含单个孔洞大理岩裂纹扩展细观试验和模拟

采用扫描电镜实时观测系统,对含单个孔洞大理岩进行了单轴压缩试验,实时观测了大理岩加载过程中裂纹的萌生、扩展、演化和贯通特征,获得了不同应力下大理岩裂纹扩展过程,试验结果表明:大理岩裂纹首先在孔洞周边的拉伸应力集中区域产生,随后沿加载方向或晶粒边界逐渐向试样端部或边界薄弱部位扩展.考虑岩石材料非均质性,采用岩石破裂过程分析系统,进一步对两种非均质岩样进行了数值模拟分析,模拟结果再现了两种晶粒大理岩试验过程中裂纹的扩展特征.试验和模拟得到的裂纹扩展规律吻合较好,非均质性(晶粒及其尺寸)对岩样中裂纹扩展特征具有较大的影响.

Investigations of Crack Expansion in Marble Having a Single Pre-existing Hole: Experiment and Simulations

Un-iaxial compression tests on marble were performed with an SEM real-time obser-vation system. Crack initiation, expansion and development around a pre-existing hole in the marble sample were photographed and analyzed under different loads. The results show that cracks initiate from the end of the part near a tension stress concentration field of the pre-exist-ing hole. The crack then expands toward the boundary softening area along the direction of loading or along the boundary of a crystal grain. Rock failure process analysis numerical simu-lations were carried out on rocks with two different heterogeneity indexes. Again, the expan-sion appears to involve two kinds of crystal grains. The experimental crack expansion relation-ship agrees with the simulated results. Effects of crystal and size heterogeneity on crack expan-sion are discussed. It is shown that the expansion path of cracks strongly depends upon hetero-geneity of the material.