深埋跨断层隧道爆破开挖动力响应规律研究

Study on Dynamic Response Law of Blasting Excavation in Deep Cross-Fault Tunnel

断层带围岩稳定性较差,往往是隧道建设的控制性区域。针对深埋隧道跨断层区域的爆破开挖围岩动力响应问题,运用有限元软件ANSYS/LS-DYNA,在高地应力和爆破荷载作用下对跨断层隧道进行三维数值模拟,研究断层的存在对隧道爆破开挖动力响应的影响规律,分析了断层带围岩的振速峰值及最大主应力附加值峰值的纵向分布特征,总结了隧道开挖后拱顶沉降规律。计算结果表明:断层对围岩的动力响应具有明显的放大作用,主要集中在断层带及其前后区域,且越靠近断层带,放大效应越明显;爆破应力波在断层与完整围岩的接触面上产生透、反射,靠近接触面左侧的围岩,其动力响应程度大于对称条件下围岩;深埋隧道开挖推进后,断层内围岩拱顶沉降大于相邻完整围岩。

Because the surrounding rock of the fault zone is of poor stability,it is often a key area for tunnel construction.Aiming at the dynamic response of the surrounding rock in blasting excavation across deep faults,the finite element software ANSYS/LS-DYNA is used to establish a three-dimensional model of a cross-fault tunnel under high ground stress and blasting loads.This model can analyze the influence of faults on the dynamic response of the surrounding in rock blasting excavation and the longitudinal distribution characteristics of the peak vibration velocity,as well as the peak value of the maximum principal stress added to the surrounding rock of the fault zone.Then the settlement law of the arch after tunnel excavation is summarized.The dynamic response of the fault to the surrounding rock has obvious amplification effect,mainly concentrated in the fault zone and its adjacent regions.The closer to the fault zone,the more obvious the amplification effect is.The blast stress wave transmits and reflects on the contact surface between the fault and the intact surrounding rock,and the surrounding rock near the left side of the contact surface responses more greatly than the surrounding rock under symmetrical conditions.After the excavation of the deep tunnel,the settlement of the surrounding rock arch in the fault is greater than that of the adjacent intact surrounding rock.