基于多源地震干涉法隧道断层位置预测数值模拟

西部山区在建或即将修建的大量隧道都具有高地应力特征,如何提高高地应力隧道超前地质预报的准确性是当前工程界面临的一大关键难点,而地应力增加是岩体波速增加的主要因素之一。采用多源地震干涉法模拟了在断层波速一定的条件下围岩波速和断层倾角变化对隧道掌子面前方断层位置识别的影响。数值模拟结果表明:围岩波速和断层倾角的增加会导致预报的断层位置比实际位置更接近掌子面,计算结果间接表明了地应力对识别断层位置的影响。通过二元二次函数回归分析拟合出一个含地应力和断层倾角的修正公式,依据修改公式,对白马隧道高地应力洞段掌子面前方不良地质体进行了超前地质预报,隧道现场开挖结果与修正后的预报结果基本一致。

Numerical simulation of predicting location of a tunnel fault based on multisource seismic interferometry

A large number of tunnels under construction or to be built in the western mountains are characterized by high in situ stress. How to improve the accuracy of tunnel advance geological prediction is a key and difficult problem for underground engineering construction in high in situ stress area. In the paper, the multisource seismic interferometry was used to predict fault location at different surrounding rock wave velocities and dip angles of the fault when the fault wave velocity was constant. Numerical simulation results show that the increase in surrounding rock wave velocity and fault dip will make the predicted fault position closer to the tunnel face than the actual location. The calculation results indirectly show the influence of in situ stress on identifying fault location. A modified formula including in situ stress and fault angle is fitted through binary quadratic function regression analysis. According to the modified formula, the advance geological prediction of the bad geological bodies in front of the high in situ stress tunnel section of Baima Tunnel was carried out. The actual excavation results are consistent with the revised forecast results.