Study of failure behavior of rock mass around circular tunnel under excavation process by element free-Garlerkin method

Abstract

This study aims to evaluate the stability of rock mass under high internal pressure due to gas storage. The reasonable failure planes by element free Galerkin method (EFG) considered from influenced factors are used to evaluate. Before the stability of rock mass is evaluated, the EFG is developed and analyzed the failure planes by varying the in-situ stress ratio 0.5, 1 and 3 with scaled down model. The obtained failure paths from this study and previous study are good agreement The EFG is extended to analyze the prototype model. It is found that k equal or greater than 1 is suitable for assessing the potential for the site rock to host pressurized underground tunnel at initial stage of design. For case k less than 1, the failure plane move up to ground surface therefore that case will be evaluated stability. Limit equilibrium analysis with proposed failure plane is adapted to evaluate the stability. From evaluation stability, preliminary design chart is obtained for tunnel under internal pressure by considering effect of depth, radius of tunnel, level of pressure and overburden pressure. The evaluation on the factor of safety can be useful for preliminary design stage for pressurized underground tunnel.