back-blast side of the adjacent model-tunnel is also the main disturbance zone of the tunnel and that the explosion load plays a leading role in inducing crack initiation in the combined stress field formed by the less vertical pressure and the explosion load. In the same combined stress field, with p=0.2 MPa, the prefabricated crack extension displacement is associated with the angle of the crack and, with θ=75°, the explosive stress wave cannot induce crack initiation. Under the effect of the same explosive stress wave, with θ=30°, the less vertical stress within a certain range has an inhibitory effect on the propagation of the crack, and this effect increases with the vertical pressure increase applied in the neighboring roadway. With p=0.4 MPa, the crack cannot induce crack initiation. Eventually the displacement of an extended crack occurred, which is positively correlated with the duration time of the dynamic stress intensity factor around its maximal value or with the accumulated value of the energy release rate in the stage of the crack propagation. The results of the present study will have a guiding significance for practical engineering in mining industry.