考虑温度影响的非饱和土本构模型  

Constitutive model for unsaturated clays considering temperature effects

作　　者：姚仰平[1] 牛雷[1] 杨一帆[1] 崔文杰 胡贺祥[1] 

机构地区：[1]北京航空航天大学交通科学与工程学院,北京100191

出　　处：《岩土力学》2011年第10期2881-2888,共8页Rock and Soil Mechanics

基　　金：国家自然科学基金资助项目(No.50879001;No.11072016;No.10872016);国家重点基础研究发展规划资助项目(No.2007CB714103)

摘　　要：首先建立了反映温度对非饱和土前期固结压力影响的加载-升温(loading thermal,LT)屈服线,而后基于真强度概念并结合潜在强度的确定方法推导出不同温度下非饱和黏土临界状态应力比的理论计算公式;将LT屈服线与反映常温下吸力对土体前期固结压力影响的加载-湿陷(loading collapse,LC)屈服线结合,建立了加载-升温-湿陷(loading thermal collapse,LTC)屈服面,该屈服面综合考虑了温度和吸力对土前期固结压力的影响;最后在临界土力学框架内建立了一个考虑温度影响的正常固结非饱和土本构模型,并将其扩展到超固结非饱和土。与巴塞罗那模型相比,所提出的模型仅增加了一个参数来反映非饱和土的前期固结压力随温度升高而降低的特性。模型能够综合描述温度、吸力以及不同超固结程度对土应力、应变的影响,方便于数值计算和有限元分析。模型预测和试验分析表明,某一固定吸力下升温会使正常固结非饱和土强度提高;对于超固结非饱和土,升温或湿化均会破坏土体超固结,降低软化和剪胀的效果。The loading thermal（LT） yield curve is first introduced to consider the effects of temperature on the preconsolidation pressure change for unsaturated clays.Based on the concept of true strength and the calculation method of the potential failure stress ratio,the equation of the critical state stress ratio for unsaturated clays under different temperatures is deduced.The LT yield curve is then combined with the loading collapse（LC） yield curve which is used to consider the effects of suction on the preconsolidation pressure change for unsaturated clays,by which the loading thermal collapse（LTC） yield surface is presented.Therefore,the effects of both temperature and suction on the preconsolidation pressure change are considered by the LTC yield surface.After that,a constitutive model for normally consolidated unsaturated clays considering temperature effects is proposed based on the framework of the critical state soil mechanics;and it is extended to consider the properties of overconsolidated unsaturated clays.Compared with the Barcelona basic model,the proposed model requires only one additional parameter to consider the behavior of the decrease of preconsolidation pressure with an increase of temperature.The proposed model can describe the effects of temperature,suction and OCRs（overconsolidation ratios） on the stress-strain behavior for clays.Model predictions and test results show that heating will cause an increase of the strength for normally consolidated unsaturated clays at a given suction.The overconsolidation behavior decays or even disappears by either heating or wetting for overconsolidated unsaturated clays,consequently,the behavior of softening and shear dilatancy will be decayed.

关 键 词：非饱和土 吸力 温度 超固结 软化 湿化 三维化 

分 类 号：TU441[建筑科学—岩土工程]