开挖爆破荷载作用下高应力公路隧道岩爆动力灾变机理与数值仿真研究

More attention is paid to the rock blast mechnism and its numerical simulation technology of high stress road tunnel under excavation blasting loads in this project.The rock tests, which with one crack or few cracks cut in the samples, are carried out under different unloading rate, cyclic loading,and SHPB impact test is also carried out, the dynamic crack propagation criterion is proposed by study the crack initiation, propagation and arrest from the perspective of mechnics. The excavation blasting stress wave in the disturbed surrounding rock mass is monitored and analysised,and the relationship between the crack initiation and the excavation blasting in time and space is also analysised by using digital borehole television technique. By introducing the probability distribution with the failure mode to simulate the heterogeneity and defect distributed of rock material, a rock damage mechanics model, which the element can be failed in compliance with a probability distribution, is put forward and verified. Following, the development of finite element and the meshless method (FEM-SPH) coupled numerical simulation technology are finished to simulate the rock blast induced by the excavation blasting loads of the road tunnel under high stress. The research results will be very helpful to the interpretation of the mechanism of rock blast and its prediction and prevention, and it also has a huge scientific value and potential engineering applications.

本项目紧密围绕开挖爆破荷载作用下高应力公路隧道岩爆动力灾变机理与数值仿真技术开展深入细致的研究。通过开展含预制裂隙岩石试样的不同卸荷速率、循环荷载试验，同时开展SHPB冲击荷载试验，分析试样断裂破坏特征，研究裂纹起裂与扩展的力学机理，提出循环荷载及冲击荷载下裂纹动态扩展判据；开展开挖已扰动围岩中爆破应力波的采集及信号处理，采用数字钻孔摄像探测围岩裂隙发育情况，分析裂隙发育与开挖爆破在时间与空间上的关系，通过引入概率特征来表征岩石材料的分散性，建立围岩带失效模式的概率型损伤力学模型；在上述研究基础上，开发并应用有限元－无网格法（FEM-SPH）耦合数值仿真技术，实现开挖爆破荷载作用下高应力公路隧道岩爆灾变过程的数值仿真。研究成果有助于对岩爆机理的解释和岩爆灾害的预防，具有十分重要的科学意义和工程应用价值。

项目围绕高应力公路隧道岩爆产生机理与灾害防治技术，通过室内试验、现场监测、理论分析与数值仿真相结合的综合研究手段，在岩石裂纹动态演化、爆破开挖应力波传播规律与影响、岩爆判据与破坏范围计算、公路隧道岩爆防治技术等方面取得了系列成果。应用岩土细观实验技术，开展水平和垂直层理方向加载条件下岩石裂纹演化的细观尺度观测，分析天然岩样和预制双裂纹试样破坏过程的细观表现特征，得到了水平和垂直层理方向加载条件下试样裂纹起裂、扩展和破坏模式的规律，并对岩石细观损伤变量定义方法进行了分析和讨论。通过扩展有限元与有限元的耦合分析技术，实现了岩石裂纹扩展不连续位移的模拟，据此模拟岩石静态裂纹和裂纹动态扩展，并根据公路隧道围岩能量分析和裂纹扩展分析，得出岩爆的大致区域，然后结合岩石裂纹断裂力学分析，得到岩爆发生的裂纹形成和演化，从而实现了岩爆破坏范围的计算。通过对公路隧道爆破开挖振动信号进行去噪分析和频谱特性分析，得到开挖爆破应力波频率分布特点，以及爆破药量、传播距离和隧道空间位置对爆破应力波频谱特性的影响规律，实现了爆破开挖应力波对隧道围岩影响的评估。揭示了高应力公路隧道开挖围岩变形与应力分布规律，提出了软岩公路隧道优化施工工法和支护设计，科学合理地确定了软岩公路隧道支护方案和支护参数，有效改善隧道的受力状态，降低隧道岩爆灾害风险。开发了防冲击大变形预应力锚杆、公路隧道静态爆破施工技术和高应力公路隧道施工方法等技术，对公路隧道岩爆灾害进行有效防治。项目研究成果成功应用于湖北省宜巴高速公路、云南省大丽高速公路、东深供水隧洞等多个大型工程，取得了较好的效果。