考虑残余体应变的土石坝地震永久变形分析
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摘要
地震永久变形是评价土石坝抗震稳定性的一个重要依据,其合理计算需要同时考虑材料的残余体积应变和残余剪切应变的影响。因此,在过去提出的永久变形等效节点力计算方法的基础上,通过考虑剪切压缩耦合作用来反映残余体积应变对地震永久变形的影响,并推导了相应的模量矩阵,明确了参数选择和计算步骤。对典型单元体的残余变形模式进行了分析,计算得到的剪切应变和体积应变大小均与理论值相符,验证了模量矩阵的可靠性。在此基础上,对心墙堆石坝和面板堆石坝的算例进行了计算,重点分析了竖直向、顺河向和横河向3个方向永久变形分布,并与实测规律进行比较。计算结果表明,考虑残余体应变之后,所提方法能够反映土石坝地震永久变形以沉降为主、水平变形相对较小的特点,可更为合理地反映地震永久变形的规律。
The earthquake induced permanent deformation is a key index for aseismic safety evaluation of rockfill dam.In order to calculate the permanent deformation reasonably,both residual volumetric strain and residual shear strain induced by the earthquake loading should be taken into account.For this reason,the method presented by LIU Han-long is modified.In the modified method,the residual volumetric strain is modeled by a shear-dilation-based approach.The derivation of the dilatancy modulus matrix is given in detail;and the calculation parameters and the analysis steps are also introduced.To test the reliability of dilatancy modulus matrix,the permanent deformation mode of a typical element is analyzed,the computed shear strain and volumetric strain are in good coincidence with the theoretical values.After that,the proposed method is used to calculate the earthquake induced permanent deformation of a core rockfill dam and a concrete faced rockfill dam.The computed distributions of the vertical,longitudinal and transversal permanent displacements are studied in detail.By comparing with the measured results,it is found that the dam deformations are mainly residual settlement;and the horizontal displacements are relatively small.It is proved that the proposed method can catch the features of the permanent deformation behavior of rockfill dam and it can give more reasonable results.
The earthquake induced permanent deformation is a key index for aseismic safety evaluation of rockfill dam.In order to calculate the permanent deformation reasonably,both residual volumetric strain and residual shear strain induced by the earthquake loading should be taken into account.For this reason,the method presented by LIU Han-long is modified.In the modified method,the residual volumetric strain is modeled by a shear-dilation-based approach.The derivation of the dilatancy modulus matrix is given in detail;and the calculation parameters and the analysis steps are also introduced.To test the reliability of dilatancy modulus matrix,the permanent deformation mode of a typical element is analyzed,the computed shear strain and volumetric strain are in good coincidence with the theoretical values.After that,the proposed method is used to calculate the earthquake induced permanent deformation of a core rockfill dam and a concrete faced rockfill dam.The computed distributions of the vertical,longitudinal and transversal permanent displacements are studied in detail.By comparing with the measured results,it is found that the dam deformations are mainly residual settlement;and the horizontal displacements are relatively small.It is proved that the proposed method can catch the features of the permanent deformation behavior of rockfill dam and it can give more reasonable results.
引文
[1]刘汉龙,费康,高玉峰.边坡地震稳定性时程分析方法[J].岩土力学,2003,24(4):553-556.LIU Han-long,FEI Kang,GAO Yu-feng.Time historyanalysis method of slope seismic stability[J].Rock andSoil Mechanics,2003,24(4):553-556.
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[10]刘汉龙,杨贵,陈育民.筑坝反滤料动剪切模量和阻尼比影响因素试验研究[J].岩土力学,2010,31(7):2030-2034,2039.LIU Han-long,YANG Gui,CHEN Yu-min.Experimentalstudy of factors influencing dynamic shear modulus anddamping ratio of dam inverted filler[J].Rock and SoilMechanics,2010,31(7):2030-2034,2039.
