爆破荷载作用下青岛胶州湾海底隧道覆盖岩层稳定性分析

以青岛胶州湾海底隧道为背景,采用国际上常用的计算模式模拟爆破施工荷载,根据ABAQUS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,依据不同围岩类型和岩层覆盖厚度设计值选取隧道左、右线典型段;采用有限单元法分析了覆盖岩层各监测点的振动速度、加速度变化趋势。数值分析结果表明,各测点的振动速度、加速度时程曲线均满足隧道爆破变形规律。根据隧道围岩振动破坏准则,计算所得的最大水平、垂直振动速度均小于规范要求的临界值,且爆破作用影响范围远小于隧道覆盖岩层设计厚度,所以岩层覆盖厚度设计值满足爆破工程稳定性和安全性要求。同时,考虑到隧道选线的经济合理性,提出了爆破施工荷载作用下隧道顶板厚度设计参考值,并进行了验证,对类似工程具有一定的指导意义。

STABILITY ANALYSIS OF ROCK COVER OF QINGDAO KIAOCHOW BAY SUBSEA TUNNEL UNDER EXPLOSIVE LOADS

In order to analyze the effects of the explosive load on the rock cover of Qingdao Kiaoshow Bay subsea tunnel,a calculating model is used;and the explosive load is imposed on surrounding simultaneous blast holes with equivalent stress. Left and right typical segments are chosen according to different surrounding rock types and rock cover thickness;and 3D finite element analysis is performed by ABAQUS. By means of analysis of velocities and accelerations at survey points,it is easy to draw the conclusion that each velocity-time curve and acceleration-time curve can satisfy the subsea distortion rule,and the level and vertical rapidity peak values satisfy those of subsea tunnel failure criterion. The influence scope under explosive load is much less than design rock cover. Then,the design rock cover is steady under such explosive load. At the same time,the referenced rock cover is offered in view of the economical factors,and the value is testified finally.