三场耦合作用下黏土岩损伤变形特性及本构模型
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摘要
深部地下围岩常常处于温度场、渗流场、应力场等多场耦合作用,研究黏土岩在温度-渗流-应力场耦合作用下的变形损伤演化过程尤为重要。从试验和理论模型2个方面对黏土岩开展了温度-渗流-应力三场耦合特性研究,结果表明:高温会造成黏土岩内部结构发生质的劣化,黏土岩的温度越高,其峰值强度越小,而应变变形量越大;渗透系数随变形总体呈先减后增的趋势,并在峰后阶段略有降低,分别与体变压缩硬化、剪胀损伤、软化剪胀3阶段相对应,体积变形的转折拐点即为渗透率加速增大的临界点;黏土岩的渗透率随温度升高呈先减小后增大的趋势,当温度<50℃时,渗透率随温度升高而减小,当温度>50℃后,随温度升高而增大;温度越高,黏土岩的"实损伤"发展越快。基于试验结果,建立了温度-渗流-应力三场耦合作用下的损伤本构模型,该模型能较好地模拟黏土岩三场耦合作用下的损伤变形演化过程。
Deep underground rock is often subjected to the coupled actions of temperature field, seepage field and stress field. In this paper, the thermal-hydro-mechanical coupling characteristics of clay rock are studied via experimental and theoretical approaches. First of all, triaxial compression tests were conducted at different temperatures to reveal the relationship among temperature, deformation, and permeability as follows: high temperature deteriorated the internal structure of clay rock in a qualitative sense by degrading peak strength and raising strain deformation; permeability coefficient firstly declined and then increased along with deformation, and decreased slightly in post-peak stage, respectively corresponding to three stages(volumetric strain compression hardening stage, dilatancy hardening stage, and dilatancy softening stage), with the turning point of volumetric deformation implying the acceleration of permeability; under 50 ℃, the permeability of clay rock reduced with the climbing of temperature, while increased when above 50 ℃, with the real damage developing rapidly. On the basis of such experimental results, a constitutive damage model of clay rock under thermal-hydro-mechanical coupling effect was established, and was verified by experimental results.
Deep underground rock is often subjected to the coupled actions of temperature field, seepage field and stress field. In this paper, the thermal-hydro-mechanical coupling characteristics of clay rock are studied via experimental and theoretical approaches. First of all, triaxial compression tests were conducted at different temperatures to reveal the relationship among temperature, deformation, and permeability as follows: high temperature deteriorated the internal structure of clay rock in a qualitative sense by degrading peak strength and raising strain deformation; permeability coefficient firstly declined and then increased along with deformation, and decreased slightly in post-peak stage, respectively corresponding to three stages(volumetric strain compression hardening stage, dilatancy hardening stage, and dilatancy softening stage), with the turning point of volumetric deformation implying the acceleration of permeability; under 50 ℃, the permeability of clay rock reduced with the climbing of temperature, while increased when above 50 ℃, with the real damage developing rapidly. On the basis of such experimental results, a constitutive damage model of clay rock under thermal-hydro-mechanical coupling effect was established, and was verified by experimental results.
引文
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[2] CHEN L,LIU Y M,WANG J,et al.Investigation of the Thermal-hydro-mechanical (THM) Behavior of GMZ Bentonite in the China-Mock-up Test[J].Engineering Geology,2014,172:57-68.
[3] 王长轩,刘晓东,刘平辉.高放废物地质处置黏土岩处置库围岩研究现状[J].世界核地质科学,2008,25(2):98-103.
[4] SAVAGE D.The Scientific and Regulatory Basis for the Geological Disposal of Radioactive Waste[M].Chichester:John Wiley and Sons,1995.
[5] 薛强,赵颖,刘磊,等.垃圾填埋场灾变过程的温度-渗流-应力-化学耦合效应研究[J].岩石力学与工程学报,2011,30(10):1970-1988.
[6] ABUEL-NAGA H M,BERGADO D T,CHAIPRAKAIKEOW S.Innovative Thermal Technique for Enhancing the Performance of Prefabricated Vertical Drain during the Preloading Process[J].Geotextiles and Geomembranes,2006,24(6):359-370.
[7] 陈卫忠,龚哲,于洪丹,等.黏土岩温度-渗流-应力耦合特性试验与本构模型研究进展[J].岩土力学,2015,36(5):1217-1238.
[8] 龚哲.Boom clay温度-渗流-应力耦合长期力学特性研究[D].北京:中国科学院大学,2015.
[9] GB/T 50266—99,工程岩体试验方法标准[S].北京:中国计划出版社,1999.
[10] 梁海安.不同温度下塔木素黏土岩力学强度特性研究[C]∥第5届废物地下处置学术研讨会论文集.中国岩石力学与工程学会,2014:6.
[11] 范秋雁,阳克青,王渭明.泥质软岩蠕变机制研究[J].岩石力学与工程学报,2010,29(8):1555-1561.
[12] 杨永杰,宋扬,陈绍杰.煤岩全应力-应变过程渗透性特征试验研究[J].岩土力学,2007,28(2):38l-385.
[13] 王军.损伤力学的理论与应用[M].北京:科学出版社,1997:2-3.
[14] ASAOKA A,NAKANO M,NODA T.Superloading Yield Surface Concept for Highly Structured Soil Behavior[J].Soils and Foundations,2000,40(2):99-110.
[15] 贾善坡.Boom Clay泥岩渗流-应力-损伤耦合流变模型、参数反演与工程应用[J].岩石力学与工程学报,2009,28(12):2594.