节理连通率对岩体力学特性影响的细观研究

采用等效岩体（ERM）技术，将节理和岩块分别用光滑节理模型及颗粒体模型表征，构建含不同节理倾角、连通率的等效岩体模型。结合试验结果，从细观力学角度开展单轴压缩条件下节理连通率对岩体强度、破裂机制、能量演化等力学特征影响的定量研究。研究发现，当节理方向与加载轴向呈一定夹角时，岩体表现出沿岩桥连线方向的贯通破坏趋势，尤其当节理倾角? = 30°，连通率L = 0.8时，岩体破坏表现出岩桥复合贯通破坏模式。在该类节理倾角(? = 30°)条件下，随节理连通率增大，岩体表现出的主要力学特征为：（1）峰值抗压强度呈不断降低趋势；（2）微破裂总数不断下降，但张拉型微破裂所占比例逐渐提高。微裂纹进一步集中在不同层间节理尖端岩桥连线上产生；（3）声发射（AE）事件产生时间在整个加载阶段逐渐分散，声发射事件总数及破裂强度分布范围、均值、标准差等均不断减小；（4）峰值应变能及峰后应变能、动能变化率降低，峰后摩擦能增速放缓，试样破坏所需的外界做功逐渐降低。

Meso-research on mechanical properties of rock mass affected by joint connectivity rate

By using equivalent rock mass(ERM) technique, the ERM models containing diverse joint dip angle and connectivity rate are constructed, in which the joint and rock block are represented by smooth joint model and bonded particle model, respectively. Combining with test result, the effect of joint connectivity rate on strength, fracture mechanism and energy evolution of rock mass under the condition of uniaxial compression, is quantitatively investigated from meso-mechanical viewpoint. Research shows that when an angle presents between joint and load direction, rock mass behaves as the tendency of coalescence failure along the connecting direction of rock bridge. Especially with joint dip angle α of 30° and connectivity rate L of 0.8, rock mass exhibits composite coalescence failure of rock bridge. Under the condition of the joint dip angle α of 30°, with increase of joint connectivity rate, rock mass exhibits the following mechanical behaviors: (1) The peak compressive strength continually decreases. (2) The amount of microcracks decreases, but the ratio of tensile microcracks increases. Meanwhile, microcracks gradually generate on the rock bridge line between different level joint tip. (3) The occurrence time of acoustic emission (AE) event during the entire loading stage gradually disperses. The amount of AE event as well as the distribution range, mean value and standard deviation of fracture magnitude decreases. (4) The peak strain energy as well as the post-peak change rate of strain and kinetic energy reduces. The growth of post-peak frictional energy slows down. The required work supplied by exterior to destroy the specimen reduces.