考虑冰晶胶结特性的冰-冻土界面力学特性  

Mechanical properties of ice-frozen soil interface under cementation of ice crystals

作　　者：史盛 王冠夫 刘天赐 冯德成[3] 张锋[3] SHI Sheng;WANG Guanfu;LIU Tianci;FENG Decheng;ZHANG Feng(Research Center of Coastal and Urban Geotechnical Engineering,Zhejiang University,Hangzhou 310058,China;Center for Balance Architecture,Zhejiang University,Hangzhou 310012,China;School of Transportation Science and Engineering,Harbin Institute of Technology,Harbin 150090,China)

机构地区：[1]浙江大学滨海和城市岩土工程研究中心,杭州310058 [2]浙江大学平衡建筑研究中心,杭州310012 [3]哈尔滨工业大学交通科学与工程学院,哈尔滨150090

出　　处：《农业工程学报》2023年第14期114-124,共11页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家自然科学基金项目(41971076,42171128);黑龙江省重点研发项目(GA21A501)。

摘　　要：寒区多年冻土斜坡内部存在的下卧冰层对多年冻土斜坡稳定有着重要影响。为探究冰-冻土界面力学特性对斜坡稳定的影响,该研究以冰-冻土界面为研究对象,在低温环境(−3℃)下开展了不同冻土初始孔隙比和含水率下的冰-冻土界面及对应的冰-土颗粒界面直接剪切试验,建立了考虑冰晶胶结特性的冰-冻土界面非线性弹性损伤模型,结合试验结果对模型进行了验证,并分析了界面在剪切过程中切线刚度的变化规律。结果表明:冰-土颗粒界面的剪切应力表现为应变硬化特性,而冰-冻土界面的剪应力在峰值强度之后迅速下降,表现为应变软化特性。冰-冻土界面结构系数峰值点对应的剪切位移随着含水率的增大而增大,当冻土初始孔隙比为1.0、0.8和0.6,冻土初始含水率从14%增大至18%时剪切位移分别增大了32.7%、41.3%和52.1%。在−3℃下,冻土的初始含水率越大,则界面处的胶结冰越多,黏聚强度对界面的抗剪强度贡献也就越大。当结构系数达峰值点后,界面开始产生损伤,并随着剪切位移的增加进入加速损伤阶段。剪切过程中界面的切线刚度呈先增大后减小的趋势,在结构系数峰值点处为0,之后切线刚度随着剪切位移的增加逐渐减小。此外,界面的峰值切线刚度随着法向应力的增大而增大,当冻土初始孔隙比1.0、初始含水率为18%,法向应力从50 kPa增大至200 kPa时,则界面的峰值切线刚度增加了63.7%。在冰-冻土界面力学模型中考虑冰晶胶结特性更加合理,研究结果可为寒区斜坡稳定性分析提供参考。Water migration often occurs in the permafrost slopes during seasonal variations.The water can be accumulated in the vicinity of the freezing front,and then congealed into ice,due to the influence of gravitational and temperature fields.The underlying ice layer was gradually formed with the increase of ice thickness and area.The interface between the ice layer and the overlying frozen soil can play a crucial role in the stability of the permafrost slope.The mechanical behaviors of ice-frozen soil interface can provide the theoretical support for the stability assessment of permafrost slopes over the long term.This research aims to investigate the mechanical properties of the ice-frozen soil interface.A series of direct shear tests were conducted under the temperature of−3℃.The shear stresses of the ice-frozen soil interface and the ice-soil particles interface were investigated under different normal stresses,initial water contents,and initial void ratios of the frozen soil.The experimental results showed that the shear stress of the ice-soil particles interface exhibited the hardening behavior,and then increased with the decreasing void ratio of the frozen soil.Softening behavior was found in the shear stress of the ice-frozen soil interface,particularly under lower normal stresses.The shear stress also increased with the increasing initial water content of the frozen soil.The structural coefficient,damage variable,and structural strength of the ice-frozen soil interface were defined,according to the mechanical properties and the failure evolution of the ice-soil particles interface and ice-frozen soil interface.There was an increase in the shear displacement corresponding to the structural coefficient peak point of the icefrozen soil interface with the increase of initial water content.Furthermore,the initial water content of frozen soil increased from 14%to 18%,while the shear displacement increased by 32.7%,41.3%,and 52.1%,respectively,when the initial void ratios of frozen soil was 1.0,0.8,and 0.6.A nonl

关 键 词：剪应力 结构系数 非线性弹性模型 冰-冻土界面 损伤 切线刚度 低温直剪试验 

分 类 号：TU752[建筑科学—建筑技术科学]