小间距隧道爆破开挖动力效应数值模拟研究

Study on dynamics effect caused by blasting construction by numerical simulation for tunnels with small spacing

从爆破施工的特点入手,对小间距隧道在采用典型双侧导坑法时的爆破施工动力效应进行了数值模拟研究,给出了爆破施工在已有洞室周边产生的动力效应的一般规律,指出在爆破(后开挖洞室)开挖影响区以内,合理确定已有洞室二次衬砌施作时间的重要性,并给出了爆破施工对已有洞室稳定性影响较大的关键开挖位置。研究表明,爆破动载荷对小间距隧道围岩稳定性的影响主要表现为爆炸应力波造成围岩临空面的反射拉伸破坏,破坏较严重的是已有洞室的迎爆墙、拱脚、拱顶等部位。所得结论对小间距隧道爆破施工有一定的参考价值。

Based on the characteristic of blasting construction, the dynamic effect caused by blasting construction for the typical double side excavation method is studied by numerical simulation. The general laws of dynamic effect are proposed at the boundary of the existing tunnel. The secondary supporting time is important to the existing tunnel in the region influenced by blasting construction, and the key locations which blasting construction influences the stability of existing tunnel are given. The analysis shows that the dynamic effects caused by blasting on the stability of surrounding rock of existing tunnel are mainly the tensile damage at the surface of surrounding rock caused by blasting stress wave. The most serious damage locates at the face-blast-wall, arch feet, arch roof of the existing tunnel. The results provide some reference for the blasting construction of the tunnels with small spacing.