中主应力系数影响下的冻结砂土损伤本构模型  

Damaged constitutive model of frozen sand under the influence of intermediate principal stress

作　　者：麻世垄 姚兆明 刘爽[2] 潘旋 MA Shilong;YAO Zhaoming;LIU Shuang;PAN Xuan(State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines,Anhui University of Science and Technology,Huainan 232001,China;School of Civil Engineering and Architecture,Anhui University of Science and Technology,Huainan 232001,China)

机构地区：[1]煤矿深井建设技术国家工程实验室,安徽淮南232001 [2]安徽理工大学土木建筑学院,安徽淮南232001

出　　处：《煤田地质与勘探》2020年第5期130-136,共7页Coal Geology & Exploration

基　　金：地下工程福建省高校重点实验室开放课题基金项目(KF-T18014)。

摘　　要：人工冻结法是饱水砂层开挖过程中常用的止水和临时支护方法,通过冻土损伤特性研究为冻土力学特性和冻结体稳定性分析奠定基础。为研究冻结砂土的损伤力学特性,在–5℃下进行了不同中主应力系数的冻结砂土三维室内试验。从冻土微元破坏服从Weibull随机分布的特点出发,将Drucker-Prager强度准则作为冻土微元统计分布变量,利用应变等价性假说,建立了三维应力状态下冻结砂土损伤本构模型;在此基础上,讨论模型参数F0与m和中主应力系数的关系,对模型参数进行合理修正,建立中主应力系数影响下的冻结砂土损伤本构模型,并与试验结果进行对比。分析结果表明:参数F0和m随着中主应力系数的增大呈现先减小后增大的趋势;参数F0反映了冻结砂土的强度特性,参数m代表了冻结砂土的延性及脆性特征,考虑中主应力系数影响的冻结砂土损伤本构模型能很好地模拟冻结砂土应力–应变全过程曲线。研究成果为人工冻结法工程设计提供一定的理论依据。Artificial freezing is a commonly used method for stopping water and providing temporary support during the excavation of saturated sand.This study on the damage characteristics of frozen soil lays the foundation for the analysis of the mechanical properties of frozen soil and the stability of frozen bodies.In order to study the damage mechanical properties of frozen sand,three-dimensional laboratory tests on frozen sand with different intermediate principal stress coefficients were carried out at–5℃.Based on the Weibull random distribution of micro element failure of frozen soil,the Drucker-Prager strength criterion was invoked as the statistical distribution variable,and the strain equivalence hypothesis was used to establish the damage constitutive model of frozen sand under three-dimensional stress state.On this basis,the model parameters F0 and m are discussed the damage constitutive model of frozen sand under the influence of medium principal stress coefficient is established by modifying the model parameters reasonably and comparing with the test results.The results show that the parameters F0 and m decrease first and then increase along with the increase of the intermediate principal stress coefficient;the parameter F0 reflects the strength characteristics of frozen sand,and the parameter m represents the ductility and brittleness of frozen sand.The damage constitutive model of frozen sand considering the influence of medium principal stress coefficient can effectively simulate the whole stress-strain curve of frozen sand.The research results provide a theoretical basis for the engineering design of an artificial freezing method.

关 键 词：三轴应力状态 中主应力系数 DRUCKER-PRAGER准则 WEIBULL分布 损伤本构模型 

分 类 号：TU443[建筑科学—岩土工程]