统一模型下粘性土和砂性土液化特性数值研究
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摘要
考虑到土体介质材料经历弹性卸载后即进入超固结状态,而其反过来又能影响土体的力学与抗液化特性,通过考虑超固结因素的影响,在统一下负荷面剑桥模型下对砂性土与粘性土的力学与抗液化特性进行了数值试验对比研究。结果表明,与粘性土相比,砂性土在加载过程中表现出更高的非线性特征与可压缩性,且在非排水加载下更容易引发屈服和液化。通过考虑土体超固结因素的影响以及不同土体条件下超固结比演化规律的差异,下负荷面剑桥模型在统一理论框架下很好的模拟出了砂性土与粘性土间力学与抗液化能力的差异。同时考虑到土体超固结状态与密实度间的关系,模型也从超固结状态的角度很好的解释了土体抗液化能力与相对密度的关系,且与液化试验实测结果取得了较高的一致性。
Considering soil turns into overconsolidated state once experiences stress unloading under cyclic loading,and the state of overconsolidation could affects the mechanical properties and liquefaction characteristics in turn,in this paper,with taking the influence of overconsolidation factor into consideration,comparative numerical studies of mechanical properties and liquefaction characteristics between clayey and sandy soils are carried out in the unified subloading surface Cam-clay model.The research results show that compared with clayey soil,sandy soil has higher compressibility,stronger nonlinear characteristics,and more tends to liquefy under undrained cyclic loading test.Through precisely simulates the effect of overconsolidation,as well as the evolution of OCR,the different mechanical properties and liquefaction resistance between clayey and sandy soils are well simulated in the unified theoretical framework.At the same time,considering the relationship between overconsolidation and relative density of soil,the model also well explained the relationship between liquefaction resistance and overconsolidated state of soil,and achieved high consistency with the observed experimental liquefaction test results.
Considering soil turns into overconsolidated state once experiences stress unloading under cyclic loading,and the state of overconsolidation could affects the mechanical properties and liquefaction characteristics in turn,in this paper,with taking the influence of overconsolidation factor into consideration,comparative numerical studies of mechanical properties and liquefaction characteristics between clayey and sandy soils are carried out in the unified subloading surface Cam-clay model.The research results show that compared with clayey soil,sandy soil has higher compressibility,stronger nonlinear characteristics,and more tends to liquefy under undrained cyclic loading test.Through precisely simulates the effect of overconsolidation,as well as the evolution of OCR,the different mechanical properties and liquefaction resistance between clayey and sandy soils are well simulated in the unified theoretical framework.At the same time,considering the relationship between overconsolidation and relative density of soil,the model also well explained the relationship between liquefaction resistance and overconsolidated state of soil,and achieved high consistency with the observed experimental liquefaction test results.
引文
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[2]Memarpour M M,Kimiaei M,Shayanfar M,et al.Cyclic lateral response of pile foundations in offshore platforms[J].Computers and Geotechnics,2012(42):180-192.
[3]王睿,张建民,张嘎.液化地基侧向流动引起的桩基础破坏分析[J].岩土力学,2011,32(增1):501-506.Wang R,Zhang J M,Zhang G.Analysis of failure of piled foundation due to lateral spreading in liquefied soils[J].Rock and Soil Mechanics,2011,32(Sup 1):501-506.(in Chinese)
[4]Ye J H,Wang G.Seismic dynamics of offshore breakwater on liquefiable seabed foundation[J].Soil Dynamics and Earthquake Engineering,2015,76:86-99.
[5]Fukusumi T,Ozaki H,Kobac M.Influence of the ground profile on the reduction of earthquake motion at the filled man-made islands in the Kobe harbor during the 1995Hyogoken Nambu earthquake[J].Journal of Soil Dynamics and Earthquake Engineering,2002,22:893-899.
[6]Maurer B W,Green R A,Cubrinovski M,et al.Finescontent effects on liquefaction hazard evaluation for infrastructure in Christchurch,New Zealand[J].Soil Dynamics and Earthquake Engineering,2015,76:58-68.
[7]Boulanger R W,Meyers M W,Mejia L H,et al.Behavior of a fine-grained soil during the Loma Prieta earthquake[J].Canadian Geotechnical Journal,1998,35:146-158.
[8]Pan H,Chen G X,Liu H L,et al.Behavior of large post-liquefaction deformation in saturated Nanjing fine sand[J].Earthquake Engineering and Engineering Vibration,2011,10(2):187-193.
[9]汪闻韶.土的动力强度与液化特性[M].北京:中国水电出版社,1996.Wang W Sh.Dynamic strength and liquefaction characteristics of soil[M].Beijing:China Electric Power Press,1996.(in Chinese)
[10]孙锐.液化土层地震动和场地液化识别方法研究[D].哈尔滨:中国地震局工程力学研究所,2006.Sun R.Study on seismic ground motion on liquefiable soil layer and site liquefaction detection[D].Harbin:Institute of Engineering Mechaincs,China Seismological Bureau,2006.(in Chinese)
[11]董林.黄土及一般含细粒土体液化判别方法研究[D].哈尔滨:中国地震局工程力学研究所,2016.Dong L.Study on mechanical characteristics of loess and liquefaction discrimination methods for widespread fines-containing soils institute of engineering mechanics[D].Harbin:Institute of Engineering Mechanics,China Seismological Bureau,2016.(in Chinese)
[12]姚仰平,张丙印,朱俊高.土的基本特性、本构关系及数值模拟研究综述[J].土木工程学报,2012,45(3):127-150.Yao Y P,Zhang B Y,Zhu J G.Behaviors,constitutive models and numerical simulation of soils[J].China Civil Engineering Journal,2012,45(3):127-150.(in Chinese)
[13]Choo H,Burns S E.Effect of overconsolidation ratio on dynamic properties of binary mixtures of silica particles[J].Soil Dynamics and Earthquake Engineering,2014,60:44-50.
[14]张锋.计算土力学[M].北京:人民交通出版社,2007.Zhang F.Computational soil mechanics[M].Beijing:China Communication Press,2007.(in Chinese)
[15]Nakai T,Hinokio M.A simple elastoplastic model for normally and over consolidated soils with unified material parameters[J].Soils and Foundations,2004,44(2):53-70.
[16]Asaoka A,Nakano M,Noda T.A super/subloading yield surface approach to compaction/liquefaction of sand and secondary consolidation of clay[C]//Geomechanics II:Testing,Modeling and Simulation,Proceeding of the Second GI-JGS workshop.Osaka:ASCEGeotechnical Special Publication,2006:201-218.
[17]王谦,王兰民,王峻,等.基于密度控制理论的饱和黄土地基抗液化处理指标研究[J].岩土工程学报,2013,35(增2):844-847.Wang Q,Wang L M,Wang J,et al.Indices of antiliquefaction treatment of saturated compacted loess foundation based on theory of density control[J].Chinese Journal of Geotechnical Engineering,2013,35(Sup 2):844-847.(in Chinese)