考虑孔隙率和不均匀系数的土石混合体颗粒流分析
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摘要
为研究低含石率情况下,由土体主导的土石混合体的力学特性,采用分层欠压和随机生成多边形相结合的建模方法,建立土石混合体颗粒流模型,提出不均匀系数作为衡量土石混合体非均质性的指标。通过室内试验校核了颗粒模型的细观参数,并开展双轴数值模拟试验,研究在低含石率情况下,含石率、土体孔隙率和不均匀系数3个因素对土石混合体力学特性的影响。结果表明:在低含石率情况下,土石混合体的强度受土体孔隙率影响较大,随着土体孔隙率的减小,土石混合体的强度有较大提高;块石的存在破坏了土体的均匀性和连续性,反而在低含石率情况下,随着含石率增大,土石混合体整体强度有微小减小的现象;土石混合体的不均匀系数对体应变影响较大,不均匀系数越大,体应变的膨胀现象越明显。
In order to study the mechanical properties of soil-rock mixtures dominated by the soil under a low rock content, the modeling method combining multi-layer method under compaction and random polygon generating method is adopted to establish the particle flow model of soil-rock mixture, and the inhomogeneous coefficient S is proposed as an index of the heterogeneity of soil-rock mixture. The mesoscopic parameters of the particle model were checked by a laboratory test, and the numerical simulation of the biaxial test was also carried out, for checking the effects of three factors on the mechanical properties of the soil-rock mixtures under the condition of low stone content, including the rock content, the porosity and the inhomogeneous coefficient S. In the case of low stone content, the strength of the soil-rock mixture is greatly influenced by the porosity of the soil. With the decrease of the soil porosity, the strength of the soil-rock mixtures is greatly improved. The existence of block stone destroys the uniformity and continuity of the soil. On the contrary, the overall strength of the soil-rock mixture decreases with the increase of the rock content. The inhomogeneous coefficient S has great influence on bulk strain. The greater the coefficient of heterogeneity is, the more obvious the expansion of volumetric strain is.
In order to study the mechanical properties of soil-rock mixtures dominated by the soil under a low rock content, the modeling method combining multi-layer method under compaction and random polygon generating method is adopted to establish the particle flow model of soil-rock mixture, and the inhomogeneous coefficient S is proposed as an index of the heterogeneity of soil-rock mixture. The mesoscopic parameters of the particle model were checked by a laboratory test, and the numerical simulation of the biaxial test was also carried out, for checking the effects of three factors on the mechanical properties of the soil-rock mixtures under the condition of low stone content, including the rock content, the porosity and the inhomogeneous coefficient S. In the case of low stone content, the strength of the soil-rock mixture is greatly influenced by the porosity of the soil. With the decrease of the soil porosity, the strength of the soil-rock mixtures is greatly improved. The existence of block stone destroys the uniformity and continuity of the soil. On the contrary, the overall strength of the soil-rock mixture decreases with the increase of the rock content. The inhomogeneous coefficient S has great influence on bulk strain. The greater the coefficient of heterogeneity is, the more obvious the expansion of volumetric strain is.
引文
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[2]唐建一,徐东升,刘华北.含石量对土石混合体剪切特性的影响[J].岩土力学,2018,39(1):93-102.(TANG Jianyi,XUDongsheng,LIU Huabei.Mesomechanics research of large direct shear test on soil and rock aggregate mixture with particle flow code simulation[J].Rock and Soil Mechanics,2018,39(1):93-102.(in Chinese))
[3]夏加国,胡瑞林,祁生文,等.含超径颗粒土石混合体的大型三轴剪切试验研究[J].岩石力学与工程学报,2017,36(8):2031-2039.(XIA Jiaguo,HU Ruilin,QI Shengwen,et al.Large-scale triaxial shear testing of soil rock mixtures containing oversized particles[J].Chinese Journal of Rock Mechanics and Engineering,2017,36(8):2031-2039.(in Chinese))
[4]胡峰,李志清,胡瑞林,等.基于大型直剪试验的土石混合体剪切带变形特征试验研究[J].岩石力学与工程学报,2018,37(3):766-778.(HU Feng,LI Zhiqing,HU Ruilin,et al.Research on the deformation characteristics of shear band of soil-rock mixture based on large scale direct shear test[J].Chinese Journal of Rock Mechanics and Engineering,2018,37(3):766-778.(in Chinese))
[5]金磊,曾亚武.土石混合体宏细观力学特性和变形破坏机制的三维离散元精细模拟[J].岩石力学与工程学报,2018,37(6):1540-1550.(JIN Lei,ZENG Yawu.Refined simulation for macro-and meso-mechanical properties and failure mechanism of soil-rock mixture by 3D DEM[J].Chinese Journal of Rock Mechanics and Engineering,2018,37(6):1540-1550.(in Chinese))
[6]陈立,张朋,郑宏.土石混合体二维细观结构模型的建立与数值流形法模拟[J].岩土力学,2017,38(8):2402-2410.(CHEN Li,ZHANG Peng,ZHENG Hong.Mesostructure modeling of soil-rock mixtures and study of its mesostructural mechanics based on numerical manifold method[J].Rock and Soil Mechanics,2017,38(8):2402-2410.(in Chinese))
[7]JIANG Mingjing,KONRAD J M,LEROUEIL S.An efficient technique for generating homogeneous specimens for DEM studies[J].Computers&Geotechnics,2003,30(7):579-597.
