Numerical Modeling of Progressive Damage and Failure of Tunnels Deeply-Buried in Rock Considering the Strain-Energy-Density Theory

Abstract

Exploring the rock failure mechanism from an energy perspective is crucial for ensuring the safe construction of tunnels under complex geological conditions. In this study, a progressive damage and failure model of rock elements is established using the strain-energy-density theory based on the thermodynamic theory. Specifically, the rock elements are considered to have failed when the strain energy density absorbed by the element is greater than the critical strain energy density. Besides, the damage evolution of rock elements is reflected through the reduction of elastic modulus, until the element only has a certain residual strength. Based on the above theory, the calculation program of rock damage and failure is developed in FLAC3D using the FISH language. The validity of the method for simulating the process of rock damage and failure is verified through the numerical simulation of Brazilian splitting tests. Finally, the model was applied to the overload test of the geo-mechanical model of the Liangshui Tunnel on Lanzhou-Chongqing Railway. The comparison between the numerical simulation and the test results has not only confirmed that the feasibility and accuracy of the model in simulating the progressive failure process of tunnel surrounding rock under high ground stress, but also its ability to visually display the damage degree, failure scope and evolution process of the surrounding rock. The research findings are of great significance in ensuring the safe construction of tunnel and will promote the efficient development of the underground engineering construction.