基于离散元法三裂纹岩石裂纹扩展特征的试验与数值研究

Experimental and numerical study of crack propagation characteristics of tri-cracked rocks based on distinct element method

为研究三裂纹岩石的静力学破坏特征,采用离散元数值模拟软件PFC2D和模型试验方法,分析三裂纹岩石的峰值应力、应力—应变曲线及裂纹扩展特性,验证离散元数值模拟方法的可行性。通过改变岩石的水平围压和裂纹长度,分析单轴压缩载荷作用下三裂纹岩石的力学响应机制。研究结果表明:中间横向裂纹对裂纹岩石的峰值应力影响较大,中间竖向裂纹对裂纹岩石的峰值应力影响较小;加载过程中裂纹尖端最先出现应力集中现象,最后形成2条约70°的主裂纹贯通3条预制裂纹;随着围压的增大,三裂纹岩石的峰值应力先增大后减小;随着裂纹长度的增加,三裂纹岩石的峰值应力不断减小。

In order to study the static damage characteristics of the tri-cracked rock,the distinct element numerical simulation software PFC 2D and model tests were used to analyze the peak strength,stress-strain curve and crack propagation characteristics of the tri-cracked rock,and to verify the feasibility of the distinct element numerical simulation method.By varying the horizontal confining pressure and crack length of rock,the mechanical response mechanism of the tri-cracked rock under uniaxial compressive loading was analyzed.The results show that the intermediate transverse crack has a greater effect on the peak stress of the cracked rock,and the intermediate vertical crack has a less effect on the peak stress of the cracked rock.During the loading process,stress concentration occurs at the crack tip primarily and ultimately two main cracks of about 70°are formed through three prefabricated cracks.With the increase of confining pressure,the peak stress of the tri-cracked rock increases first and then decreases.