考虑低温粒间吸力的饱和冻土UH模型  

UH model considering cryogenic intergranular suction for frozen saturated soil

作　　者：孔令明 张海兵 沈春廷 齐吉琳 KONG Lingming;ZHANG Haibing;SHEN Chunting;QI Jilin(School of Civil and Transportation Engineering,Beijing University of Civil Engineering and Architecture,Beijing 102616,China)

机构地区：[1]北京建筑大学土木与交通工程学院,北京102616

出　　处：《冰川冻土》2023年第3期1063-1079,共17页Journal of Glaciology and Geocryology

基　　金：国家自然科学基金项目(41902284,41972279,42172299);北京市自然科学基金项目(8204057);北京市教委一般项目(KM201910016015)资助。

摘　　要：冻土本构模型对于分析寒区岩土工程的安全和稳定性至关重要。低温吸力理论可以在物理层面解释温度对冻土力学特性产生影响的机理,且基于该理论所建立的冻土本构模型能实现融土和冻土本构关系的统一,所以近年来低温吸力理论受到越来越多的关注。本文首先通过分析饱和冻土中冰-水界面的表面张力作用,在低温吸力理论的基础上提出了低温粒间吸力的概念,并基于Clapeyron方程建立了低温粒间吸力与温度的关系式以及饱和冻土的有效应力公式。其次,针对多种类型的饱和冻土开展了温控侧限压缩试验和三轴剪切试验,发现低温粒间吸力对冻土力学特性的影响可以归结为其对冻土表观超固结性的影响,即冻土的表观超固结程度随低温粒间吸力的增大而增强。根据试验规律,建立了冻土表观前期固结压力和抗剪强度计算公式。最后,将以上所建立的冻土有效应力公式、前期固结压力公式和强度公式与超固结融土的统一硬化本构理论(即UH模型理论)结合,提出了一个新的冻土热力耦合弹塑性本构模型。使用该模型模拟冻土侧限压缩试验、单轴压缩试验和三轴剪切试验,发现其能合理描述冻土在不同温度和围压下的应力-应变关系,且计算结果与试验数据符合良好。The constitutive models of frozen soil are crucial for analyzing the safety and stability of geotechnical engineering in cold regions.The cryogenic suction theory can physically explain the mechanism of the influence of temperature on the mechanical properties of frozen soil,and the constitutive models based on this theory can unify the constitutive relationships of both thawed soil and frozen soil.Therefore,the cryogenic suction theory is being paid more and more attention recently.In this paper,firstly,by analyzing the surface tension on the icewater interface in saturated frozen soil,the concept of cryogenic intergranular suction was proposed based on the cryogenic suction theory.The function between cryogenic intergranular suction and temperature as well as the ef⁃fective stress formula of saturated frozen soil were established in light of the Clapeyron equation.Secondly,some temperature-controlled confined compression tests and triaxial compression tests were conducted on vari⁃ous frozen saturated soils,obtaining that the effect of cryogenic intergranular suction on the mechanical proper⁃ties of frozen soil can be attributed to its effect on the apparent overconsolidation of frozen soil,i.e.,the degree of apparent overconsolidation increases with the increase of cryogenic intergranular suction.According to the ex⁃perimental results,the formulae for the apparent pre-consolidation pressure and shear strength of frozen soil were established.Finally,the above established formulae of frozen soil,including the effective stress formula,preconsolidation pressure formula,and shear strength formula were combined with the unified hardening constitu⁃tive model(UH model)of overconsolidated thawed soil,and a novel thermo-mechanical elastoplastic constitu⁃tive model for frozen soil was proposed.The model was then used to simulate the confined,triaxial and uniaxial compression tests on frozen soil,and found to be able to describe the stress-strain relationship of frozen soil un⁃der different temperatures and c

关 键 词：冻土 本构模型 低温吸力 超固结 侧限压缩 

分 类 号：TU43[建筑科学—岩土工程] P642.14[建筑科学—土工工程]