含2条偏置三维内裂纹试件单轴拉伸下裂纹扩展数值模拟

Numerical Simulation of Crack Propagation under Uniaxial Tension of Specimen with Two Offset Three-dimensional Internal Cracks

为探究不同岩桥角及不同裂纹倾角下的标准立方体试件在单轴拉伸作用下的裂纹扩展及裂纹尖端的应力强度因子的变化规律,利用Franc3d软件对不同方案的含两条偏置三维裂纹的试件进行了单轴拉伸数值模拟研究,同时以单轴拉伸下含单裂纹试件的试验结果作为验证对比,验证了数值模拟的合理性。结果表明,不同岩桥角与不同裂纹倾角下双裂纹试件裂纹之间呈现"相互吸引"与"相互排斥"作用;预制裂纹内侧尖端的翼裂纹扩展小于预制裂纹外侧尖端;相对Ⅰ型应力强度因子随着预制裂纹尖端距离的变化呈现先增大后减小再增大再减小的规律,相对Ⅱ型应力强度因子随着预制裂纹尖端距离的变化呈现先减小后增大再减小再增大的趋势;岩桥角越大,整体上的相对Ⅰ型应力强度因子越小,不同岩桥角的相对Ⅱ型应力强度因子几乎一致;预制裂纹的倾角越大,相对Ⅰ型应力强度因子越小,而相对Ⅱ型应力强度因子总体上越大。研究成果为进一步认识裂纹扩展特性奠定了基础。

In order to investigate the crack propagation and the variation of stress intensity factor at crack tip of standard cube specimen under uniaxial tension under different rock bridge angles and different crack dip angles, the uniaxial tensile numerical simulation of specimens with two biasing three dimensional cracks under uniaxial tension was carried out by using Franc3d software. And then the rationality of numerical simulation was verified by comparing the experimental results of the specimens with single crack under uniaxial tension. The results show that there is "mutual attraction" and "mutual repulsion" between the two crack specimens under different rock bridge angles at different crack inclination angles, and the wing crack propagation at the inner tip of the precast crack is smaller than that at the inner tip of the precast crack. Compared with mode I stress intensity factor, the stress intensity factor of prefabricated crack increases first and then decreases with the change of crack tip distance. The relative mode Ⅱ stress intensity factor decreases first and then decreases and then increases with the change of crack tip distance, and the larger the rock bridge angle, the smaller the relative mode I stress intensity factor on the whole. The relative mode Ⅱ stress intensity factor of different rock bridge angles is almost the same, and the larger the dip angle of the precast crack is, the smaller the relative mode I stress intensity factor is, and the larger the relative mode Ⅱ stress intensity factor is. The results of this study lay a foundation for further understanding of crack propagation characteristics.