含交叉裂隙岩体力学性质数值模拟研究

岩体中裂隙的起裂、扩展及贯通是岩体破坏的重要原因,交叉裂隙是一种最为典型的基本裂隙网络组成单元,其在复杂应力场条件下的扩展贯通规律目前还缺乏深入的研究。本文采用RFPA2D对含交叉裂隙岩体破坏过程进行研究,探讨主裂纹与加载方向夹角变化、主裂纹与次裂纹的夹角变化对试件破坏模式及破坏力学性质的影响。模拟结果表明,主裂隙与加载方向垂直或者平行时,试件主要沿次裂隙发生剪切破坏;主裂隙与次裂隙夹角较小时,试件主要沿主裂隙发生剪切破坏。主裂隙角度一致时,大部分含交叉裂隙岩体的峰值强度低于含单一裂隙的岩体强度,主裂隙与加载方向夹角为45°时,岩体强度最低;岩体强度最高一般为主次裂隙夹角为0°或90°时;围压条件下,裂纹扩展方式较单轴压缩时更为复杂,很少出现由单条裂隙控制的破裂面,主要破裂面为主次裂隙首先贯通,且裂纹扩展时易产生较多的次生裂隙。数值模拟研究可以避免物理试验中的离散性,获得更为系统性的裂隙扩展贯通规律,对于解释岩体力学物理试验和解决工程问题都有重要的参考价值。

Numerical Simulation of Mechanical Properties of Rock Specimens with Cross-crack under Different Confining Pressure

Crack initiation,propagation and coalesce in rock masses are the important factors leading to rock failure.Cross-crack is one of the most typical and basic unit of the joint network.The principal of cross-crack under complicated stress conditions lacks the deep study.RFPA2D was used to study the failure process of rock specimens containing cross-cracks.Influence of the crack angles between primary crack and the direction of the maximal principal stress,the secondary crack on the failure models was also investigated.The numerical simulation shows that the specimens tend to be shear failure along the secondary crack when the angle between the primary crack and loading direction is almost vertical and horizontal.They tend to be shear failure along the primary crack when the angle between the primary crack and the loading direction is small.The peak strengths of the specimens which contained the cross-cracks are mostly smaller than those of single crack when the primary crack remains the same.The lowest strength appears when the angle between the primary crack and the loading direction is 45°.The highest strength of the rock specimens appears when the angle between the primary crack and secondary crack is 0° or 90°.It behaves more complex when the specimen is applied confining pressure,and few fracture surfaces are induced by a single crack.The main fracture surface is coalesced by the primary and secondary cracks.Many secondary crack appears in the process of the primary crack propagation.The study of numerical simulation can avoid the discreteness in physical tests and achieve more systematic rules of the crack propagation.The simulated results are contributed to explain the physical experiment of rock mechanics and understand problems in engineering.