甘肃北山地区花岗岩破坏过程能量聚集和耗散特征研究
Study on energy concentration and dissipation of Beishan granite in Gansu during failure process
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摘要: 对甘肃北山地区的花岗岩进行不同围压下三轴试验,通过轴向压力和横向变形联合控制加载过程,获得了不同围压下岩石全应力应变曲线,重点研究了岩石特征应力和不同阶段岩石能量变化特征。研究结果表明:随着围压的增加,特征应力线性增大,围压每增加1 MPa,启裂应力、损伤应力、峰值应力分别增加3.30 MPa、6.74 MPa、7.68 MPa;特征应力对应的总能量和弹性能均有较大幅度的增加,围压从2 MPa升高到30 MPa时,启裂应力、损伤应力和峰值应力对应的弹性能分别增加了5.2倍、5.8倍和5.1倍,启裂应力、损伤应力和峰值应力对应的总能量分别增加了4.9倍、5.7倍和4.7倍;各阶段耗散能增加量整体上随围压增大呈增加的趋势,且裂隙不稳定扩展阶段能量受围压影响更剧烈;定义峰值岩石储能系数,并分析储能系数对峰值岩石稳定状态的影响。Abstract: Servo test system was used to obtain stressstrain curves of Beishan granite under different confining pressure,and the loading process was jointly controlled by means of axial pressure and circumferential deformationVariation characteristics of energy and characteristic stress of Beishan granite were researchedCharacteristic stress are linear increase with confining pressure increasing,crack initiation stress,damage stress and peak strength increased 330 MPa,674 MPa,768 MPa respectively along with confining pressure increased 1 MPaTotal energy and elastic energy corresponding to characteristic stress are greatly increase with confining pressure increasingWhen confining pressure increased form 2 MPa to 30 MPa,elastic energy corresponding to initiation stress,damage stress and peak stress increased 52 times,58 times and 51 times respectively,corresponding total energy increased 49 times,57 times and 47 times respectivelyThe increment of dissipation energy increase with increasing of confining pressure,and energy at the crack unstable propagation stage was significant affected by confining pressureEnergy storage coefficient was defined to estimate rock stability around the peak strength,effect of stress state coefficient on energy storage was further analyzed