高应变率单轴压缩下岩体裂隙扩展的细观位移模式

为了研究动态荷载作用下岩体裂隙扩展机制,通过细观颗粒平行黏结模型(PBM)的模拟,分析了高应变率单轴压缩条件下单裂隙岩样的损伤演化及细观位移场。高应变率大小对岩样最终破裂形态影响不大,但随应变率的增大,细观裂纹越多且局部化程度越强。随着裂隙倾角的增大,裂纹分叉交织越密,并在裂隙倾角≤45°和≥60°范围内分别具有相似的破裂形态。裂隙尖端翼裂纹是倾斜裂隙面相对滑移致使尖端撕裂的结果,高应变率下翼裂纹在峰后不再扩展。应变率越小,裂隙倾角越小,翼裂纹扩展的长度越长。定义了3类细观颗粒间的位移模式及其所形成的3类裂纹性质。将裂纹扩展概括为6种基本模式:翼裂纹+张拉、顺翼裂纹、反翼复合裂纹+张拉、顺翼复合裂纹+张拉、共面复合裂纹和倾斜复合裂纹,其中复合裂纹为拉剪裂纹或压剪裂纹。

Mesoscopic displacement modes of crack propagation of rock mass under uniaxial compression with high strain rate

In order to study crack propagation mechanism of rock mass under dynamic loading，the meso- damage evolution and displacement field of single fissure rock specimens under uniaxial compression with high strain rate were investigated using a parallel bond model (PBM) of meso- particle.The strain rate dependency of failure patterns of tested specimens relatively less than inclination of fissure.More meso- cracks and stronger damage localization are presented in the specimen with strain rate and fissure inclination increasing.And similar failure patterns are founded when fissure inclination ≤45° or ≥60°.Relative slide of the two sides of inclined fissure is prone to tear its tip and then generate wing cracks.The wing cracks usually stop propagation after peak strength.They are longer with smaller strain rate and inclination of fissure.Three displacement modes and its corresponding cracks properties between meso- particles are provided.Six basic propagation modes for cracks are summarized：wing cracks and extension，consequent wing cracks，composite cracks at reverse wing and extension，composite cracks at consequent wing and extension，coplanar composite cracks，and inclined composite cracks，where composite cracks are extensile- shear cracks or compressive- shear cracks.