土工袋双轴压缩的离散元数值模拟
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摘要
鉴于土工袋材料介质不连续性的特点,采用离散元法模拟土工袋双轴压缩试验,从细观角度分析土工袋的力学特性。通过蒙特卡洛随机算法生成一定颗粒级配的土颗粒样本,计算时土颗粒间采用弹簧-阻尼器-滑块接触模型,袋子颗粒间采用皮筋-阻尼器接触模型。计算结果表明:土工袋的极限强度远大于无袋子土体的极限强度,土工袋破坏时的总体变形远大于无袋子土体破坏时的总体变形,且袋子颗粒间的张力呈非均匀分布;土工袋应力-应变的数值模拟结果与理论推导公式计算值吻合较好;竖向外力作用下,土工袋内部颗粒间力链由环状均匀分布向大主应力方向发展,颗粒位移呈对称性向两侧扩散,且袋子破坏是土工袋达到极限强度的直接原因。
Due to the discontinuity of soilbag materials,experiments of a soilbag under biaxial compression were modeled using discrete element method,and the mechanical characteristics of the soilbag were analyzed on a mesoscopic level.Monte-Carlo algorithm is introduced to randomly generate an assembly of soil particles with a certain grain composition. The contact between soil particles is simulated by a combination of a spring-dashpot-slider model,while the contact between bag particles is simulated by a rubber band-dashpot model. The results show that the bearing capacity of the soilbag is much higher than that of soil without a bag. When failure occurs,the overall deformation of the soilbag is also far higher than that of soil without a bag,and the tension between particles has a non-uniform distribution. The stress-strain relationship obtained from simulations agrees well with the theoretical formula. Under vertical loads,the intergranular force chains develop from the uniform circular distribution to the direction of the large principal stress,while the soil particles move to the both sides. Bag breakage is the direct reason for the soilbag to reach the ultimate strength.
Due to the discontinuity of soilbag materials,experiments of a soilbag under biaxial compression were modeled using discrete element method,and the mechanical characteristics of the soilbag were analyzed on a mesoscopic level.Monte-Carlo algorithm is introduced to randomly generate an assembly of soil particles with a certain grain composition. The contact between soil particles is simulated by a combination of a spring-dashpot-slider model,while the contact between bag particles is simulated by a rubber band-dashpot model. The results show that the bearing capacity of the soilbag is much higher than that of soil without a bag. When failure occurs,the overall deformation of the soilbag is also far higher than that of soil without a bag,and the tension between particles has a non-uniform distribution. The stress-strain relationship obtained from simulations agrees well with the theoretical formula. Under vertical loads,the intergranular force chains develop from the uniform circular distribution to the direction of the large principal stress,while the soil particles move to the both sides. Bag breakage is the direct reason for the soilbag to reach the ultimate strength.
引文
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[15]刘斯宏,姚仰平,孙其诚,等.基于细观结构的颗粒介质应力应变关系研究[J].科学通报,2009,54(11):1496-1503.(LIU Sihong,YAO Yangping,SUN Qicheng,et al.Microscopic study on stress-strain relation of granular materials[J].Chinese Science Bulletin,2009,54(11):1496-1503.(in Chinese))
[16]刘斯宏,卢廷浩.用离散单元法分析单剪实验中粒状体的剪切机理[J].岩土工程学报,2000,22(5):608-611.(LIU Sihong,LU Tinghao.Microscopic shear mechanism of granular materials in simple shear by DEM[J].Chinese Journal of Geotechnical Engineering,2000,22(5):608-611.(in Chinese))
