摘要
人工冻结法是富水软岩地区地下工程的重要施工方法,探究冻结岩石强度特性的研究具有重要的理论研究价值和工程实际意义。白垩系饱和砂岩为研究对象,开展不同温度(+20℃,0℃,-10℃和-20℃),不同围压(0,2,4和6 MPa)条件下三轴压缩试验。研究结果表明冻结作用对饱和砂岩力学特性有着较大影响:(1)相同围压,温度由+20℃降到-20℃时,峰值强度提高2～4倍;(2)相同温度,围压由0 MPa升至6 MPa时,峰值强度提高1～3倍;(3)此外冻结状态下黏聚力可提高5倍,内摩擦角出现增大趋势。随后基于5种已有强度准则理论,以试验数据为参数计算各准则表达式并对比分析各准则对饱和砂岩冻结强度的预测效果,结果表明Rocker准则能够更为准确和方便的预测不同温度下饱和砂岩强度,并依此提出考虑温度效应的饱和砂岩Rocker强度准则,并验证了其具有良好的预测效果,上述结果将为低温环境下岩石力学特性研究及地下冻结工程设计施工提供有益的参考。
The artificial freezing method has been widely used in excavation of water-rich soft rock layers,and hence,understanding the mechanical properties of frozen rock is of great engineering significance.Taking saturated cretaceous sandstone as testing sample,triaxial compression tests with different confining pressures(0,2,4 and 6 MPa)were carried out at different temperatures(+20℃,0℃,-10℃and-20℃).The results demonstrate a strong negative correlation between the strength of saturated sandstone and the subzero temperature.Under the same confining pressure,the peak pressure increases by 2–4 times when the temperature reduces from+20℃to-20℃.At a constant freezing temperature,the peak strength increases by 1–3 times when the confining pressure increases from 0 MPa to 6 MPa.Both the cohesive force and the internal friction angle rise with decreasing the temperature,up to 5 times for the former.A strength forecasting model for frozen sandstone is proposed based on the comparison of prediction accuracy of five existing strength criterion theories according to the test results.The Rocker criterion is proven to be optimal and further modified taking into account the effect of the temperature on its parameters.The above results could provide a guidance for rock excavation both in cold regions and artificial frozen layers.
作者
杨更社
魏尧
申艳军
王磊
刘慧
董西好
李晓晋
YANG Gengshe;WEI Yao;SHEN Yanjun;WANG Lei;LIU Hui;DONG Xihao;LI Xiaojin(School of Architecture and Civil Engineering,Xi'an University of Science and Technology,Xi'an,Shaanxi 710054,China)
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2019年第4期683-694,共12页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金资助项目(51774231
41702334)
陕西省自然科学基础研究计划资助项目(2015JQ5186)~~
关键词
岩石力学
冻结砂岩
三轴压缩
变形破坏
强度预测
rock mechanics
frozen sandstone
triaxial compression
deformation and failure
strength forecasting
