砂土液化及液化后流动特性试验研究
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摘要
根据流体力学中的绕球定常黏性流动理论,在振动台试验的基础上,设计了一套砂土液化及液化后流动特性的试验装置。在振动台模型箱的砂土中埋入可以水平滑动的钢球,当砂土发生液化时使钢球发生水平运动,通过测量钢球所受的阻力来反算液化及液化后砂土的表观动力黏度,进而研究液化及液化后砂土的流动特性。试验中考虑了砂土的初始相对密度、钢球的运动速率、液化后砂土的超孔压比等因素的影响。试验结果表明,液化及液化后状态下砂土的表观动力黏度随着应变率的增大而减小,液化砂土呈现出剪切稀化的非牛顿流体特性。随着液化后超孔压比的降低,表观动力黏度也逐渐增大,通常随着应变率的增大,表观动力黏度–超孔压比曲线逐渐变缓。
According to the theory of dropping ball viscosimeter,the test apparatus of flow characteristics of liquefied and post-liquefied sand is developed based on the shaking table tests.A steel sphere,embedded in the sand box,can be moved in the horizontal direction when the soil liquefaction occurs.Resistance force and velocity are measured during sphere dragging and apparent viscosity is evaluated.The initial relative density of the deposited sand,the velocity of the sphere and excess pore pressure ratio are the main factors in the tests.The results show that the apparent viscosity of the liquefied and post-liquefied sand decreases with the increase of the strain rate.The liquefied and post-liquefied sand is shear thinning non-Newtonian fluid.The apparent viscosity of the post-liquefied sand increases with the decrease of the excess pore pressure ratio,and the curve slope of the apparent viscosity vs.the excess pore pressure ratio decreases with the increase of the strain rate.
According to the theory of dropping ball viscosimeter,the test apparatus of flow characteristics of liquefied and post-liquefied sand is developed based on the shaking table tests.A steel sphere,embedded in the sand box,can be moved in the horizontal direction when the soil liquefaction occurs.Resistance force and velocity are measured during sphere dragging and apparent viscosity is evaluated.The initial relative density of the deposited sand,the velocity of the sphere and excess pore pressure ratio are the main factors in the tests.The results show that the apparent viscosity of the liquefied and post-liquefied sand decreases with the increase of the strain rate.The liquefied and post-liquefied sand is shear thinning non-Newtonian fluid.The apparent viscosity of the post-liquefied sand increases with the decrease of the excess pore pressure ratio,and the curve slope of the apparent viscosity vs.the excess pore pressure ratio decreases with the increase of the strain rate.
引文
[1]刘汉龙.土动力学与岩土地震工程[C]//第九届土力学及岩土工程学术会议论文集.北京:清华大学出版社,2003:56–68.(LIU Han-long.Soil dynamics and geotechnical earthquake engineering[C]//Proceedings of the9th Soil Mechanics and Geotechnical Engineering Conference.Beijing:Tsinghua University Press,2003:56–68.(in Chinese))
[2]The Committee of Soil Dynamics of Geotechnical Engineering Division.Definition of terms related to liquefaction[J].Journal of Geotechnical Engineering,ASCE,1978,104(GT9):1197–1120.
[3]陈育民,周云东.基于流体力学方法的砂土液化后研究进展[J].河海大学学报(自然科学版),2007,35(4):418–421.(CHEN Yu-min,ZHOU Yun-dong.Advance in sand postliquefaction research based on fluid mechanics method[J].Journal of Hohai University,2007,35(4):418–421.(in Chinese))
[4]SASAKI Y,TOWHATA I,TOKIDA K I,YAMADA K,MATSUMOTO H,TAMARI Y.Mechanism of permanent displacement of ground caused by seismic liquefaction[J].Soils and Foundations,1992,32(3):79–96.
[5]TOWHATA I,VARGAS-MONGE W,ORENSE R P,YAO M.Shaking table tests on subgrade reaction of pipe embedded in sandy liquefied subsoil[J].Soil Dynamics and Earthquake Engineering,1999,18:347–361.
[6]宮島昌克,北浦榺,北野豐.液化狀の程度による地盤物性值の變化に關する實驗[C]//日本土木學會第49回年次學術演講會,1994:548–549.(MIYAJIMA M,KITAURA M,KITANO Y.Model tests on variation of soil properties with the extent of liquefaction[C]//Proceeding of the Annual Conference of JSCE,1994:548–549.(in Japanese))
[7]宮島昌克,長谷川正道,北浦榺,等.液化狀に伴ぅ側方流動が地中構造物に及ばす影響に關する實驗的研究[C]//日本第九屆地震岩土工程研討會,1994:1363–1368.(MIYAJIMA M,HASEGAWA M,KITAURA M,et al.Experimental study on effects of liquefaction-induced lateral spreading on buried structures[C]//Proceeding of Ninth Japan Earthquake Engineering Symposium,1994:1363–1368.(in Japanese))
[8]MIYAJIMA M,KITAURA M,KOIKE T,HASEGAWA M.Experimental study on characteristics of liquefied ground flow[C]//The First International Conference on Earthquake Geotechnical Engineering,Rotterdam,A A Balkema,1995:969–974.
