压剪下煤矿岩石裂纹起裂角研究

Crack Initiation Angle Study for Coal Mine Rock under Compression Shear

在含裂隙煤矿岩石的压剪试验中,裂隙普遍为张开裂隙,对于张开裂隙的起裂及扩展,没有比较吻合的理论支撑;对压剪条件下确定不考虑张开度的张开裂隙进行分析,研究了张开裂隙尖端裂纹起裂角与预制裂隙倾角的关系。通过对含单条张开裂隙的试样开展室内试验和PFC数值模拟可知,煤矿岩石张开裂隙在单轴压缩条件下,翼裂纹首先出现;随着预制裂隙倾角的增大,裂纹起裂角不断减小,并趋近于70.5°;随着预制裂隙倾角的增大,尖端裂纹起裂角在不断减小;当预制裂隙倾角大于90°时,多数试样并不从预制裂隙处发生破坏。

In the compression shear test of coal mine rock with fractures,the fractures have been generally open fractures,and there has been no consistent theoretical support for the initiation and expansion of open fractures;the relationship between the crack initiation angle at the tip of the coal mine crack and the angle of the prefabricated crack has been studied.Through the indoor test and PFC numerical simulation of the sample with a single coal mine,it can be seen that the wing crack first appears under the condition of uniaxial compression;with the increase of the angle of pre cast crack,the crack initiation angle decreases and approaches 70.5°;the crack initiation angle of the tip crack decreases with the increase of the inclination angle for the prefabricated crack;when the inclination angle of the prefabricated crack is greater than 90°,most samples do not fail from the prefabricated crack.