岩石试件中非平行双裂纹扩展贯通规律的数值模拟研究

含裂纹岩石试件的裂纹扩展贯通规律的研究是岩石力学与岩土工程重要的研究方向之一。本文采用颗粒离散元数值模拟软件PFC2D,对含有两条非平行裂纹的类岩石材料试件的单轴压缩试验进行数值模拟。通过统计裂纹模式,发现了两种不同于两条平行裂纹间结合的模式,这两种结合模式中的水平裂纹多与原点倾斜裂纹在水平方向有重合。由试件的力学响应可知,当水平裂纹位于相同高度时,水平裂纹在原点裂纹正上方或正下方的试件峰值应力最大,且中心两侧峰值应力呈近似对称分布;裂纹的贯通多发生在试件的轴向应力达到其峰值的前后,且伴随试件应力应变曲线从塑性强化阶段到试件的破坏,微裂纹的数目呈现规律性的变化,裂纹的贯通和微裂纹数目变化都能在一定程度上预测或反映试件的破坏。室内试验验证了数值模拟中不同扩展模式的存在,说明数值模拟研究的可行性。

Numerical simulation of non-parallel double crack propagation and coalescence in rock specimen

The study of crack propagation through the cracked rock specimen is an important research direction of rock mechanics and geotechnical engineering.In this paper,a single axis compression test of a class of rock samples with two non-parallel cracks is carried out by using the numerical simulation software PFC2D.By means of statistical crack model,two kinds of coalescence modes are found,which are different from the modes of two parallel cracks.The two crack coalescences occurred when the origin inclined crack and another crack have the overlap part in the horizontal direction.From the mechanical response of the specimen,the peak stress of the specimen is the largest when the horizontal cracks are in the same level and the horizontal cracks located in below or above of the origin inclined crack,and the peak stress of the two sides are approximately symmetric.The coalescence of cracks occurred in the stress has reached or not reached its peak value,and the number of the micro-cracks changes regularly when the stress and strain curves of the specimens are from the plastic to the failure of the specimens.The coalescences of cracks and the number of micro-cracks can predict or reflect the failure of the specimen to a certain extent.By the laboratory tests,we found the same coalescence modes that exist in the numerical simulation and it demonstrates the feasibility of numerical simulation.