舟山灌门水道海底隧道钻爆法施工稳定性分析

Stability analysis of Zhoushan subsea tunnel with drill-and-blast construction method

以舟山灌门水道海底隧道为背景,依据地质资料,选取隧道典型横断面来研究钻爆法施工时围岩的稳定性。由典型横断面的几何参数和地质资料构建数值计算模型,采用国际上常用的计算模式模拟爆破荷载,根据FLAC3D动态计算的特点,将爆破荷载以等效应力的方式加载于模拟炮孔之上。数值计算结果表明,各关键点的位移、振动速度、加速度-时程曲线均满足隧道爆破变形规律,且振动速度峰值均小于规范要求临界值,爆破作用影响范围小于岩石覆盖层建议厚度,验证了岩层覆盖厚度建议值和爆破方案的合理性。最后,为了弄清岩石覆盖厚度和炸药量对围岩稳定性的影响,给出了不同岩石覆盖厚度和炸药量情况下的计算结果。所得结论对后续施工和类似工程具有一定的指导意义。

In order to analyze the stability of surrounding rocks of Zhoushan subsea tunnel with drill-and-blast construction method, a typical cross section is chosen according to geological information. A model for numerical analysis is established according to geometrical parameters and geological information.of the typical cross section. An international calculating mode is used to simulate explosive load, and the explosive load is imposed on simulative blast holes in equivalent stress form due to characteristics of dynamic calculation of FLAC^3D. By means of analysis of velocities and accelerations of survey points, it is easy to draw the conclusion that each velocity-time curve and each acceleration-time curve satisfy the explosive distortion rule; and the peak values of vibration velocities are less than failure criterion of rock. The influence scope under explosive load is within the recommendatory thickness of rock overburden. Then the rationality of recommendatory thickness of rock overburden and explosive scheme is validated. Eventually, in order to define the effects that are imposed on the surrounding rocks by the thickness of rock overburden and charge amount, the calculation results under different conditions are presented. Some conclusions are drawn so as to benefit the future construction and other analogical rock engineerings.