次裂纹几何分布对裂纹岩体破坏机制影响研究

通过对含有裂纹的类岩石试件进行单轴压缩试验,研究次裂纹角度、长度以及岩桥尺寸对多裂纹岩体的破坏机制和裂纹扩展特征的影响规律。结果表明:次裂纹角度增加,初裂强度和峰值强度呈递增趋势,主、次裂纹闭合速度和宽度突增值减小,裂纹张开速度和剪切滑动变化值均增大。主、次裂纹之间岩桥贯通路径变短;次裂纹长度增加,初裂强度和峰值强度呈递减趋势,主、次裂纹宽度变化值和剪切滑动变化值均增加,次裂纹长度的增加降低了试件的完整度,岩桥贯通区域的椭圆形核体增大;岩桥尺寸增加,初裂强度呈递增趋势,峰值强度呈递减趋势,主、次裂纹宽度突增值和剪切应变增长值减小,裂纹张开速度和剪切应变突增值增加。分析总结了次裂纹几何分布对岩桥贯通的影响规律。

Study on the Influence of Crack Geometry Distribution on the Failure Mechanism of Crack Rock Mass

Through the uniaxial compression test of like-rock specimens containing cracks ,the influence of the secondary crack angle, the secondary crack length and the size of the rock bridge on the fracture mechanism of the multi-crack rock mass and the characteristics of crack propagation were studied. The results show that, with the increase of crack angle, initiation strength and peak strength show trend of increase. The closure speed of primary and secondary cracks and the value of sudden increment of crack width are decreased, and crack-opening velocity and shear slip variation value are increased. The connect path of the rock bridge between the primary and secondary cracks is shortened. With the increase of secondary crack length, initiation strength and peak strength show a trend of decrease. The width variation value and the shear slip variation value of primary and secondary cracks are increased, and the increase of crack length reduces the integrity of the specimens. The expansion of the elliptical nuclei in the rock bridge is increased. With the increase of rock bridge size, initiation strength shows a trend of increase and peak strength shows a trend of decline. The sudden increment of primary and secondary cracks width and shear strain growth value are decreased, and crack opening velocity and shear strain value are increased. The influence of the geometrical distribution of secondary crack on rock bridge coalescence is summarized.