波浪作用下可液化海床最大液化深度
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摘要
较大的风浪会使海床发生液化,波浪引起的海床液化问题是海岸及近海工程必须考虑的关键问题之一。基于Biot固结理论,同时考虑了振荡孔隙水压力和残余孔隙水压力的液化准则,作者推出了波浪作用下可液化海床最大液化深度的解析表达式。同时分别采用解析表达式和FLAC数值模拟求解了相应的例子,两者得出的液化深度均和例子的基本相等。且从FLAC的结果可看出,加载波浪力时孔隙水压力开始累积,土体有效应力逐渐下降,当有效应力降到零时,海床土层液化,海床土颗粒重组后下沉压实,之后残余孔隙水压力开始消散,土层有效应力逐渐恢复。最后还就不同波高、波长和水深进行了解析解和数值解的对比,两者得出的结果比较吻合,并能较好地反映海床液化深度变化规律。
Large wave will cause liquefaction of seabed,and wave-induced liquefaction of seabed is a key problem of coastal and offshore engineering.Based on the Biot's theory of consolidation,taking account of both the criteria of liquefaction of oscillatory and residual pore pressures,the analytical solution of the maximum depth of porous sandy seabed under wave loading is derived in this study.With the new expression and the FLAC numerical simulation,an example is calculated,and the results are almost the same.The results of FLAC simulation show that the pore water pressure begins to build up and the effective stress of seabed goes down,when the wave force is loaded.When the effective stress reaches zero,the sediment is liquefied.Then the sediment grains are rearranged and compacted.Later,the residual pore pressure is dissipated,and the effective stress comes to rise.At last,the analytical solution and the numerical calculation are compared for various wave heights,wave lengths and water depths,and the outcomes are about the same,reflecting the regularity well of the liquefaction depth of seabed.
Large wave will cause liquefaction of seabed,and wave-induced liquefaction of seabed is a key problem of coastal and offshore engineering.Based on the Biot's theory of consolidation,taking account of both the criteria of liquefaction of oscillatory and residual pore pressures,the analytical solution of the maximum depth of porous sandy seabed under wave loading is derived in this study.With the new expression and the FLAC numerical simulation,an example is calculated,and the results are almost the same.The results of FLAC simulation show that the pore water pressure begins to build up and the effective stress of seabed goes down,when the wave force is loaded.When the effective stress reaches zero,the sediment is liquefied.Then the sediment grains are rearranged and compacted.Later,the residual pore pressure is dissipated,and the effective stress comes to rise.At last,the analytical solution and the numerical calculation are compared for various wave heights,wave lengths and water depths,and the outcomes are about the same,reflecting the regularity well of the liquefaction depth of seabed.
引文
[1]杨琳,蒋学炼,李炎保.波浪引起的海床失稳机理及有关孔隙水压力的讨论[J].海洋技术,2004,23(4):75-80.YANG Lin,JIANG Xuelian,LI Yanbao.The mechanism of seabed instability induced by wave and the discussion about pore pressure[J].OceanTechnology,2004,23(4):75-80.(in Chinese)
[2]Biot M A.Theory of elasticity and consolidation for a porous anisotropic solid[J].Journal of Applied Physics,1955,26(2):182-185.
[3]Poulos H G.Marine ceotechnics[M].London:Academic Division of Unwin Hyman Ltd,1988.
[4]Zen K,Yamazaki H.Mechanism of wave-induced liquefaction and densification in seabed[J].Soils and Foundations,1990,30(4):90-104.
[5]Jeng D S.Wave-induced seabed instability in front of a breakwater[J].Ocean Engineering,1997,24(10):887-917.
[6]栾茂田,张晨明,王栋,等.波浪作用下海床孔隙水压力发展过程与液化的数值分析[J].水力学报,2004(2):94-100.LUAN Maotian,ZHANG Chenming,WANG Dong,et al.Numerical analysis of residual pore water pressure development and evaluation of lique-faction potential of seabed under wave loading[J].Journal of Hydraulic Engineering,2002,(2):94-100.(in Chinese)
[7]Madsen O S.Wave-induced pore pressures and effective stresses in a porous bed[J].Geotechnique,1978,28(4):377-393.
[8]Jeng D S,Seymour B,Gao F P,et al.Ocean waves propagating over a porous seabed:Residual and oscillatory mechanisms[J].Science in ChinaSeries E:Technological Sciences,2007,50(1):81-89.
[9]韩涛,张庆河,张金凤,等.波浪作用下砂质海床最大液化深度[J].中国港湾建设,2006(2):27-28.HAN Tao,ZHANG Qinghe,ZHANG Jinfeng,et al.Maximum liquefaction depth of sandy seabed under waves[J].China Harbour Engineering,2006,(2):27-28.(in Chinese)
[10]Itasca Consulting Group,Inc.FLAC(Fast Lagrangian Analysis of Continua)User Manuals(Version 5.0).Minneapolis.Minnesota:Itasca Con-sulting Group,Inc,2005.
