摘要
为探究人工地层冻结法实施过程中红黏土经历常温、冻结和冻融3种状态后的抗剪强度变化规律,采用低温MTS三轴试验系统,开展不同初始含水率、冻结温度和围压条件下重塑红黏土三轴剪切试验,探讨不同冻融状态下红黏土三轴剪切强度的特性,揭示不同条件下人工冻融全过程土体抗剪强度变化规律。结果表明:(1)冻结状态下红黏土应力应变曲线均呈应变硬化型,常温、冻融后随围压增大,应力应变曲线由应变软化型转为应变硬化型,较高围压(800 kPa)下表现为应变硬化;(2)冻结状态红黏土抗剪强度、黏聚力和内摩擦角都随含水率增加呈先增加后减小趋势,在含水率为30%时达到峰值;土体经历常温→冻结→冻融过程,冻结状态下抗剪强度平均提升10.5倍,冻融后抗剪强度低于常温状态;(3)冻结温度越低,冻结状态下红黏土的抗剪强度越大,冻融后红黏土黏聚力、内摩擦角及抗剪强度随冻结温度降低而减小。研究成果可为红黏土地层人工冻结法施工提供理论及技术参考。
In the pursuit of understanding the shear strength variations of red clay in three states,i.e.,normal,frozen,and freeze-thaw,during the implementation of the artificial permafrost method,a low-temperature MTS triaxial testing system is utilized.Triaxial shear experiments on remolded red clay are conducted under varying initial moisture levels,freezing temperatures,and confining pressures.The aim is to explore the triaxial shear strength characteristics of red clay in different freeze-thaw states and elucidate the variations in shear strength throughout the entire artificial freeze-thaw process under diverse conditions.The results show that:(1)In the frozen state,stress-strain curves of red clay consistently exhibit strain hardening.With increased confining pressure at normal temperature and post freeze-thaw cycles,stress-strain curves transition from strain softening to strain hardening,particularly evident under a high confining pressure of 800 kPa.(2)In the frozen state,the shear strength,cohesion,and internal friction angle of red clay exhibit an initial increase followed by a decrease with rising moisture content,reaching a peak at 30%.Throughout the process from normal temperature to freezing and then to freeze-thaw,the shear strength of red clay in the frozen state average increase is 10.5 times,while post freeze-thaw shear strength is lower than that at normal temperature.(3)Lower freezing temperatures correspond to higher shear strength in the frozen state of red clay.After freeze-thaw,cohesion,internal friction angle,and shear strength of red clay decrease with decreasing freezing temperatures.The study results can provide theoretical and technical insights for the construction of artificial permafrost in red clay formations.
作者
王升福
张祥荣
刘光炎
嵇晓雷
李向辉
Wang Shengfu;Zhang Xiangrong;Liu Guangyan;Ji Xiaolei;Li Xianghui(College of Civil and Architectural Engineering,East China University of Technology,Nanchang 330013,P.R.China;School of Architectural Engineering,Jiangsu Open University,Nanjing 210019,P.R.China;China Railway 16th Bureau Group Road and Bridge Engineering Co.,Ltd.,Beijing 101500,P.R.China)
出处
《地下空间与工程学报》
北大核心
2025年第3期871-881,共11页
Chinese Journal of Underground Space and Engineering
基金
国家自然科学基金(42167024,52168043,42061011)
江西省自然科学基金(20224BAB204068)
东华理工大学研究生创新项目(DHYC-202332)。
关键词
人工地层冻结
红黏土
应力应变曲线
三轴剪切强度
artificial ground freezing
red clay
stress-strain curves
triaxial shear strength
