浅埋小净距隧道爆破损伤探测及数值模拟分析

为了研究爆破荷载对浅埋小净距隧道围岩造成的损伤影响，以济南顺河快速路南延工程浅埋暗挖段为工程背景，通过LSDYNA软件将建立的各向异性动态损伤本构用于隧道爆破的损伤数值模拟，研究炮孔周围的损伤范围；并基于声波测试原理，对浅埋小净距隧道围岩的损伤进行了现场探测。结果表明:在数值模拟中，单个炮孔爆破形成的最大损伤影响半径为0.58 m，最大损伤影响深度为1.88 m，根据岩体的损伤破坏阈值，岩体的破坏水平范围可达0.14 m，破坏深度为1.70 m；根据现场探测，中夹岩受双线隧道交替爆破开挖其损伤程度较围岩其他部位要高，爆破开挖对隧道围岩造成的损伤范围在0.50 m左右，与模拟结果相接近，验证了各向异性动态损伤本构的准确性。研究成果对浅埋小净距隧道的爆破开挖和损伤控制具有一定指导作用。

Detection and numerical simulation of blasting-induced damage in shallow-buried twin tunnels with small spacing

In order to study the damage effect of blasting load on the surrounding rock of shallow-buried small spacing twin tunnels, the shallow-buried tunneling section of the south extension project of Shunhe Expressway is taken as the engineering background. Firstly, based on the dynamic damage evolution and Hoffman failure criterion, an anisotropic dynamic damage constitutive model for rock materials is established. Then, by using the secondary development function of the LSDYNA software, the constitutive model is applied to the numerical simulation of the tunnel blasting damage. Finally, based on the acoustic wave measurement theory, the wave velocities in the surrounding rock of the shallow-buried small spacing twin tunnels before and after blasting were measured by using non-metallic ultrasonic detectors, and the damage of the surrounding rock is evaluated from changes in wave velocity. The applicability of the anisotropic dynamic damage constitutive model and the accuracy of the numerical results are verified by comparing the numerical simulation results with the field test results. The numerical simulation results show that the maximum damage radius of single-hole blasting is 0.58 m, and the maximum damage depth is 1.88 m. According to the failure threshold of the rock mass, the horizontal failure range of the rock mass can reach 0.14 m, and the failure depth is 1.70 m. According to the field test, the damage degree of the middle intercalated rock is higher than that of the other parts of the surrounding rock in the alternate blasting excavation of the double track tunnel. The damage range of the surrounding rock caused by blasting excavation is about 0.50 m, which is close to the simulation results, and verifying the accuracy of the anisotropic dynamic damage constitutive model. The research results have a certain guiding role on the blasting excavation and damage control of shallow-buried twin tunnels with small spacing..