[2]刘斯宏,松冈元.土工袋加固地基新技术[J].岩土力学,2007,28(8):1665-1670.(LIU Sihong,MATSUOKA H.A new earth reinforcement method by soilbags[J].Rock and Soil Mechanics,2007,28(8):1665-1670.(in Chinese))
[3]刘斯宏,高军军,王子健,等.土工袋技术在市政沟槽回填中的应用研究[J].岩土力学,2014,35(3):765-771.(LIU Sihong,GAO Junjun,WANG Zijian,et al.Application of soilbags to urban trench backfill[J].Rock and Soil Mechanics,2014,35(3):765-771.(in Chinese))
[4]高军军,刘斯宏,白福清.袋装淤泥土土工袋的强度变形研究[J].三峡大学学报(自然科学版),2014,36(1):33-36.(GAO Junjun,LIU Sihong,BAI Fuqing.Experimental study on strength and deformation properties of soilbags filled with mud soil[J].Journal of China Three Gorges University(Natural Sciences),2014,36(1):33-36.(in Chinese))
[5]高军军,刘斯宏,王柳江.竖向荷载下土工袋的有限元数值模拟[J].河海大学学报(自然科学版),2014,42(6):524-528.(GAO Junjun,LIU Sihong,WANGLiujiang.Numerical simulation of a soilbag under vertical loads by FEM[J].Journal of Hohai University(Natural Sciences),2014,42(6):524-528.(in Chinese))
[6]李玲君,刘斯宏,徐小东,等.袋内材料对土工袋动力特性参数影响的试验研究[J].岩土力学,2015,36(1):131-136.(LI Lingjun,LIU Sihong,XU Xiaodong,et al.Experimental study of effects of soil fills on dynamic characteristics parameters of soil-bags[J].Rock and Soil Mechanics,2015,36(1):131-136.(in Chinese))
[7]刘斯宏,樊科伟,陈笑林,等.土工袋层间摩擦特性试验研究[J].岩土工程学报,2016,38(10):1874-1880.(LIU Sihong,FAN Kewei,CHEN Xiaolin,et al.Experimental studies on interface friction characteristics of soilbags[J].Chinese Journal of Geotechnical Engineering,2016,38(10):1874-1880.(in Chinese))
[8]刘斯宏,王柳江,李卓,等.土工袋加固软土地基现场荷载试验的数值模拟[J].水利水电科技进展,2012,32(1):78-82.(LIU Sihong,WANG Liujiang,LI Zhuo,et al.Numerical simulation of in-situ loading tests on a soilbag-reinforced soft foundation[J].Advances in Science and Technology of Water Resources,2012,32(1):78-82.(in Chinese))
[9]ANSARI Y,MERIFIELD R,YAMAMOTO H,et al.Numerical analysis of soilbags under compression and cyclic shear[J].Computers and Geotechnics,2011,38(5):659-668.
[10]BINDER K.The Monte Carlo method for the study of phase transitions:a review of some recent progress[J].Journal of Computational Physics,1985,59(1):1-55.
[11]RUBINSTEIN R Y,KROESE D P.Simulation and the Monte Carlo method:student solutions manual[J]Technometrics,2012,24(2):167-168.
[12]PAKMAN A,PANINSKI L.Auxiliary-variable exac Hamiltonian Monte Carlo samplers for binary distributions[J].Statistics,2015:2490-2498.
[13]叶翠明,徐永福,邵介贤,等.环保节能型地基处理方法:土工袋的性能分析[J].土工基础,2008(1):2-4(YE Cuiming,XU Yongfu,SHAO Jiexian,et al.A new environmental protection and energy-saving earth reinforcement method:soilbags and its property[J].Soi Engineering and Foundation,2008(1):2-4.(in Chinese))
[14]孙其诚,辛海丽,刘建国,等.颗粒体系中的骨架及力链网络[J].岩土力学,2009,30(增刊1):83-87(SUN Qicheng,XIN Haili,LIU Jianguo,et al.Skeleton and force chain network in static granular material[J]Rock and Soil Mechanics,2009,30(Sup1):83-87.(in Chinese))
[15]刘斯宏,姚仰平,孙其诚,等.基于细观结构的颗粒介质应力应变关系研究[J].科学通报,2009,54(11):1496-1503.(LIU Sihong,YAO Yangping,SUN Qicheng,et al.Microscopic study on stress-strain relation of granular materials[J].Chinese Science Bulletin,2009,54(11):1496-1503.(in Chinese))
[16]刘斯宏,卢廷浩.用离散单元法分析单剪实验中粒状体的剪切机理[J].岩土工程学报,2000,22(5):608-611.(LIU Sihong,LU Tinghao.Microscopic shear mechanism of granular materials in simple shear by DEM[J].Chinese Journal of Geotechnical Engineering,2000,22(5):608-611.(in Chinese))