被动围压下层理角度对页岩动态强度及耗能的影响

The influence of the bedding angle under passive confining pressure on the dynamic strength and energy consumption of shale

页岩在围压条件下的动力学特性,对页岩的高效致裂至关重要。采用分离式霍普金森压杆(SHPB)系统对页岩进行冲击试验,分析被动围压条件下页岩试件的强度特征、损伤特性和能量耗散规律。试验结果表明:在不同应变率下,页岩的损伤程度随冲击速度的提高显著提高,试件承载能力降低;在被动围压条件下,岩石材料的延性和抗破坏能力均得到提高,页岩从无围压条件下的脆性破坏向延性破坏过渡,页岩试件的屈服强度提高2.25~3.06倍,轴向应力峰值为无围压条件下的1.8~2.5倍;在被动围压条件下,页岩试件的能量耗散随平均应变率增大呈线性增长,在试验应变率范围内(ε=97~520)具有显著应变率相关性;页岩具有显著的横观各向同性特征,层理角度对页岩试件的强度特征、能量耗散和损伤特性均有显著影响。

In order to analyze the strength characteristics,damage characteristics and energy dissipation laws of the bedding shale specimens under passive confining pressure,the Hopkinson Pressure Bar(SHPB)device was used to perform different impact pressures and impact test(no confining pressure and passive confining pressure).The experimental research results show that under different impact pressure gradients,the damage degree of shale increases significantly with the increase of impact pressure gradient,and the bearing capacity of specimens decreases;the passive confining pressure condition significantly improves the anti-destructive ability of shale specimens.Transitioned from brittle failure to ductile failure under the condition of no confining pressure,the yield strength of the shale specimen is increased by 2.25~3.06 times,and the axial stress peak value is 1.8~2.5 times of that under the condition of no confining pressure;under the condition of passive confining pressure,the energy dissipation of shale specimens increases linearly with the increase of the average strain rate.It has a significant strain rate correlation within the strain rate range tested in this paper(ε=97~520);shale has a significant transverse view Isotropic characteristics and bedding angle have significant effects on the strength characteristics,energy dissipation and damage characteristics of shale specimens.