Abstract

The laboratory tests and Particle Flow Code numerical simulation of triaxial compression are conducted to analyze fractal dimensions of fracture surface, strength properties, energy dissipation, damage laws and crack evolution. Under low confining pressure, the fracture surface of the brittle specimen is rough and the angle relative to the maximum principal stress is small. The specimen eventually exhibits local tensile-shear failure mode. With the increase of confining pressure, the strength of the specimen increases and yield platform for the stress–strain curve is more obvious. The main fracture surface becomes increasingly flatter and the fracture angle increases with the increase of confining pressure. The specimen exhibits a shear failure mode macroscopically. With the increase of confining pressure, the trend of transgranular shear failure becomes obvious and the micro-fracture surface has a smaller fractal dimension. In the triaxial compression test, energy storage, dissipation and release occur. When the storage limit is reached, the internal elastic strain energy releases sharply and the damage variable increases rapidly. As the confining pressure increases, the number of tensile and shear cracks is accumulated in an ‘S’ shape. Meanwhile, the proportion of shear cracks increases gradually.

摘要

对三轴压缩进行室内试验和Particle Flow Code数值模拟，分析断口的分形维数、强度特性、能量耗散、损伤规律和裂纹演化。在低围压下，脆性试样断口粗糙，相对于最大主应力的夹角较小。试样最终表现出局部拉伸剪切破坏模式。随着围压的增加，试件的强度增加，应力-应变曲线的屈服平台更加明显。随着围压的增加，主断裂面越来越平坦，断裂角度也越来越大。试样在宏观上表现出剪切破坏模式。随着围压的增加，穿晶剪切破坏趋势明显，微裂缝面分形维数变小。在三轴压缩试验中，会发生能量的储存、耗散和释放。当达到储存极限时，内部弹性应变能急剧释放，损伤变量迅速增加。随着围压的增加，拉伸裂缝和剪切裂缝的数量以“S”形累积。同时，剪切裂纹的比例逐渐增加。拉伸和剪切裂纹的数量以“S”形累积。同时，剪切裂纹的比例逐渐增加。拉伸和剪切裂纹的数量以“S”形累积。同时，剪切裂纹的比例逐渐增加。