基于岩桥力学性质弱化机制的非贯通节理岩体直剪试验研究

 基于岩桥力学性质弱化机制，采用带伺服系统的直剪试验仪进行试验，在5级法向应力下，对3种含齿形节理的非贯通节理岩体进行直剪试验，研究非贯通节理岩体的强度特性和变形特性。在较低的法向应力下，含起伏角较低齿形节理面的非贯通节理岩体出现破坏模式I(张拉破坏模式)。在较高的法向应力下，含起伏角较高齿形节理面的非贯通节理岩体可能出现破坏模式II(先张拉后剪切破坏模式)。相同齿形节理面形貌的非贯通节理岩体，随着法向应力增大，峰值切向位移增大，抗剪强度增大。在相同的法向应力下，随着齿形节理面起伏角增大，非贯通节理岩体的峰值切向位移减小，抗剪强度增大。非贯通节理岩体黏聚力按Jennings方法计算值大于按试验拟合值；节理面较粗糙非贯通节理岩体内摩擦角按Jennings方法计算值大于按试验拟合值。

RESEARCH ON ROCK MASS CONTAINING DISCONTINUOUS JOINTS BY DIRECT SHEAR TEST BASED ON WEAKENING MECHANISM OF ROCK BRIDGE MECHANICAL PROPERTIES

Based on weakening mechanism for rock bridge mechanical properties，at five different normal stress levels，three different rock mass samples containing discontinuous joints which are tooth-shaped asperities have been studied by laboratory shear test. The tests are conducted with electro-hydraulic servo-controlled shear system. The tests are to study both failure mechanism and strength behavior，displacement behavior of rock mass containing discontinuous joints. At lower angle of tooth-shaped asperities and under lower normal stress，the failure model I is found，which is always in tension failure model. However，at higher angle of tooth-shaped asperities and under higher normal stress，the failure model II is found，which is in first tension but final shear failure. Under the same joint appearance，with the normal stress increasing，both the shear strength and the displacement for peak shear strength raised. However，at the same normal stress，with the joint appearance increasing，the displacement for peak shear strength decreased but the shear strength raised. Moreover，all of cohesion calculated based on Jennings¢ theory is higher than the experimental results. Some of angles of friction calculated based on Jennings¢ theory are more than the experimental ones.