单轴压缩条件下预制裂纹岩块破碎过程的数值模拟

Numerical simulation of the crushing process on rock with preexisted cracks under compression

应用FLAC3D软件对含预制裂纹砂浆块和完整砂浆块试样在单轴压缩点荷载作用下的破碎过程进行了数值模拟.结果表明:完整砂浆块的破碎过程首先出现一个应力集中区,形成密实核,然后形成中间裂纹、径向裂纹、侧向裂纹,这些裂纹迅速扩展,并衍生许多新的次生裂纹,沿着剪切或拉应力迹线贯通整个岩块;而含预制裂纹岩块的破碎则是在出现密实核后,随之在裂纹的两个端部出现应力集中,然后沿主载荷方向扩展,形成翼型裂纹,最后贯通整个试件;含预制裂纹试件和完整岩块的破碎应力-侵深曲线均出现跃进式特征,但裂纹试件裂尖局部的应力集中导致了翼型裂纹的产生并且沿主应力方向扩展,较早导致试件的破碎,其临界失稳荷载明显下降,预制裂纹对试件破碎效果的影响是显著的.

A numerical simulation by FLAC3D software approach on breaking process of pre-existing cracks in mortar block samples under compression of point load is carried out.The results show that the fracture process of complete mortar block first appears a stress concentration districts,forming close-grained nuclear,successively intermediate crack,radial crack,lateral crack appear,and these cracks expand quickly,and form many new secondary cracks,which will come along the shear or tensile stress tracing line through the whole rock;Contain prefabricated crack in the rock breaking is close-grained,then after appearing in crack nuclear two ends appear stress concentration,then along the main direction of expansion,forming load,finally transfixion crack airfoil whole specimens;Contain prefabricated crack rock specimens and complete the crushing stress——displacement curve all appear leaping broken characters,but crack specimens of the crack tip local stress concentration caused airfoil the fatigue and along the main stress direction of expansion,earlier cause specimen broken,the buckling critical load decreases obviously,prefabricated crack of specimen crushing effect is remarkable.