基于含圆孔砂岩试样三轴动载压缩试验的分区破裂化现象

Zonal disintegration phenomenon based on triaxial dynamic load test of hollow cylindrical sandstone specimens

在深部巷道开挖过程中出现的围岩分区破裂现象引起了广泛关注,然而以岩石试样为研究对象的室内试验对分区破裂现象的研究较少。本文采用霍普金森压杆装置对不同围压下的含圆孔砂岩试样进行三轴压缩试验,试样在冲击破坏后均出现分区破裂现象。对试样进行弹塑性分析,发现在弹塑性边界处存在的最大拉伸应变是径向环形裂纹和分区破裂形成的主要原因。在试样塑性区的圆孔附近存在较大的拉伸应变,导致圆孔附近岩石容易发生剥落;在试样的弹性区,环向应变随着半径的增大而从压应变转换为拉应变,导致试样周边容易出现拉伸裂纹。采用ABAQUS对试验过程进行模拟,模拟结果与试验结果以及理论分析基本一致。相比理论分析,模拟得出的结果更为直观地解释了圆孔附近岩石的剥落现象。

In the process of deep roadway excavation,the zonal disintegration phenomenon of surrounding rocks has attracted a lot of attention from rock mechanics.There are relatively few studies on zonal disintegration of rock specimens in laboratory experiments.In this paper,a split Hopkinson pressure bar device was used to perform compression tests on hollow cylindrical sandstone specimens under different confining pressures.The failure specimen shows zonal disintegration.According to the theoretical analysis of elastic-plastic mechanics,it is found that there is a maximum tensile strain at the elastic-plastic boundary,which leads to annular cracks in the radial direction and the formation of zonal fractures.In the plastic zone of the specimen,there is a large tensile strain near the hole.As a result,it is prone to spalling near the hole.In the elastic zone of the specimen,as the radius increases,the hoop strain is converted from compressive strain to tensile strain,resulting in tensile cracks on the outside of the specimen.The phenomenon was also simulated using ABAQUS.The simulation results are basically consistent with the experiments and can intuitively explain the spalling around the hole and the damage to the specimen.