重力式挡土结构地震永久位移分析
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摘要
地震往往导致重力式挡土墙的永久性位移,为了分析地震动以及墙土体系本身属性对位移的影响,基于Raffnsson、Wu和Prakash方法的基本思路,引入考虑填土粘聚力的地震土压力解析解,建立了累积位移的计算模型。建模中考虑墙体滑移和转动两种位移模式相耦合、地基土动力非线性和填土粘聚性。对算例挡墙输入18条合成加速度记录,得到不同地基、不同填土条件下的位移累积时程和最终永久位移。分析结果表明,永久位移与地震动峰值加速度和峰值速度近似呈线性关系,与地震烈度近似呈指数关系;地基土越软弱,永久位移越大,并且转动位移越显著,这种效应与地震动强烈程度有关,地震动越强烈,影响越大;增加填土摩擦角和粘聚力,会降低地震永久位移;增加填土的坡角将加大永久位移,并且地震烈度越高,填土坡角的影响越显著。
During earthquakes,gravity retaining walls tend to experience permanent displacement,which is determined by ground motion and soil-wall system properties. Based on the Raffnsson,Wu and Prakash's framework and the theory on seismic earth pressure of cohesive backfill,a model was established to compute the cumulative displacement. A coupling mode of sliding and rocking was considered,and the dynamic nonlinearity of foundation soil and the cohesion of backfill soil were simulated. 18 synthetic acceleration time histories were inputted into the model to obtain the cumulative displacement time histories and the final permanent displacements under various conditions of foundation soil and backfill. The results show that there is an approximately linear relationship between the permanent displacement and the ground motion amplitude. The displacement mounts up at an exponential speed with earthquake intensity increasing. The softer foundation soil,the larger the displacement is,and as well the more significant the rotation is. This effect will be enhanced when the earthquake intensity increases. The increase of friction angle or cohesion in backfill will reduce the permanent displacement. The raise of backfill slope angle will enlarge the displacement,and the increase speed will be higher when earthquake is more intensive.
During earthquakes,gravity retaining walls tend to experience permanent displacement,which is determined by ground motion and soil-wall system properties. Based on the Raffnsson,Wu and Prakash's framework and the theory on seismic earth pressure of cohesive backfill,a model was established to compute the cumulative displacement. A coupling mode of sliding and rocking was considered,and the dynamic nonlinearity of foundation soil and the cohesion of backfill soil were simulated. 18 synthetic acceleration time histories were inputted into the model to obtain the cumulative displacement time histories and the final permanent displacements under various conditions of foundation soil and backfill. The results show that there is an approximately linear relationship between the permanent displacement and the ground motion amplitude. The displacement mounts up at an exponential speed with earthquake intensity increasing. The softer foundation soil,the larger the displacement is,and as well the more significant the rotation is. This effect will be enhanced when the earthquake intensity increases. The increase of friction angle or cohesion in backfill will reduce the permanent displacement. The raise of backfill slope angle will enlarge the displacement,and the increase speed will be higher when earthquake is more intensive.
引文
[1]刘恢先.唐山大地震震害[M].北京:地震出版社,1986.
[2]中国赴日地震考察团.日本阪神大地震考察[M].北京:地震出版社,1995.
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[4]HUANG C C.Seismic displacements of soil retaining walls situated on slope[J].Journal of Geotechnical and Geoenvironmental Engineering,ASCE,2005,131(9):1108-1117.
[5]ZENG X.Seismic response of gravity quay walls I:centrifuge modeling[J].Journal of Geotechnical and Geoenvironmental Engineering,ASCE,1998,124(5):0406-0417.
[6]TODOROVSKI L I.An experimental study on the kinetics of a free standing retaining wall under seismic excitation[D].Texas:Aand MUniver-sity,1999.
[7]杨明,吴德伦,言志信.加筋土挡墙抗震分析中的屈服加速度[J].岩石力学与工程学报,2002,21(5):728-731.
[8]陈学良,陶夏新,陈宪麦,等.重力挡土墙地震反应研究评述[J].自然灾害学报,2006,15(3):139-146.
[9]RAFNSSON E A,PRAKASHS.Stiffness and damping parameters for dynamic analysis of retaining walls[C].Proceeding of2ndInternational Con-ference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics.St Louis:[s.n].,1991:1943-1952.
[10]WUY W,PRAKASHS.Seismic displacement of rigid retaining walls on submergence[C/OL].Proceeding of12thWorld Conference on Earth-quake Engineering.Philippines,2000:0562.
[11]WU Y W.Displacement-based analysis and design of rigid retaining walls during earthquakes[D].Missouri:University of Missouri-Rolla,2000.
[12]SEED HB,IDRISS I M.Soil moduli and damping factors for dynamic response analysis[R].Berkeley:Earthquake Engineering Research Cen-ter,University of California,Berkeley,1970:1-40.
[13]陈学良,陶夏新.粘性土挡土墙地震土压力解析解[M].南京:东南大学出版社,2002:69-77.
[14]陈宪麦.挡土结构抗震设计中两个重要问题的研究[D].哈尔滨:中国地震局工程力学研究所,2003.
[2]中国赴日地震考察团.日本阪神大地震考察[M].北京:地震出版社,1995.
[3]HUANG C C,CHENY H.Seismic stability of soil retaining walls situated on slope[J].Journal of Geotechnical and Geoenvironmental Engineer-ing,ASCE,2004,130(1):45-57.
[4]HUANG C C.Seismic displacements of soil retaining walls situated on slope[J].Journal of Geotechnical and Geoenvironmental Engineering,ASCE,2005,131(9):1108-1117.
[5]ZENG X.Seismic response of gravity quay walls I:centrifuge modeling[J].Journal of Geotechnical and Geoenvironmental Engineering,ASCE,1998,124(5):0406-0417.
[6]TODOROVSKI L I.An experimental study on the kinetics of a free standing retaining wall under seismic excitation[D].Texas:Aand MUniver-sity,1999.
[7]杨明,吴德伦,言志信.加筋土挡墙抗震分析中的屈服加速度[J].岩石力学与工程学报,2002,21(5):728-731.
[8]陈学良,陶夏新,陈宪麦,等.重力挡土墙地震反应研究评述[J].自然灾害学报,2006,15(3):139-146.
[9]RAFNSSON E A,PRAKASHS.Stiffness and damping parameters for dynamic analysis of retaining walls[C].Proceeding of2ndInternational Con-ference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics.St Louis:[s.n].,1991:1943-1952.
[10]WUY W,PRAKASHS.Seismic displacement of rigid retaining walls on submergence[C/OL].Proceeding of12thWorld Conference on Earth-quake Engineering.Philippines,2000:0562.
[11]WU Y W.Displacement-based analysis and design of rigid retaining walls during earthquakes[D].Missouri:University of Missouri-Rolla,2000.
[12]SEED HB,IDRISS I M.Soil moduli and damping factors for dynamic response analysis[R].Berkeley:Earthquake Engineering Research Cen-ter,University of California,Berkeley,1970:1-40.
[13]陈学良,陶夏新.粘性土挡土墙地震土压力解析解[M].南京:东南大学出版社,2002:69-77.
[14]陈宪麦.挡土结构抗震设计中两个重要问题的研究[D].哈尔滨:中国地震局工程力学研究所,2003.
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