统一考虑加载变形与流变的粗粒土弹塑性本构模型及应用
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摘要
实测资料表明,现行粗粒土本构模型明显低估高度200m以上特高土石坝的沉降量,主要原因之一是现行本构模型普遍割裂加载变形与流变,计算时忽略施工过程中坝料产生的流变。在总结分析典型粗颗粒土石料流变特性的基础上,以应力、应变和时间为基本变量,提出了一个可以统一模拟粗粒土加载变形、流变、应力松弛等性质的弹塑性本构模型。模型假定加载塑性变形和流变可同时发生,应力和时间变化均会引起屈服面扩张,从而产生塑性变形,但两者服从不同的塑性流动准则。运用某特高心墙堆石坝坝壳堆石料和砾石土心墙料的试验结果对模型的合理性进行了验证,并对该大坝填筑施工过程进行了模拟。计算结果表明,忽略坝料施工期流变可使大坝竣工期沉降量低估10%以上。因此,采用统一模拟粗粒土加载变形与流变的本构模型可有效提高特高土石坝变形的预测精度。
The field observations show that the existing widely-used constitutive models tend to underestimate the settlement of dams higher than 200 m. One of the main reasons is the separation of load-induced deformation and creep in such models and the neglecting of creep during construction in numerical simulations. In this study, a constitutive model, taking the stress, strain and time as the basic variables, is proposed in the light of experimental observations to model the loading deformation, creep and stress relaxation in a unified manner. A basic assumption used is the simultaneous occurrence of the load-induced plastic strains and creep strains. Both the change of stresses and the accumulation of time can result in expansion of the yield surface and thus produce plastic strains to obey, however, different flow rules. The model is used to reproduce the experimental results of a rockfill material and a gravelly soil used in an extremely high rockfill dam, and it is further used to study the deformation behavior of the dam. The numerical results show that neglecting the creep during construction may underestimate the settlement by more than 10%. Therefore, for the extremely high rockfill dams, it is necessary to use the unified models to consider the creep and loading behavior for rockfill materials so as to increase the precision of predictions.
The field observations show that the existing widely-used constitutive models tend to underestimate the settlement of dams higher than 200 m. One of the main reasons is the separation of load-induced deformation and creep in such models and the neglecting of creep during construction in numerical simulations. In this study, a constitutive model, taking the stress, strain and time as the basic variables, is proposed in the light of experimental observations to model the loading deformation, creep and stress relaxation in a unified manner. A basic assumption used is the simultaneous occurrence of the load-induced plastic strains and creep strains. Both the change of stresses and the accumulation of time can result in expansion of the yield surface and thus produce plastic strains to obey, however, different flow rules. The model is used to reproduce the experimental results of a rockfill material and a gravelly soil used in an extremely high rockfill dam, and it is further used to study the deformation behavior of the dam. The numerical results show that neglecting the creep during construction may underestimate the settlement by more than 10%. Therefore, for the extremely high rockfill dams, it is necessary to use the unified models to consider the creep and loading behavior for rockfill materials so as to increase the precision of predictions.
引文
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[15]KIM M K,LADE P V.Single hardening constitutive model for frictional materials:I plastic potential function[J].Computers and Geotechnics,1988,5(4):307-324.
[16]COLLINS I F,KELLY P A.A thermomechanical analysis of a family of soil models[J].Géotechnique,2002,52(7):507-518.
