不同倾角节理组和锚固效应对岩体特性的影响

Influence of joints set with different dip angles and anchorage effect on rock mass behaviour

首先采用DDARF(discontinuous deformation analysis for rock failure)分析方法对双裂隙岩块进行单轴和双轴压缩模拟试验,研究了裂隙角度和侧向应力大小对岩块特性的影响,得到了裂隙岩块在这两种加载试验中的破坏过程、应力-应变曲线以及岩块中裂隙的起裂应力和岩块的峰值强度。在双轴压缩模拟试验中绘制了裂隙角度为45°的岩块在不同侧向压力下的强度包络线。其次,采用DDARF分析方法模拟劈裂试验中含裂隙试块的锚固效果,得到了4种不同锚固角度试块的轴向荷载–位移变化曲线和裂隙扩展规律。模拟结果与前人的类似条件下的试验结果相符良好。随后又将双裂隙试块双轴压缩模拟试验中得到的参数运用到一个地下洞室的工程实例中,用等效力学特性的方法分析对比了完整岩体和节理岩体洞室开挖完成后的破损状态的差异。最后运用DDARF分析方法研究了随机生成4组节理岩体的地下洞室的稳定性,得到了洞室节理围岩的裂隙扩展过程。同时通过对关键点位移的监测分析了锚杆的锚固效应。

Using DDARF （discontinuous deformation analysis for rock failure） method, the uniaxial and biaxial compression experiments of double-fractured rock mass are numerically investigated. Influences of fracture angle and lateral stress on behaviour of rock mass are studied and the corresponding stress-strain relationship curves are analyzed. Moreover, crack initiation stress and the peak strength of specimens are obtained. In the biaxial compression experiments of double-fractured rock mass, strength envelopes of 45~ fractured specimen under different lateral pressures are obtained. Using DDARF mothod, the axial load-displacement curves and crack propagation for four kinds of specimens with different anchor angles are obtained, which can simulate the anchorage effect on fractured rock. The simulation results and the previous splitting tests under similar conditions agree well with each other. The parameters obtained from biaxial compression experiment are used in a practical engineering example; and the differences of damage state between intact rock mass and fracture rock mass are analyzed after excavation of underground cavern by means of the equivalent mechanical character. At the last, the DDARF method is adopted to analyze the stability of an underground cavern with four groups of random joints; and then crack propagation process of jointed rock mass around the cavern are obtained. Besides, the effect of anchor on fractured rock mass are studied through monitoring the displacements of the key points.