[9]TAMATE S,TOWHATA I.Numerical simulation of ground flow caused by seismic liquefaction[J].Soil Dynamics and Earthquake Engineering,1999,18:473–485.
[10]TOWHATA I,VARGAS-MONGE W,ORENSE R P,YAO M.Shaking table tests on subgrade reaction of pipe embeded in sandy liquefied subsoil[J].Soil Dynamics and Earthquake Engineering,1999,18:347–361.
[11]NISHIMURA S,TOWHATA I,HONDA T.Laboratory shear tests on viscous nature of liquefied sand[J].Soils and Foundations,2002,42(4):89–98.
[12]陈育民,刘汉龙,周云东.液化及液化后砂土的流动特性分析[J].岩土工程学报,2006,28(9):1139–1143.(CHEN Yu-min,LIU Han-long,ZHOU Yun-dong.Analysis on flow characteristics of liquefied and post-liquefied sand[J].Chinese Journal of Geotechnical Engineering,2006,28(9):1139–1143.(in Chinese))
[2]The Committee of Soil Dynamics of Geotechnical Engineering Division.Definition of terms related to liquefaction[J].Journal of Geotechnical Engineering,ASCE,1978,104(GT9):1197–1120.
[3]陈育民,周云东.基于流体力学方法的砂土液化后研究进展[J].河海大学学报(自然科学版),2007,35(4):418–421.(CHEN Yu-min,ZHOU Yun-dong.Advance in sand postliquefaction research based on fluid mechanics method[J].Journal of Hohai University,2007,35(4):418–421.(in Chinese))
[4]SASAKI Y,TOWHATA I,TOKIDA K I,YAMADA K,MATSUMOTO H,TAMARI Y.Mechanism of permanent displacement of ground caused by seismic liquefaction[J].Soils and Foundations,1992,32(3):79–96.
[5]TOWHATA I,VARGAS-MONGE W,ORENSE R P,YAO M.Shaking table tests on subgrade reaction of pipe embedded in sandy liquefied subsoil[J].Soil Dynamics and Earthquake Engineering,1999,18:347–361.
[6]宮島昌克,北浦榺,北野豐.液化狀の程度による地盤物性值の變化に關する實驗[C]//日本土木學會第49回年次學術演講會,1994:548–549.(MIYAJIMA M,KITAURA M,KITANO Y.Model tests on variation of soil properties with the extent of liquefaction[C]//Proceeding of the Annual Conference of JSCE,1994:548–549.(in Japanese))
[7]宮島昌克,長谷川正道,北浦榺,等.液化狀に伴ぅ側方流動が地中構造物に及ばす影響に關する實驗的研究[C]//日本第九屆地震岩土工程研討會,1994:1363–1368.(MIYAJIMA M,HASEGAWA M,KITAURA M,et al.Experimental study on effects of liquefaction-induced lateral spreading on buried structures[C]//Proceeding of Ninth Japan Earthquake Engineering Symposium,1994:1363–1368.(in Japanese))
[8]MIYAJIMA M,KITAURA M,KOIKE T,HASEGAWA M.Experimental study on characteristics of liquefied ground flow[C]//The First International Conference on Earthquake Geotechnical Engineering,Rotterdam,A A Balkema,1995:969–974.
[9]TAMATE S,TOWHATA I.Numerical simulation of ground flow caused by seismic liquefaction[J].Soil Dynamics and Earthquake Engineering,1999,18:473–485.
[10]TOWHATA I,VARGAS-MONGE W,ORENSE R P,YAO M.Shaking table tests on subgrade reaction of pipe embeded in sandy liquefied subsoil[J].Soil Dynamics and Earthquake Engineering,1999,18:347–361.
[11]NISHIMURA S,TOWHATA I,HONDA T.Laboratory shear tests on viscous nature of liquefied sand[J].Soils and Foundations,2002,42(4):89–98.
[12]陈育民,刘汉龙,周云东.液化及液化后砂土的流动特性分析[J].岩土工程学报,2006,28(9):1139–1143.(CHEN Yu-min,LIU Han-long,ZHOU Yun-dong.Analysis on flow characteristics of liquefied and post-liquefied sand[J].Chinese Journal of Geotechnical Engineering,2006,28(9):1139–1143.(in Chinese))
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