[11]钟佳玉,郑永来,倪寅.波浪作用下砂质海床孔隙水压力的响应规律实验研究[J].岩土力学,2009,30(10):3188-3193.ZHONG Jiayu,ZHENG Yonglai,NI Yin.Experimental study of response pattern of pore water pressure on sandy seabed under wave action[J].Rock and Soil Mechanics,2009,30(10):3188-3193.(in Chinese)
[12]武伯弢.波浪荷载作用下砂质粉土海床的液化研究[D].上海:同济大学,2009.WU Botao.Study on wave-induced liquefaction in sandy silt seabed[D].Shanghai:Tongji University,2009.(in Chinese)
[13]王根龙,林玮,蔡晓光.基于Finn本构模型的饱和砂土地震液化分析[J].地震工程与工程振动,2010,30(3):178-184.WANG Genlong,LIN Wei,CAI Xiaoguang.Seismic liquefaction analysis of saturated sand soil based on Finn constitutive model[J].Journal ofEarthquake Engineering and Engineering Vibration,2010,30(3):178-184.(in Chinese)
[14]Ishihara K,Yamazaki A.Analysis of wave-induced liquefaction in seabed deposits of sand[J].Soils and Foundations,1984,24(3):85-100.
[2]Biot M A.Theory of elasticity and consolidation for a porous anisotropic solid[J].Journal of Applied Physics,1955,26(2):182-185.
[3]Poulos H G.Marine ceotechnics[M].London:Academic Division of Unwin Hyman Ltd,1988.
[4]Zen K,Yamazaki H.Mechanism of wave-induced liquefaction and densification in seabed[J].Soils and Foundations,1990,30(4):90-104.
[5]Jeng D S.Wave-induced seabed instability in front of a breakwater[J].Ocean Engineering,1997,24(10):887-917.
[6]栾茂田,张晨明,王栋,等.波浪作用下海床孔隙水压力发展过程与液化的数值分析[J].水力学报,2004(2):94-100.LUAN Maotian,ZHANG Chenming,WANG Dong,et al.Numerical analysis of residual pore water pressure development and evaluation of lique-faction potential of seabed under wave loading[J].Journal of Hydraulic Engineering,2002,(2):94-100.(in Chinese)
[7]Madsen O S.Wave-induced pore pressures and effective stresses in a porous bed[J].Geotechnique,1978,28(4):377-393.
[8]Jeng D S,Seymour B,Gao F P,et al.Ocean waves propagating over a porous seabed:Residual and oscillatory mechanisms[J].Science in ChinaSeries E:Technological Sciences,2007,50(1):81-89.
[9]韩涛,张庆河,张金凤,等.波浪作用下砂质海床最大液化深度[J].中国港湾建设,2006(2):27-28.HAN Tao,ZHANG Qinghe,ZHANG Jinfeng,et al.Maximum liquefaction depth of sandy seabed under waves[J].China Harbour Engineering,2006,(2):27-28.(in Chinese)
[10]Itasca Consulting Group,Inc.FLAC(Fast Lagrangian Analysis of Continua)User Manuals(Version 5.0).Minneapolis.Minnesota:Itasca Con-sulting Group,Inc,2005.
[11]钟佳玉,郑永来,倪寅.波浪作用下砂质海床孔隙水压力的响应规律实验研究[J].岩土力学,2009,30(10):3188-3193.ZHONG Jiayu,ZHENG Yonglai,NI Yin.Experimental study of response pattern of pore water pressure on sandy seabed under wave action[J].Rock and Soil Mechanics,2009,30(10):3188-3193.(in Chinese)
[12]武伯弢.波浪荷载作用下砂质粉土海床的液化研究[D].上海:同济大学,2009.WU Botao.Study on wave-induced liquefaction in sandy silt seabed[D].Shanghai:Tongji University,2009.(in Chinese)
[13]王根龙,林玮,蔡晓光.基于Finn本构模型的饱和砂土地震液化分析[J].地震工程与工程振动,2010,30(3):178-184.WANG Genlong,LIN Wei,CAI Xiaoguang.Seismic liquefaction analysis of saturated sand soil based on Finn constitutive model[J].Journal ofEarthquake Engineering and Engineering Vibration,2010,30(3):178-184.(in Chinese)
[14]Ishihara K,Yamazaki A.Analysis of wave-induced liquefaction in seabed deposits of sand[J].Soils and Foundations,1984,24(3):85-100.
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