Excavation disturbance response of deep-buried tunnel with novel dynamic anisotropic mechanical model and failure degree index

Abstract

The current research on the failure theory of surrounding rock failure caused by excavation disturbance of deep buried engineering is seriously insufficient, especially under the combined conditions of true three-dimensional stress and excavation disturbance, which leads to unclear excavation responses and engineering disasters. Therefore, this study carried out true triaxial disturbance tests to investigate the mechanical characteristics of rock under excavation unloading and disturbance in deep engineering. Calculation methods for the anisotropic Young’s modulus, cohesion, friction angle and dilation angle during rock fracture were proposed to reveal their evolutions. A dynamic anisotropic mechanical model reflecting rock degradation induced by true triaxial disturbance was further established, and the numerical program was implemented in finite difference software. Numerical simulation results with proposed model were basically consistent with laboratory tests and deep engineering field monitoring data. Based on numerical simulation, a rock disturbance fracture degree index was proposed to quantitatively evaluate the fracture location, range and failure degree of surrounding rock after engineering excavation disturbance. Compared with static excavation, disturbance excavation leads to larger deformation of surrounding rock, larger depth and degree of failure, and more energy released.