[11]BELKHATIRA M,ARABA A,DELLAA N,et al.Influence of inter-granular void ratio on monotonic andcyclic undrained shear response of sandy soils[J].Comptes Rendus Mecanique,2010,338(5):290-303.
[12]邹德高,孟凡伟,孔宪京,等.堆石料残余变形特性研究[J].岩土工程学报,2008,30(6):807-812.ZOU De-gao,MENG Fan-wei,KONG Xian-jing,et al.Residual deformation behavior of rock-fill materials[J].Chinese Journal of Geotechnical Engineering,2008,30(6):807-812.
[13]宋胜武,蔡德文.汶川大地震紫坪铺混凝土面板堆石坝震害现象与变形监测分析[J].岩石力学与工程学报,2009,28(4):840-849.SONG Sheng-wu,CAI De-wen.Earthquake damagephenomena and deformation monitoring analysis forconcrete faced rockfill dam at Zipingpu project duringWenchuan earthquake[J].Chinese Journal of RockMechanics and Engineering,2009,28(4):840-849.
[14]章为民,王年香,顾行文,等.土石坝坝顶加固的永久变形机理及其离心模型试验验证[J].水利水运工程学报,2011,(1):22-27.ZHANG Wei-min,WANG Nian-xiang,GU Xing-wen,et al.Deformation mechanism study of top reinforcement of theearth-rock-fill dam and its verification by the centrifugemodel test[J].Hydro-Science and Engineering,2011,(1):22-27.
[15]刘小生,王钟宁,汪小刚,等.面板坝大型振动台模型试验与动力分析[M].北京:中国水利水电出版社,2005.
[16]赵剑明,贾金生,李洪,等.考虑前期震动影响的紫坪铺面板坝震后抗震安全评价[J].水力发电学报,2012,31(1):82-87.ZHAO Jian-ming,JIA Jin-sheng,LI Hong,et al.Assessment of the post-earthquake safety of ZipingpuCFRD considering pre-vibration effect[J].Journal ofHydroelectric Engineering,2012,31(1):82-87.
[17]朱晟,杨鸽,周建平,等.“5.12”汶川地震紫坪铺面板堆石坝静动力初步反演研究[J].四川大学学报(工程科学版),2010,42(5):113-119.ZHU Sheng,YANG Ge,ZHOU Jian-ping,et al.Backanalysis on static and dynamic characteristics of ZipingpuCFRD under"5.12"Wenchuan Earthquake[J].Journalof Sichuan University(Engineering Science Edition),2010,42(5):113-119.
[2]ROBERT S,RAFAEL B.Design implications of thevertical pseudo-static coefficient in slope analysis[J].Computers and Geotechnics,2008,35(1):86-96.
[3]NEWMARK N M.Effects of earthquakes on dams andembankments[J].Geotechnique,1965,15(2):139-160.
[4]刘汉龙.土动力学与土工抗震研究进展综述[J].土木工程学报,2012,45(4):148-164.LIU Han-long.A review of recent advances in soildynamics and geotechnical earthquake engineering[J].China Civil Engineering Journal,2012,45(4):148-164.
[5]沈珠江,徐刚.堆石料的动力变形特性[J].水利水运科学研究,1996,(2):143-150.SHEN Zhu-jiang,XU Gang.Deformation behavior ofrock materials under cyclic loading[J].Journal ofNanjing Hydraulic Research Institute,1996,(2):143-150.
[6]赵剑明,陈宁,常亚屏,等.龙首二级面板堆石坝地震永久变形分析[J].世界地震工程,2003,19(44):57-62.ZHAO Jian-ming,CHEN Ning,CHANG Ya-ping,et al.Study on earthquake-induced permanent deformation ofLongshou CFRD[J].World Earthquake Engineering,2003,19(44):57-62.
