摘要
通过对取自长沙地铁深基坑的砂岩,在多功能岩石三轴测试系统上进行不同围压下的三轴循环加卸载试验,研究砂岩循环加卸载下的应力-应变关系,探讨围压、动应力幅值以及循环周次对砂岩的动弹性模量、动泊松比、阻尼比的影响。研究结果表明:循环加卸载增加了岩石损伤,应力-轴向应变曲线是一种内凹型且向应变增大方向迁移。应力-环向应变曲线更能体现疲劳损伤过程,不同动应力幅值下的剪缩临界点在同一条直线上。围压越大,相同动应力幅值下岩石应变量越大,动弹性模量越大,不同围压下的阻尼比的测试结果相差不大,而围压对动泊松比的影响不明显。随着动应力幅值的增加,弹性模量先减小后增大,动泊松比满足线性关系而动阻尼比满足幂函数关系。随着循环周次的增加,弹性模量满足线性关系且直线斜率很小,循环周次对动泊松比的影响很小。
The triaxial compression cyclic loading and unloading tests under different confining pressures were carried out on gray sandstone which was collected from subway deep foundation pit of Changsha.The stress-strain relationship of sandstone under cyclic loading was investigated.The effects of confining pressure,loading levels and cyclic loading numbers on dynamic elastic modulus,dynamic poison’s ratios and damping ratios were discussed.The experimental test results show that cyclic loading and unloading under different confining pressures can result in the damage of sandstone.The stress-axial strain curves are concave model and migrate to the direction of strain increasing.The stress-lateral strain curves can describe fatigue damage accurately.The critical point of shear shrinking of different loading levels composes a straight line.Both of the strain and the dynamic elastic modulus increase with the increase of the confining pressure under same loading level.Damping ratios appear not to be much different from confining pressure and so as to dynamic poison’s ratios.
作者
李启龙
贾朝军
傅鹤林
LI Qilong;JIA Zhaojun;FU Helin(Changsha Metro Group Co.Ltd.,Changsha 410007,China;School of Civil Engineering,Central South University,Changsha 410075,China)
出处
《铁道科学与工程学报》
CAS
CSCD
北大核心
2019年第10期2459-2466,共8页
Journal of Railway Science and Engineering
基金
国家自然科学基金资助项目(51578500,51978668)
中铁十四局项目(CSDT3-5-2017-0005)
关键词
岩石力学
循环加卸载
动弹性模量
动泊松比
阻尼比
围压
rock mechanics
cyclic loading
dynamic elastic modulus
dynamic poison’s ratio
damping ratio
confining pressure
