Application of block theory in underground cavern rock stability

Abstract

Based on Bai-Se hydraulic engineering, a large-scare hydraulic engineering in China, application methods of Block Theory to underground cavern are introduced, including unlocated, located and stochastic block analysis, as well as block morphologic display, block stability analysis and reinforcement measures suggestion. In unlocated block analysis, block geometric figure is analyzed by assuming block maximum edge length according to joint average length by investigation in situ. Appearance of maximum key block in cavern is analyzed and shown, so as to determine key blocks which should be considered in support design. Based on block geometric figure and joint shear strength, block stability is computed, anchor force is suggested in order to assure block stable. In located block analysis, actual morphology of blocks, including concave blocks are analyzed and displayed according to investigation of joints in cavern, stability of block is analyzed and anchor support design program is checked subsequently. In stochastic block analysis, simulating net of joint and stochastic block in excavation face are studied and shown. During the study of application of key block theory in underground cavern, some new technologies are developed such as block morphology analysis by assuming block maximum edge length, concave block analysis and display, and especially stochastic block analysis. These new technologies may promote application of block theory in rock engineering.