Numerical study on the deformation and failure of soft rock roadway induced by humidity diffusion

In underground space engineering, the humidity in the environment has a great influence on the structural performance of soft rock roadway. It not only changes the stress state of rock mass, but also weakens the physical and mechanical properties of surrounding rock, resulting in many accidents such as swelling deformation and even collapse of the roadway. In this paper, the deformation and failure process of soft rock roadway in high humidity environment are simulated by using the humidity diffusion-deformation-fracture coupling model based on the finite-discrete element method (FDEM). Firstly, the coupling model is verified through two simple examples with analytical solutions. Then, the humidity diffusion and floor heave of soft rock roadway after excavation are studied by using the coupling model. The results show that only the humidity of the surrounding rock surface changes greatly at the beginning of excavation and the roadway floor heave caused by humidity is small but with a large change rate. However, with further diffusion of humidity, the displacement of the floor increases slowly at a constant rate. Besides, several main factors affecting floor heave are studied, including humidity swelling coefficient, initial elastic modulus, and initial humidity of floor. Finally, the coupling model is used to simulate the roadway failure process induced by humidity diffusion. The numerical results provide a better understanding of the deformation and failure behavior of soft rock roadway in high humidity environment.