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大量的细观试验研究发现,岩石破坏主要是裂纹沿着岩石晶体颗粒边界的扩展造成的(沿晶断裂),裂纹沿弯折晶界的扩展则构成了不同材料边界上翼裂纹的扩展。基于以上细观试验结果,建立奇异单元的有限元模型,通过对节点位移的数值外插法,得到了岩石材料沿晶断裂翼裂纹应力强度因子,并研究了晶粒几何特征和材料非均质性(Dundurs参数)对裂纹扩展的影响。研究表明:在均质情况下,晶粒的几何形状在接近正六边形的情况下最适合裂纹扩展。随着非均质性的增强,各主翼裂纹比和晶粒几何角度所对应的KI值都要较均质模型的结果更高,最大的KI所对应的晶粒的内角角度也有所增加。综合所有计算结果可以看出,岩石中晶粒的非均质程度越高,越利于岩石破裂。
A large number of mesoscale experimental studies have found that the rock failure is mainly caused by the propagation of cracks along the grain boundaries of the rock (intergranular fracture), and the expansion of the crack along the bend grain boundaries constitutes an extension of the wing cracks on different material boundaries. Based on the results of the above meso-experiments, the finite element model of singular elements was established. The stress intensity factor of crack along the grain of rock material was obtained by numerical extrapolation of node displacement. The effects of grain geometry and material heterogeneity Effect of Dundurs Parameters on Crack Propagation. The results show that under homogeneous conditions, the grain geometry is best suited for crack propagation near a regular hexagon. With the enhancement of heterogeneity, the KI values corresponding to the crack ratio and grain geometry angle of the main wing are higher than that of the homogeneous model, and the angle angle of the grain corresponding to the largest KI also increases. Based on all the calculations, it can be seen that the higher the degree of heterogeneity of the grains in the rock, the better the rock is broken.