Analytical solution for a circular roadway considering the transient effect of excavation unloading

The rocks surrounding a roadway exhibit some special and complex phenomena with increasing depth of excavation in underground engineering. Quasi-static analysis cannot adequately explain these engineering problems. The computational model of a circular roadway considering the transient effect of excavation unloading is established for these problems. The time factor makes the solution of the problem difficult. Thus, the computational model is divided into a dynamic model and a static model. The Laplace integral transform and inverse transform are performed to solve the dynamic model and elasticity theory is used to analyze the static model. The results from an example show that circumferential stress increases and radial stress decreases with time. The stress difference becomes large gradually in this progress. The displacement increases with unloading time and decreases with the radial depth of surrounding rocks. It can be seen that the development trend of unloading and displacement is similar by comparing their rates. Finally, the results of ANSYS are used to verify the analytical solution. The contrast indicates that the laws of the two methods are basically in agreement. Thus, the analysis can provide a reference for further study. (C) 2016 Published by Elsevier B.V. on behalf of China University of Mining & Technology.