格栅–砂土界面宏细观关联性与加筋性能评价方法研究
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摘要
土工格栅与填料间作用特性对加筋土结构设计至关重要。为研究界面宏–细观力学响应关联及填料粒径对加筋效果的影响,采用三维离散元方法对三向土工格栅拉拔过程进行仿真模拟,系统分析拉拔作用下筋材及颗粒的力学响应,揭示拉拔力发展与细观组构指标演化规律,建立基于拉拔试验结果的格栅加筋性能评价方法。研究结果表明,界面颗粒速度场可即时反映筋土相互作用;选取组构演化系数描述宏观强度的发展是合适的;在一定粒径范围内,格栅加筋性能主要受控于颗粒体系比表面积,加筋土临塑荷载随填料粒径的增大而降低。
The interface characteristic of geogrid and compacted materials plays an important role in the design of reinforced soil structures. The pull-out test of triaxial geogrid was conducted by 3-D discrete element method to investigate the correlation between macro and meso mechanical responses. Simultaneously,the influence of particle size on reinforcement effect was discussed. The mechanical behavior of reinforced soil and geogrid under pull-out loading was systematically analyzed. The evolution law of the pull-out force and mesoscopic fabric anisotropy indices was shown. Based on the pull-out test results,an assessment method was established to estimate the reinforcement effect of geogrid. Numerical results reveal that the velocity vector of particles in the interfaces can reflect the interaction between geogrid and soil instantaneously. The fabric anisotropy coefficient is suitable to describe the development of macroscopic strength. In a certain particle size scope,the reinforcement effect would be primarily controlled by the specific surface area of grain system and the critical edge load of reinforced soil would decrease with the increase of particle size.
The interface characteristic of geogrid and compacted materials plays an important role in the design of reinforced soil structures. The pull-out test of triaxial geogrid was conducted by 3-D discrete element method to investigate the correlation between macro and meso mechanical responses. Simultaneously,the influence of particle size on reinforcement effect was discussed. The mechanical behavior of reinforced soil and geogrid under pull-out loading was systematically analyzed. The evolution law of the pull-out force and mesoscopic fabric anisotropy indices was shown. Based on the pull-out test results,an assessment method was established to estimate the reinforcement effect of geogrid. Numerical results reveal that the velocity vector of particles in the interfaces can reflect the interaction between geogrid and soil instantaneously. The fabric anisotropy coefficient is suitable to describe the development of macroscopic strength. In a certain particle size scope,the reinforcement effect would be primarily controlled by the specific surface area of grain system and the critical edge load of reinforced soil would decrease with the increase of particle size.
引文
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[15]马刚,周伟,常晓林,等.粗粒土与结构接触面特性的离散-连续耦合数值研究[J].岩土力学,2012,33(11):3 454–3 464.(MA Gang,ZHOU Wei,CHANG Xiaolin,et al.Numerical study of behavior of interface between coarse-grained soil and structure by discrete-continuum coupling method[J].Rock and Soil Mechanics,2012,33(11):3 454–3 464.(in Chinese))
[16]梁波,杨有海.加筋砂土地基承载力理论与试验分析研究[J].岩土工程学报,2008,30(1):123–127.(LIANG Bo,YANG Youhai.Theory and experiment on bearing capacity of reinforced sandy soil[J].Chinese Journal of Geotechnical Engineering,2008,30(1):123–127.(in Chinese))
[17]包承纲.土工合成材料界面特性的研究和试验验证[J].岩石力学与工程学报,2006,25(9):1 735–1 744.(BAO Chenggang.Study on interface behavior of geosynthetics and soil[J].Chinese Journal of Rock Mechanics and Engineering,2006,25(9):1 735–1 744.(in Chinese))
[18]罗勇,龚晓南,连峰.三维离散颗粒单元模拟无黏性土的工程力学性质[J].岩土工程学报,2008,30(2):292–297.(LUO Yong,GONG Xiaonan,LIAN Feng.Simulation of mechanical behaviors of granular materials by three-dimensional discrete element method based on particle flow code[J].Chinese Journal of Geotechnical Engineering,2008,30(2):292–297.(in Chinese))
[19]张克恭,刘松玉.土力学[M].北京:中国建筑工业出版社,2010:238–241.(ZHANG Kegong,LIU Songyu.Soil mechanics[M].Beijing:China Architecture and Building Press,2010:238–241.(in Chinese))
[2]王协群,张俊峰,邹维列,等.格栅-土界面抗剪强度模型及其影响因素[J].土木工程学报,2013,46(4):133–141.(WANG Xiequn,ZHANG Junfeng,ZOU Weilie,et al.A shear strength model of geogrid-soil interface and its influence factors[J].China Civil Engineering Journal,2013,46(4):133–141.(in Chinese))
[3]周健,王家全,孔祥利,等.砂土颗粒与土工合成材料接触界面细观研究[J].岩土工程学报,2010,32(1):61–67.(ZHOU Jian,WANG Jiaquan,KONG Xiangli,et al.Mesoscopic study of the interface between sandy soil and geosynthetics[J].Chinese Journal of Geotechnical Engineering,2010,32(1):61–67.(in Chinese))
[4]WANG Z,JACOBS F,ZIEGLER M.Visualization of load transfer behaviour between geogrid and sand using PFC2D[J].Geotextiles and Geomembranes,2014,42(2):83–90.
