地震作用下重力式码头地基液化及变形
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摘要
我国现行码头抗震设计规范采用的单水准抗震设计方法,不能反映不同地震烈度时的抗震性能.采用有限差分软件FLAC 3D,对重力式码头的地震响应和地基状况进行了分析计算,研究重力式码头在不同强度地震作用下地基的超孔隙水压力、超孔压比和码头位移,并用国际航运协会码头结构抗震设计指南所规定的性能设计准则进行了评判.计算表明,在强度较小地震作用下,所分析的重力式码头结构和地基的破坏程度较小,不影响结构的正常使用.在较强地震作用下,沉箱底部置换砂超孔压比增幅较小,置换砂并未液化;码头陆侧回填土层超孔压比增幅较大,回填土层在加速度峰值增加到0.2g后,在不同位置发生液化,沉箱水平及竖向位移在加速度峰值出现后急剧增大,最终导致重力式码头结构发生不同程度的破坏.
The single-level seismic design method proposed in current seismic design code of wharf structures can not reflect the seismic performance of structures under different seismic intensities. In this paper,the seismic responses of the gravity wharf and ground under different seismic loading are analyzed by using the finite difference software FLAC 3D,and the excessive pore water pressure and excessive pore pressure ratio of ground as well as the pier displacement are predicted. The performance-based design criteria provided in the Seismic Design Guidelines for Port Structures proposed by associations are adopted to estimate the seismic response of the gravity wharf. The gravity wharf structure and ground subjected to small seismic loading damage slightly according to the analysis. For the same gravity wharf structure and ground subjected to stronger seismic loading,the excessive pore pressure ratio of replacement sand at the bottom of a caisson increases with small magnitude,and the replacement sand is not liquefied; the excessive pore pressure ratio of backfill soil at landside of the wharf structure increases remarkably;after peak acceleration it increases to 0. 2g,the backfill soil in different locations is liquefied; and due to the rapid increase of horizontal and vertical displacements,the caissons show damage to different extents.
The single-level seismic design method proposed in current seismic design code of wharf structures can not reflect the seismic performance of structures under different seismic intensities. In this paper,the seismic responses of the gravity wharf and ground under different seismic loading are analyzed by using the finite difference software FLAC 3D,and the excessive pore water pressure and excessive pore pressure ratio of ground as well as the pier displacement are predicted. The performance-based design criteria provided in the Seismic Design Guidelines for Port Structures proposed by associations are adopted to estimate the seismic response of the gravity wharf. The gravity wharf structure and ground subjected to small seismic loading damage slightly according to the analysis. For the same gravity wharf structure and ground subjected to stronger seismic loading,the excessive pore pressure ratio of replacement sand at the bottom of a caisson increases with small magnitude,and the replacement sand is not liquefied; the excessive pore pressure ratio of backfill soil at landside of the wharf structure increases remarkably;after peak acceleration it increases to 0. 2g,the backfill soil in different locations is liquefied; and due to the rapid increase of horizontal and vertical displacements,the caissons show damage to different extents.
引文
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[2]刘汉龙,井合进,一井康二.大型沉箱式码头岸壁地震反应分析[J].岩土工程学报,1998,20(2):26-30.(LIU Hanlong,IAI S,ICHII K.Seismic response analysis of large-size caisson quay wall[J].Chinese Journal of Geotechnical Engineering,1998,20(2):26-30.(in Chinese))
[3]SEED H B,BOOKER R.Stabilization of potentially liquefied sand deposits using gravel drains[J].Journal of Geotechnical Engineering Div JCED,1976,102(07):1-15.
[4]CASAGRANDE A.Liquefaction and cyclic deformation of sands-A critical review[C]∥The 5thPan-American Conference Soil Mechanics and Foundation Engineering,Buenos Aires,Argentina,1975.
[5]JTS 146-2012,水运工程抗震设计规范[S].(JTS 146-2012,Code of earthquake resistant design for water transport engineering[S].(in Chinese))
[6]日本港湾協会.港湾の施設の技術上の基準·同解說[S].平成19年7月.(Japan Harbour Association.The technical standards for the facilities of the port[S].2007.(in Japanese))
[7]International Navigation Association.Seismic design guidelines for port structures[M].Netherlands:Balkema Publishers,2001.
[8]MARTIN G R,FINN W D L,SEED H B.Fundamentals of liquefaction under cyclic loading[J].Journal of Geotechnical Engineering Div,1975,101(5):423-438.
[9]BYRNE P M,PARK S S.Seismic liquefaction:centrifuge and numerical modeling[C]∥Third International Symposium on FLAC and FLAC3D Numerical Modeling in Geomechanics,Ontario:2003.
[10]GB 50011-2010,建筑抗震设计规范[S].(GB 50011-2010,Code for seismic design of buildings[S].(in Chinese))
[11]贡金鑫.港口结构抗震设计方法的发展(2)[J].水运工程,2012(7):71-76.(GONG Jin-xin.Development of seismic design of harbor structures(2)[J].Port&Waterway Engineering,2012(7):71-76.(in Chinese))
[2]刘汉龙,井合进,一井康二.大型沉箱式码头岸壁地震反应分析[J].岩土工程学报,1998,20(2):26-30.(LIU Hanlong,IAI S,ICHII K.Seismic response analysis of large-size caisson quay wall[J].Chinese Journal of Geotechnical Engineering,1998,20(2):26-30.(in Chinese))
[3]SEED H B,BOOKER R.Stabilization of potentially liquefied sand deposits using gravel drains[J].Journal of Geotechnical Engineering Div JCED,1976,102(07):1-15.
[4]CASAGRANDE A.Liquefaction and cyclic deformation of sands-A critical review[C]∥The 5thPan-American Conference Soil Mechanics and Foundation Engineering,Buenos Aires,Argentina,1975.
[5]JTS 146-2012,水运工程抗震设计规范[S].(JTS 146-2012,Code of earthquake resistant design for water transport engineering[S].(in Chinese))
[6]日本港湾協会.港湾の施設の技術上の基準·同解說[S].平成19年7月.(Japan Harbour Association.The technical standards for the facilities of the port[S].2007.(in Japanese))
[7]International Navigation Association.Seismic design guidelines for port structures[M].Netherlands:Balkema Publishers,2001.
[8]MARTIN G R,FINN W D L,SEED H B.Fundamentals of liquefaction under cyclic loading[J].Journal of Geotechnical Engineering Div,1975,101(5):423-438.
[9]BYRNE P M,PARK S S.Seismic liquefaction:centrifuge and numerical modeling[C]∥Third International Symposium on FLAC and FLAC3D Numerical Modeling in Geomechanics,Ontario:2003.
[10]GB 50011-2010,建筑抗震设计规范[S].(GB 50011-2010,Code for seismic design of buildings[S].(in Chinese))
[11]贡金鑫.港口结构抗震设计方法的发展(2)[J].水运工程,2012(7):71-76.(GONG Jin-xin.Development of seismic design of harbor structures(2)[J].Port&Waterway Engineering,2012(7):71-76.(in Chinese))
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