非饱和原状土的弹塑性损伤本构模型
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摘要
自然界所存在的原状土具有一定的结构性,与室内重塑土在加载过程中所表现出的力学特性(如变形和强度)具有明显的差异.本文以复合体损伤理论为基础,建立了适用于非饱和原状土的弹塑性损伤本构模型,并给出了损伤变量λ的演化规律.其主要思想是把土材料看作由相对完整的土和相对破碎土两部分混合而成,二者的力学性能不同,且在受力过程中,相对完整的土逐渐转化为相对破碎的土,故分别采用弹性和弹塑性模型描述.该模型所采用的参数(除结构性参数β、α以外)均可以直接通过实验确定.结果表明,该模型能够较好描述非饱和原状土的应力-应变特性,尤其是应变软化现象,且所给出的扰动变量演化规律也能够较好描述土结构性退化规律.
The structured natural soils are widely distributed in nature,whose mechanical properties,such as deformation and strength characteristics,are completely different from the reconstituted soils,.This paper builds up an elasto-plastic damage constitutive model of unsaturated natural soils based on the damage theory of composite substance.The influence of soil structure characteristics on stress-strain behavior is considered in the model,and the evolution law of damage variableλis given.The main idea is to divide a soil body into two relatively intact soil body and relatively broken soil body,and the relatively intact soil body can be transformed into the relatively broken soil body during loading.In this paper,the deformation characteristics are described by elastic and elasto-plastic constitutive models,respectively.The parameters of model can be calibrated through experiments except the structural parameters β、α.By making comparisons of predictions with experimental data of unsaturated natural expansive soil and by conducting the parametric study,it is demonstrated that the new model captures the essential behaviors of the unsaturated natural soils,especially strain-softening behavior.
The structured natural soils are widely distributed in nature,whose mechanical properties,such as deformation and strength characteristics,are completely different from the reconstituted soils,.This paper builds up an elasto-plastic damage constitutive model of unsaturated natural soils based on the damage theory of composite substance.The influence of soil structure characteristics on stress-strain behavior is considered in the model,and the evolution law of damage variableλis given.The main idea is to divide a soil body into two relatively intact soil body and relatively broken soil body,and the relatively intact soil body can be transformed into the relatively broken soil body during loading.In this paper,the deformation characteristics are described by elastic and elasto-plastic constitutive models,respectively.The parameters of model can be calibrated through experiments except the structural parameters β、α.By making comparisons of predictions with experimental data of unsaturated natural expansive soil and by conducting the parametric study,it is demonstrated that the new model captures the essential behaviors of the unsaturated natural soils,especially strain-softening behavior.
引文
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[2]谢定义,齐吉琳.土结构性及其定量化参数研究的新途径[J].岩土工程学报,1999,21(6):651-656.XIE Dingyi,QI Jilin.Soil Structure Characteristics andNew Approach in Research on Its Quantitative Parameter[J].Chinese Journal of Geotechnical engineering,1999,21(6):651-656.(in Chinese)
[3]沈珠江.结构性黏土的弹塑性损伤模型[J].岩土工程学报,1993,15(3):21-28.SHEN Zhujiang.An Elasto-Plastic Damage Model forCemented Clays[J].Chinese Journal of Geotechnical engi-neering,1993,15(3):21-28.(in Chinese)
[4]熊传祥,龚晓南.一种改进的软土结构性弹塑性损伤模型[J].岩土力学,2006,27(3):395-398.XIONG Chuanxiang,GONG Xiaonan.An Updated E-lastoplastic Damage Model for Structural Soft-Clays[J].Rock and Soil Mechanics,2006,27(3):395-398.(inChinese)
[5]Liu M D,Carter J P.A Structured Cam Clay Model[J].Canadian Geotechnical Journal,2002,39:1313-1332.
[6]沈珠江,陈铁林.岩土破损力学:结构类型与荷载分担[J].岩土力学与工程学报,2004,23(13):2137-2142.SHEN Zhujiang,CHEN Tielin.Breakage Mechanics ofGeomaterial-Structure Types and Load Sharing[J].Chi-nese Journal of Rock Mechanics and Engineering,2004,23(13):2137-2142.(in Chinese)
[7]沈珠江,刘恩龙,陈铁林.岩土二元介质模型的一般应力应变关系[J].岩土工程学报,2005,27(5):489-494.SHEN Zhujiang,LIU Enlong,CHEN Tielin.GeneralizedStress-Strain Relationship of Binary Medium Model forGeological Materials[J].Chinese Journal of GeotechnicalEngineering,2005,27(5):489-494.(in Chinese)
[8]Asaoka A,Nakano M,Noda T,et al.Delayed Compres-sion/Consolidation of Naturally Clay Due to Degradation ofSoil Structure[J].Soils and Foundations:B,2000,40(3):75-85.
[9]沈珠江,邓刚.超固结黏土的二元介质模型[J].岩土力学,2003,24(4):495-499.SHEN Zhujiang,DENG Gang.Binary-Medium Modelfor Over-Consolidated Clays[J].Rock and Soil Mechan-ics,2003,24(4):495-499.(in Chinese)
[10]沈珠江,胡再强.黄土的二元介质模型[J].水利学报,2003(7):1-6.SHEN Zhujiang,HU Zaiqiang.Binary Medium Model forLoess[J].Journal of Hydraulic Engineering,2003(7):1-6.(in Chinese)
[11]陈铁林,沈珠江.岩样变形和破坏过程的二元介质模拟[J].水利水运工程学报,2004(1):1-5.CHEN Tielin,SHEN Zhujiang.Simulation of Rock De-formation and Failure by Binary Medium Model[J].Hy-dro-Science and Engineering,2004(1):1-5.(in Chi-nese)
[12]沈珠江.二元介质模型在黄土增湿变形分析中的应用[J].水利学报,2004(12):1-6.SHEN Zhujiang.Application of Binary Medium Model inDeformation Analysis of Loess During Wetting[J].Jour-nal of Hydraulic Engineering,2004(12):1-6.(in Chi-nese)
[13]Alonso E E,Gens A,Josa A.A Constitutive Model forPartially Saturated Soils[J].Geotechnique,1990,40(3):405-430.
[14]Sun D A,Cui H B,Hajime Matsuoka,et al.A Three-Dimensional Elastoplastic Model for Unsaturated Com-pacted Soils with Hydraulic Hysteresis[J].Soils andFoundations,2007,47(2):253-264.
[15]卢再华,陈正汉.非饱和原状膨胀土的弹塑性损伤本构模型研究[J].岩土工程学报,2003,25(4):422-426.LU Zaihua,CHEN Zhenghan.An Elastoplastic DamageConstitutive Model of Unsaturated Undisturbed Expansivesoil[J].Chinese Journal of Geotechnical Engineering,2003,25(4):422-426.(in Chinese)
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