Analytical Approach for Evaluating the Dynamic Self-Bearing Capacity of Tunnels

The self-bearing capacity of tunnels possesses a dynamic evolution process. However, there is a limited advanced knowledge to evaluate the dynamic self-bearing capacity of tunnels quantitatively. In this paper, the time-dependent self-bearing factor of the tunnel surrounding rock is proposed, and an analytical approach for the circular excavations is developed. In this paper, the rock mass is regarded as a viscous material with a distinguishable strain-strengthening property. The stress states around circular excavations are determined using the Drucker-Prager criterion and the power-hardening constitutive model. Then, the Burger-creep viscoplastic model is introduced to evaluate the time-dependent deformations. Finally, the formula of a time-dependent self-bearing factor of tunnels is obtained. The sensibilities of time-dependent self-bearing factor and time-dependent deformation of tunnels to the incorporated model parameters are investigated in depth. Effects of incorporated model parameters on time-dependent self-bearing factor and time-dependent deformation of tunnels are consistent with their physical meanings. This paper provides an analytical approach for quantitatively evaluating the dynamic evolution process of the self-bearing capacity of tunnels.