爆炸载荷下不同形状巷道围岩破坏规律模型试验研究

Model test study on broken rule of surrounding rock of different cross-section tunnel under blast load

采用动态焦散线试验方法,探究爆炸荷载作用下不同形状巷道周边围岩的破坏规律。试验结果表明,爆破荷载对临近巷道的影响与其形状有显著关系。在爆炸应力波作用下,巷道迎爆侧破坏明显。巷道左侧形成一条起始于炮孔中心而终止于巷道左壁的贯穿裂纹,大致沿水平方向;直墙拱形巷道左下角和矩形巷道左上、左下角形成起始于炮孔且有向这些部位扩展趋势的新裂纹。绕射应力波作用下,仅有矩形巷道背爆侧右下角出现一条扩展裂纹。以上现象说明弧形断面对应力波的卸载作用明显大于平面的。系列焦散斑图像记录了裂纹扩展过程,焦散斑大小代表裂纹尖端能量大小,裂纹扩展的过程就是能量积聚和释放的过程。

Using the test method of dynamic caustic lines,the broken rule of surrounding rocks of different cross-section roadway under blast load were studied. The experimental results showed that the effect of blast load on the adjacent roadway was significantly related to the cross-section of the roadway. The broken on the direct-blast side of the roadway was obvious under blast load. The left side of the roadway formed a penetrating crack whose direction was generally along the horizontal one,and was from the center of borehole to the left wall of roadway,Bottom left corner of the arch-wall roadway,top left corner and bottom left corner of the rectangular roadway also formed three new cracks which started from the boreholes to expanding tendency. Under the action of diffracted stress wave,only the bottom right corner of the rectangular roadway on the back-blast side,formed a propagation crack. Above phenomena indicated that the unloading effect to the stress wave on the arc section roadway is much stronger than that on the plane. A series of caustics-speckle images record the process of crack propagation,and the size of the caustics-speckle represents how much the energy accumulated in the crack tip. The process of crack propagation is the process of energy accumulation and release.