[5]CHEN C,MCDOWELL G R,THOM N H.Investigating geogrid-reinforced ballast:Experimental pull-out tests and discrete element modelling[J].Soils and Foundations,2014,54(1):1–11.
[6]DONG Y L,HAN J,BAI X H.Numerical analysis of tensile behavior of geogrids with rectangular and triangular apertures[J].Geotextiles and Geomembranes,2011,29(2):83–91.
[7]CHEN C,MCDOWELL G R,THOM N H.Discrete element modelling of cyclic loads of geogrid-reinforced ballast under confined and unconfined conditions[J].Geotextiles and Geomembranes,2012,35(12):76–86.
[8]苗晨曦,郑俊杰,崔明娟,等.节点突起影响格栅加筋性能的离散元研究[J].岩土力学,2014,35(4):1 181–1 186.(MIAO Chenxi,ZHENG Junjie,CUI Mingjuan,et al.Study on the influence of joint protuberance on geogrid reinforcement performance by discrete element method[J].Rock and Soil Mechanics,2014,35(4):1 181–1 186.(in Chinese))
[9]ZHOU J,JIAN Q,ZHANG J,et al.Coupled 3D discrete-continuum numerical modeling of pile penetration in sand[J].Journal of Zhejiang University Science A,2012,13(1):44–55.
[10]周健,黄金,张姣,等.基于三维离散–连续耦合方法的分层介质中桩端刺入数值模拟[J].岩石力学与工程学报,2012,31(12):2 564–2 571.(ZHOU Jian,HUANG Jin,ZHANG Jiao,et al.Coupled 3D discrete-continuum numerical simulation of pile tip penetration in layered media[J].Chinese Journal of Rock Mechanics and Engineering,2012,31(12):2 564–2 571.(in Chinese))
[11]ZHANG M X,QIU C C,JAVADI A A,et al.Discrete-element method simulation of a model test of an embankment reinforced with horizontal-vertical inclusions[J].Geosynthetics International,2013,20(4):238–251.
[12]郑俊杰,苗晨曦,谢明星,等.界面特性及填料粒径影响格栅加筋性能的离散元研究[J].岩土工程学报,2013,35(8):1 423–1 428.(ZHENG Junjie,MIAO Chenxi,XIE Mingxing,et al.Interface properties and influence of particle size on geogrid reinforcement performance by DEM[J].Chinese Journal of Geotechnical Engineering,2013,35(8):1 423–1 428.(in Chinese))
[13]刘续,唐晓武,申昊,等.加筋土结构中筋材拉拔力的分布规律研究[J].岩土工程学报,2013,35(4):800–804.(LIU Xu,TANG Xiaowu,SHEN Hao,et al.Stress distribution of reinforcement of reinforced soil structure under drawing force[J].Chinese Journal of Geotechnical Engineering,2013,35(4):800–804.(in Chinese))
[14]史旦达,周健,刘文白,等.砂土直剪力学性状的非圆颗粒模拟与宏细观机理研究[J].岩土工程学报,2010,32(10):1 557–1 565.(SHI Danda,ZHOU Jian,LIU Wenbai,et al.Exploring macro-and micro-scale responses of sand in direct shear tests by numerical simulations using non-circular particles[J].Chinese Journal of Geotechnical Engineering,2010,32(10):1 557–1 565.(in Chinese))
[15]马刚,周伟,常晓林,等.粗粒土与结构接触面特性的离散-连续耦合数值研究[J].岩土力学,2012,33(11):3 454–3 464.(MA Gang,ZHOU Wei,CHANG Xiaolin,et al.Numerical study of behavior of interface between coarse-grained soil and structure by discrete-continuum coupling method[J].Rock and Soil Mechanics,2012,33(11):3 454–3 464.(in Chinese))
[16]梁波,杨有海.加筋砂土地基承载力理论与试验分析研究[J].岩土工程学报,2008,30(1):123–127.(LIANG Bo,YANG Youhai.Theory and experiment on bearing capacity of reinforced sandy soil[J].Chinese Journal of Geotechnical Engineering,2008,30(1):123–127.(in Chinese))
[17]包承纲.土工合成材料界面特性的研究和试验验证[J].岩石力学与工程学报,2006,25(9):1 735–1 744.(BAO Chenggang.Study on interface behavior of geosynthetics and soil[J].Chinese Journal of Rock Mechanics and Engineering,2006,25(9):1 735–1 744.(in Chinese))
[18]罗勇,龚晓南,连峰.三维离散颗粒单元模拟无黏性土的工程力学性质[J].岩土工程学报,2008,30(2):292–297.(LUO Yong,GONG Xiaonan,LIAN Feng.Simulation of mechanical behaviors of granular materials by three-dimensional discrete element method based on particle flow code[J].Chinese Journal of Geotechnical Engineering,2008,30(2):292–297.(in Chinese))
[19]张克恭,刘松玉.土力学[M].北京:中国建筑工业出版社,2010:238–241.(ZHANG Kegong,LIU Songyu.Soil mechanics[M].Beijing:China Architecture and Building Press,2010:238–241.(in Chinese))