共面闭合非贯通节理岩体贯通机制和破坏强度准则研究

STUDY ON FRACTURE MECHANISM AND CRITERIA OF FAILURE STRENGTH OF ROCK MASS CONTAINING COPLANAR CLOSE DISCONTINUOUS JOINTS UNDER DIRECT SHEAR

简述共面闭合非贯通节理岩体的破坏机制及其贯通强度依赖于节理和岩桥的特性,阐述现有的共面闭合非贯通节理岩体的强度准则及其不足。研究直剪应力状态下共面闭合非贯通节理的受力特点,提出共面闭合非贯通节理岩体破坏机制,引入起裂角,在此基础上建立含起裂角的共面闭合非贯通节理岩体贯通破坏强度准则。通过与前人的试验进行对比,结果表明提出的破坏机制能较好地解释试验现象,理论计算的峰值强度与试验实测值吻合较好。

Rock masses containing coplanar close discontinuous joints are commonly found in nature, and their failure mechanism and strength strongly depend on the properties of joints and rock bridges, which are defined as the areas between joints. Several shear failure criteria of the rock mass are viewed and compared, and their weaknesses are pointed out. The mechanical behaviors of brittle rock mass containing coplanar close discontinuous joints under shear condition are analyzed, and the failure mechanisms of the rock mass are proposed. The rock mass may fail in three ways, failure in tension, failure in shear, and failure in mixed tension and shear. A modified criterion of failure strength of the rock mass is proposed for failure in mixed shear and tension. The equation of the shear strength contains the properties of geometry and mechanics of joints and rock bridges. Shear initiation angle as a new parameter is introduced firstly and also is contained in the equation. The failure mechanism can explain the phenomenon in direct shear test, and the calculated results according to the modified criterion of failure strength agree well with experimental results.