[17]沈珠江.理论土力学[M].北京:中国水利水电出版社,2000.(SHEN Zhu-jiang.Theoretical soil mechanics[M].Beijing:China Waterpower Press,2005.(in Chinese))
[18]李国英,米占宽,傅华,等.混凝土面板堆石坝堆石料流变特性试验研究[J].岩土力学,2004,25(11):1712-1716.(LI Guo-ying,MI Zhan-kuan,FU Hua,et al.Experimental studies on rheological behaviors for rockfills in concrete faced rockfill dam[J].Rock and Soil Mechanics,2004,25(11):1712-1716.(in Chinese))
[2]马洪琪.300 m级面板堆石坝适应性及对策研究[J].中国工程科学,2011,13(12):4-8.(MA Hong-qi.300 m grade concrete faced rockfill dam adaptability and countermeasures[J].China Engineering Sciences,2011,13(12):4-8.(in Chinese))
[3]陈生水.土石坝试验新技术研究与应用[J].岩土工程学报,2015,37(1):1-28.(CHEN Sheng-shui.Experimental techniques for earth and rockfill dams and their applications[J].Chinese Journal of Geotechnical Engineering,2015,37(1):1-28.(in Chinese))
[4]杨启贵,刘宁,孙役,等.水布垭面板堆石坝筑坝技术[M].北京:中国水利水电出版社,2010.(YANG Qi-gui,LIU Ning,SUN Yi,et al.Construction technologies in the Shuibuya concrete face rockfill dam[M].Beijing:China Water Power Press,2010.(in Chinese))
[5]陈生水,阎志坤,傅中志,等.特高面板砂砾石坝结构安全性论证[J].岩土工程学报,2017,39(11):1949-1958.(CHEN Sheng-shui,YAN Zhi-kun,FU Zhong-zhi,et al.Evaluation of the safety performance of extremely high slab faced gravel dam[J].Chinese Journal of Geotechnical Engineering,2017,39(11):1949-1958.(in Chinese))
[6]马刚,周伟,常晓林,等.堆石体三轴剪切试验的三维细观数值模拟[J].岩土工程学报,2011,33(5):746-753.(MA Gang,ZHOU Wei,CHANG Xiao-lin,et al.3Dmesoscopic numerical simulation of triaxial shear tests for rockfill[J].Chinese Journal of Geotechnical Engineering,2011,33(5):746-753.(in Chinese))
[7]花俊杰,周伟,常晓林,等.堆石体应力变形的尺寸效应研究[J].岩石力学与工程学报,2010,29(2):328-335.(HUA Jun-jie,ZHOU Wei,CHANG Xiao-lin,et al.Study of scale effect on stress and deformation of rockfill[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(2):328-335.(in Chinese))
[8]FU Z Z,CHEN S S,SHI B X.Large-scale triaxial experiments on the creep behavior of a saturated rockfill material[J].Journal of Geotechnical and Geoenvironmental Engineering,2018,144(7):04018039.
[9]傅中志,陈生水,张意江,等.堆石料加载与流变过程中的塑性应变方向研究[J].岩土工程学报,2018,40(8):1405-1414.(FU Zhong-zhi,CHEN Sheng-shui,ZHANG Yi-jiang,et al.Plastic strain directions of rockfill materials during loading and creeping[J].Chinese Journal of Geotechnical Engineering,2018,40(8):1405-1414.(in Chinese))
[10]ZHANG B Y,CHEN T,PENG C,et al.Experimental study on loading-creep coupling effect in rockfill material[J].International Journal of Geomechanics,2017,17(9):0000938.
[11]LADE P V,LIU C T.Experimental study of drained creep behavior of sand[J].Journal of Engineering Mechanics,1998,124(8):912-920.
[12]KARIMPOUR H,LADE P V.Creep behavior in Virginia Beach sand[J].Canadian Geotechnical Journal,2013,50(11):1159-1178.
[13]FU Z Z,WANG T B,CHEN S S.Field settlement observations made on four concrete face rockfill dams[C]//Proc 4th Int Conf on Civil Engineering and Urban Programing.LIU Y M,FU D,TONG Z X,et al,eds.London,2016.
[14]陈生水,傅中志,韩华强.一个考虑颗粒破碎的堆石料弹塑性本构模型[J].岩土工程学报,2011,33(10):1489-1495.(CHEN Sheng-shui,FU Zhong-zhi,HAN Hua-qiang.An elastoplastic model for rockfill materials considering particle breakage[J].Chinese Journal of Geotechnical Engineering,2011,33(10):1489-1495.(in Chinese))
[15]KIM M K,LADE P V.Single hardening constitutive model for frictional materials:I plastic potential function[J].Computers and Geotechnics,1988,5(4):307-324.
[16]COLLINS I F,KELLY P A.A thermomechanical analysis of a family of soil models[J].Géotechnique,2002,52(7):507-518.
[17]沈珠江.理论土力学[M].北京:中国水利水电出版社,2000.(SHEN Zhu-jiang.Theoretical soil mechanics[M].Beijing:China Waterpower Press,2005.(in Chinese))
[18]李国英,米占宽,傅华,等.混凝土面板堆石坝堆石料流变特性试验研究[J].岩土力学,2004,25(11):1712-1716.(LI Guo-ying,MI Zhan-kuan,FU Hua,et al.Experimental studies on rheological behaviors for rockfills in concrete faced rockfill dam[J].Rock and Soil Mechanics,2004,25(11):1712-1716.(in Chinese))