[8]田湖南,焦玉勇,王浩,等.土石混合体力学特性的颗粒离散元双轴试验模拟研究[J].岩石力学与工程学报,2015,34(增刊1):3564-3573.(TIAN Hunan,JIAO Yuyong,WANG Hao,et al.Research on biaxial test of mechanical characteristics on soil-rock aggregate(sra)based on particle flow code simulation[J].Chinese Journal of Rock Mechanics and Engineering,2015,34(Sup1):3564-3573.(in Chinese))
[9]孙立国,杜成斌,戴春霞.大体积混凝土随机骨料数值模拟[J].河海大学学报(自然科学版),2005,33(3):291-295.(SUN Liguo,DU Chengbin,DAI Chunxia.Numerical simulation of random aggregate model for mass concrete[J].Journal of Hohai University(Natural Sciences),2005,33(3):291-295.(in Chinese))
[10]徐文杰,胡瑞林,岳中崎.土-石混合体随机细观结构生成系统的研发及其细观结构力学数值试验研究[J].岩石力学与工程学报,2008,28(8):1652-1665.(XU Wenjie,HU Ruilin,YUE Zhongqi.Development of random mesostructure generating system of soil-rock mixture and study of its mesostructural mechanics based on numerical test[J].Chinese Journal of Rock Mechanics and Engineering,2008,28(8):1652-1665.(in Chinese))
[11]薛亚东,刘忠强,吴坚.崩积混合体直剪试验与PFC 2D数值模拟分析[J].岩土力学,2014,35(增刊2):587-592.(XUE Yadong,LIU Zhongqiang,WU Jian.Direct shear tests and PFC 2D numerical simulation of colluvial mixture[J].Rock and Soil Mechanics,2014,35(Sup2):587-592.(in Chinese))
[12]MEDLEY E W.Estimating block size distributions of mélanges and similar block-in-matrix rocks(bimrocks)[C]//NARMS.Proceedings of the 5th North American Rock Mechanics Symposium.Toronto:University of Toronto Press,2002:599-606.
[13]徐安权,徐卫亚,石崇.基于小波变换的数字图像技术在堆积体模拟中的应用[J].岩石力学与工程学报,2011,30(5):1007-1015.(XU Anquan,XU Weiya,SHI Chong.Application of digital image technology to simulation of talus deposit based on wavelet transform[J].Chinese Journal of Rock Mechanics and Engineering,2011,30(5):1007-1015.(in Chinese))
[14]COLI N,BERRY P,BOLDINI D.In situ non-conventional shear tests for the mechanical characterisation of a bimrock[J].International Journal of Rock Mechanics&Mining Sciences,2011,48(1):95-102.
[15]秦红玉,刘汉龙,高玉峰,等.粗粒料强度和变形的大型三轴试验研究[J].岩土力学,2004,25(10):1575-1580.(QINHongyu,LIU Hanlong,GAO Yufeng,et al.Research on strength and deformation behavior of coarse Aggregates based on largescale triaxial tests[J].Rock and Soil Mechanics,2004,25(10):1575-1580.(in Chinese))
[16]CHARLES J A,WATTS K S.The influence of confining pressure on the shear strength of compacted rockfill[J].Géotechnique,1980,30(4):353-367.