基于CT动态扫描的冻土细观二元介质本构模型  

Binary-medium constitutive model for frozen soils based on CT dynamic scanning

作　　者：张革 刘恩龙 ZHANG Ge;LIU Enlong(Key Laboratory of Geological Hazards in Three Gorges Reservoir Area,Ministry of Education,China Three Gorges University,Yichang 443002,China;College of Civil Engineering&Architecture,China Three Gorges University,Yichang 443002,China;Northwest Institute of Eco-Environment and Resources,Chinese Academy of Sciences,Lanzhou 730000,China;College of Water Resources and Hydropower,Sichuan University,Chengdu 610065,China)

机构地区：[1]三峡库区地质灾害教育部重点实验室(三峡大学),湖北宜昌443002 [2]三峡大学土木与建筑学院,湖北宜昌443002 [3]中国科学院西北生态环境资源研究院,甘肃兰州730000 [4]四川大学水利水电学院,四川成都610041

出　　处：《岩土工程学报》2023年第9期1888-1896,共9页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(41771066)。

摘　　要：开展荷载作用下冻土的宏-细观力学特性试验研究,对揭示冻土细观力学特性和建立宏-细观力学性质之间的联系具有重要的意义。利用重新研制的可配合医用CT进行扫描的冻土三轴仪开展了不同温度、围压条件下的饱和冻土常规三轴压缩试验研究,其中在轴向加载过程中共对试样进行了8次CT扫描。通过对CT数平均值和应力应变曲线的分析发现:当应力应变曲线表现为应变硬化时,冻土试样CT数平均值随着轴向应变的增加而线性降低;当应力应变曲线表现为应变软化时,试样CT数平均值在软化阶段加速降低。结合动态扫描过程中试样CT数平均值的变化规律,提出利用试样CT数平均值对体积破损率进行表征,建立了饱和冻土的二元介质细观本构模型,并利用试验数据对建立的本构模型进行了验证,结果表明提出的本构模型能够很好的预测冻土在常规三轴应力路径下的应力应变行为。It is of great significance to carry out experimental researches on the macro-meso-mechanical properties of frozen soils to reveal the mechanism and the relationship between the meso-and the macro-meso-mechanical properties of frozen soils.The triaxial compression tests on the saturated frozen soils under four temperatures and four confining pressures are carried out by using the newly developed frozen soil triaxial instrument,which can cooperate with medical CT for dynamic scanning.A total of 8 CT dynamic scans are performed on the samples during the axial loading process.Through the statistical analysis of CT numbers and stress-strain curves,it is found that when the stress-strain curve is strain hardening,the average CT number of the frozen soil samples decreases linearly with the increase of the axial strain.When the stress-strain curve is strain softening,the average CT number of the frozen soil samples decreases rapidly at the softening stage.Based on the evolution laws of the average CT number of samples during the process of dynamic scanning,the breakage rate is characterized by the average CT number value,and the mesoscopic constitutive model for the saturated frozen soils is established,and the established constitutive model is verified through the test data.The results show that the proposed constitutive model can well predict the stress-strain behavior of frozen soils under the conventional triaxial stress path.

关 键 词：冻土 三轴压缩 CT动态扫描 细观力学特性 二元介质本构模型 

分 类 号：TU432[建筑科学—岩土工程]