การวิเคราะห์แนวการวิบัติและการประเมินเสถียรภาพของมวลหินโดยรอบอุโมงค์ภายใต้แรงดันภายในสูง

Abstract

This study focuses on evaluate the stability of rock mass under high internal pressure due to gas storage. The reasonable failure planes from element free Galerkin method (EFG) considered from influenced factors are used to evaluate. The scaled-down model is used to validate by varying the in-situ stress ratio (k) 0.5, 1 and 3. From the analysis, It is found that the in-situ stress ratio has influence on the crack initiation and the direction of failure plane. The results from this study are compared with previous study. Those results are good agreement. Moreover, the EFG is extended to analyze the prototype model by varying depth, in-situ stress ratio and the tensile strength of rock. It reveals that the in-situ stress ratio equal and 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.