Analyzing failure modes of rock mass based on statistical mechanics of rock mass

Thursday, 17 December 2015
Poster Hall (Moscone South)
Han Bao and Faquan Wu, Key Laboratory of Shale Gas and Geoengineering, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
Joints influence mechanical properties of rock mass. Based on the strength criterion of statistical mechanics of rock mass, we analyzed the four different failure modes of rock mass with a group of joints by combining with Mohr-Coulomb strength criterion. We also deduced an expression of the critical confining pressure for explaining the transformation from structure control to stress control of rock mass strength. On this basis, rock mass with a group of joints were divided into four classes according to the relations between rock mass and joints parameters. Then, the possible failure modes and their corresponding conditions were discussed. At last, the strength characteristics of diorite with a group of joints were analyzed. The results showed that the diorite belonged to class rock mass and performed significant anisotropy in compressive strength. At the condition of vertical pressure, the rock start failing after joints at the critical confining pressure of 9.12MPa. However, with the confining pressure increasing, the anisotropy of strength became weak, and the strength of diorite would convert from structure control to stress control under some particular loading directions.