[7]刘汉龙,陆兆溱,钱家欢.土石坝地震永久变形分析[J].河海大学学报(自然科学版),1996,24(1):91-96.LIU Han-long,LU Zhao-zhen,QIAN Jia-huan.Earthquake-induced permanent deformation of earth-rockdams[J].Journal of Hohai University(NaturalSciences),1996,24(1):91-96.
[8]朱晟,周建波.粗粒筑坝材料的动力变形特性[J].岩土力学,2010,31(5):1375-1380.ZHU Sheng,ZHOU Jian-bo.Deformation behavior ofcoarse grained materials under cyclic loading[J].Rockand Soil Mechanics,2010,(5):1375-1380.
[9]杨贵,刘汉龙,陈育民,等.堆石料动力变形特性的尺寸效应研究[J].水力发电学报,2009,28(5):121-126.YANG Gui,LIU Han-long,CHEN Yu-min,et al.Research on size effect of rock-fill materials on dynamicdeformation property[J].Journal of HydroelectricEngineering,2009,28(5):121-126.
[10]刘汉龙,杨贵,陈育民.筑坝反滤料动剪切模量和阻尼比影响因素试验研究[J].岩土力学,2010,31(7):2030-2034,2039.LIU Han-long,YANG Gui,CHEN Yu-min.Experimentalstudy of factors influencing dynamic shear modulus anddamping ratio of dam inverted filler[J].Rock and SoilMechanics,2010,31(7):2030-2034,2039.
[11]BELKHATIRA M,ARABA A,DELLAA N,et al.Influence of inter-granular void ratio on monotonic andcyclic undrained shear response of sandy soils[J].Comptes Rendus Mecanique,2010,338(5):290-303.
[12]邹德高,孟凡伟,孔宪京,等.堆石料残余变形特性研究[J].岩土工程学报,2008,30(6):807-812.ZOU De-gao,MENG Fan-wei,KONG Xian-jing,et al.Residual deformation behavior of rock-fill materials[J].Chinese Journal of Geotechnical Engineering,2008,30(6):807-812.
[13]宋胜武,蔡德文.汶川大地震紫坪铺混凝土面板堆石坝震害现象与变形监测分析[J].岩石力学与工程学报,2009,28(4):840-849.SONG Sheng-wu,CAI De-wen.Earthquake damagephenomena and deformation monitoring analysis forconcrete faced rockfill dam at Zipingpu project duringWenchuan earthquake[J].Chinese Journal of RockMechanics and Engineering,2009,28(4):840-849.
[14]章为民,王年香,顾行文,等.土石坝坝顶加固的永久变形机理及其离心模型试验验证[J].水利水运工程学报,2011,(1):22-27.ZHANG Wei-min,WANG Nian-xiang,GU Xing-wen,et al.Deformation mechanism study of top reinforcement of theearth-rock-fill dam and its verification by the centrifugemodel test[J].Hydro-Science and Engineering,2011,(1):22-27.
[15]刘小生,王钟宁,汪小刚,等.面板坝大型振动台模型试验与动力分析[M].北京:中国水利水电出版社,2005.
[16]赵剑明,贾金生,李洪,等.考虑前期震动影响的紫坪铺面板坝震后抗震安全评价[J].水力发电学报,2012,31(1):82-87.ZHAO Jian-ming,JIA Jin-sheng,LI Hong,et al.Assessment of the post-earthquake safety of ZipingpuCFRD considering pre-vibration effect[J].Journal ofHydroelectric Engineering,2012,31(1):82-87.
[17]朱晟,杨鸽,周建平,等.“5.12”汶川地震紫坪铺面板堆石坝静动力初步反演研究[J].四川大学学报(工程科学版),2010,42(5):113-119.ZHU Sheng,YANG Ge,ZHOU Jian-ping,et al.Backanalysis on static and dynamic characteristics of ZipingpuCFRD under"5.12"Wenchuan Earthquake[J].Journalof Sichuan University(Engineering Science Edition),2010,42(5):113-119.
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