不同渗透压作用下砂岩卸围压破坏过程中裂纹扩展行为研究
Crack propagation behavior in sandstone during unloading confining pressure under different seepage pressures
张登 1王在泉 1张黎明 1王肖珊2
作者信息
- 1. School of Civil Engineering,Qingdao University of Technology,Qingdao 266033,China
- 2. School of Science,Qingdao University of Technology,Qingdao 266033,China
- 折叠
摘要
地下工程开挖卸荷会导致岩体的水-力耦合作用增强,加速岩体内部裂隙的萌生和扩展,威胁工程安全.开展不同渗透压力作用下砂岩的常规三轴加荷和卸围压试验,明确砂岩裂纹应变扩展速率与应力路径和渗透压之间的内在联系.研究结果表明,围压增大,砂岩的特征应力增大,损伤应力和峰值应力对应的裂纹应变扩展速率减小,表明围压能够抑制裂纹应变的扩展.相反,随渗透压增加,砂岩的特征应力减小,而损伤应力和峰值应力对应的裂纹应变扩展速率会增大.表明渗透压会促进裂纹应变的扩展.围压相同,在渗透压和卸围压的共同作用下,砂岩峰值应力对应的裂纹应变扩展速率和脆性指数最大,其次是卸围压路径,加荷路径最小.通过量化围压和孔隙水压力对砂岩力学参数的影响权重,发现围压与峰值强度、轴向应变、环向应变、裂纹轴向应变和裂纹环向应变之间呈极显著相关.而孔隙水压力与裂纹轴向应变扩展速率、裂纹环向应变扩展速率也呈极显著相关.
Abstract
The unloading confining pressure tests were conducted on sandstone under the seepage pressure to reveal the relationships between the deformation characteristics and permeability and the stress paths and seepage pressure of the rock.The weights of influences of the confining pressure and seepage pressure on the damage of sandstone are quantified by symbolic statistics.Experimental results show that with the increasing confining pressure,the characteristic stress increases,and the growth rates of crack strain corresponding to the damage stress as well as the peak stress both decrease.However,with the increase of the seepage pressure,the characteristic stress decreases,the initial crack volumetric strain corresponding to the initiation stress reduces,the crack-growth volumetric strain corresponding to the damage stress increases and the growth rates of crack strain corresponding to the damage stress as well as the peak stress all increase.The permeability decreases slowly at first and then increases dramatically in the process of unloading confining pressure.Under the same confining pressure,the brittleness index and crack strain growth rates are the highest in the unloading test with seepage pressure,while they are moderate in the conventional unloading test,and the lowest in the loading test.The confining pressure is extremely correlated with the peak strength,axial strain,circumferential strain,crack circumferential strain corresponding to the peak strength.The seepage pressure is extremely correlated with growth rates of both crack axial strain and crack circumferential strain.
关键词
卸围压/水-力耦合/特征应力/裂纹应变扩展速率Key words
unloading confining pressure/coupled hydro-mechanical effect/characteristic stress/growth rate of crack strain引用本文复制引用
基金项目
National Natural Science Foundation of China(42272329)
National Natural Science Foundation of China(42272334)
Natural Science Foundation of Shandong Province,China(ZR2020ME099)
Natural Science Foundation of Shandong Province,China(ZR2020MD111)
出版年
2023
NETL
NSTL
维普
万方数据