海底管线周围海床的地震液化分析
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摘要
地震荷载作用下海床液化是海底管线失稳的主要原因之一.本文建立了地震荷载作用下海底管线周围海床液化的有限元模型,采用土工静力-动力液压三轴-扭剪多功能剪切仪,将不排水循环扭剪试验条件下得到的孔隙水压力增长模式引入到二维动力固结方程中,基于有限元方法对推广的固结方程进行数值求解,得到了地震荷载作用下海床中累积孔隙水压力的发展过程与变化规律.通过变动参数计算了海床土性参数和管线几何尺寸对由地震所引起的管线周围海床中累积孔隙水压力分布的影响,进一步对管线周围海床的液化势进行了评判.
The liquefaction of seabed under seismic loading is one of the main reasons that govern the overall stability of submarine pipeline.In this paper,a FEM numerical analysis method on liquefaction around a buried pipeline in sandy seabed under seismic loading is presented.The advanced soil static and dynamic universal triaxial and torsional shear apparatus is employed to perform cyclic torsional shear tests subjected to cyclic loading,and the mode of dynamic increase of pore pressure under undrained conditions gained from tests is incorporated with two-dimensional dynamic consolidation equation and a numerical procedure based on FEM is developed to assess the accumulative pore pressure.By numerical computations,the accumulation process of pore pressure and liquefaction potential of seabed soil during seismic loading can be evaluated.Based on the numerical model presented in this paper,the effects of soil characteristic parameters and pipeline geometry on the seismic-induced accumulative pore pressure around submarine pipeline and along the depth of seabed are studied in detail.
The liquefaction of seabed under seismic loading is one of the main reasons that govern the overall stability of submarine pipeline.In this paper,a FEM numerical analysis method on liquefaction around a buried pipeline in sandy seabed under seismic loading is presented.The advanced soil static and dynamic universal triaxial and torsional shear apparatus is employed to perform cyclic torsional shear tests subjected to cyclic loading,and the mode of dynamic increase of pore pressure under undrained conditions gained from tests is incorporated with two-dimensional dynamic consolidation equation and a numerical procedure based on FEM is developed to assess the accumulative pore pressure.By numerical computations,the accumulation process of pore pressure and liquefaction potential of seabed soil during seismic loading can be evaluated.Based on the numerical model presented in this paper,the effects of soil characteristic parameters and pipeline geometry on the seismic-induced accumulative pore pressure around submarine pipeline and along the depth of seabed are studied in detail.
引文
[1]SEED R B,CETIN K O,MOSS R E S,et al.Recent advances in soil liquefaction Engineering:A unified and consistent framework[R].White Paper for Keynote Presentation,26th Annual ASCE Los Angeles Geotechnical Spring Seminar. California:Long Beach,2003.
[2]SEED H B,MARTIN P P,LYSMER J.Pore-water pressure changes during soil liquefaction[J].Journal of the Geotechnical Engineering Division,ASCE,1976,102(GT2):323-346.
[3]BOOKER J R,RAHMAN M S,SEED H B.GADFLFA-A computer program for the analysis of pore pressure generation and dissipation during cycle or earthquake loading[R].Report No UCB/EERC-76/24.Berkley:University of California, 1976.
[4]栾茂田,钱令希.层状饱和砂土振动孔隙水压力扩散与消散简化解法[J].大连理工大学学报,1995,35(2):216-221. LUAN Mao-tian,QIAN Ling-xi.Simplified procedure for estimating shaking-induced pore-water pressure dissipation of layered saturated sands[J].Journal of Dalian University of technology,1995,35(2):216-221.(in Chinese)
[5]徐志英.地震期孔隙水压力变化估算方法[J].水利学报,1981(4):68-73. XU Zhi-ying.An evaluation method of pore pressure during earthquake[J].Journal of Hydraulic Engineering,1981(4):68- 73.(in Chinese)
[6]栾茂田,郭莹,李木国,等.土工静力-动力液压三轴-扭转多功能剪切仪开发及其应用[J].大连理工大学学报, 2003,43(5):670-675. LUAN Mao-tian,GUO Ying,LI Mu-guo,et al.Development and application of soil static and dynamic universal triaxial and torsional shear apparatus[J].Journal of Dalian University of technology,2003,43(5):670-675.(in Chinese)
[7]BIOT M A.General theory of three-dimensional consolidation[J].Journal of Applied Physics,1941,12(2):155-164.
[8]ZEN K,YAMAZAKI H.Mechanism of wave-induced liquefaction and densification in seabed[J].Soils and Foundations, Japanese Society of Soil Mechanic and Foundation Engineering,1990,30(4):90-104.
[2]SEED H B,MARTIN P P,LYSMER J.Pore-water pressure changes during soil liquefaction[J].Journal of the Geotechnical Engineering Division,ASCE,1976,102(GT2):323-346.
[3]BOOKER J R,RAHMAN M S,SEED H B.GADFLFA-A computer program for the analysis of pore pressure generation and dissipation during cycle or earthquake loading[R].Report No UCB/EERC-76/24.Berkley:University of California, 1976.
[4]栾茂田,钱令希.层状饱和砂土振动孔隙水压力扩散与消散简化解法[J].大连理工大学学报,1995,35(2):216-221. LUAN Mao-tian,QIAN Ling-xi.Simplified procedure for estimating shaking-induced pore-water pressure dissipation of layered saturated sands[J].Journal of Dalian University of technology,1995,35(2):216-221.(in Chinese)
[5]徐志英.地震期孔隙水压力变化估算方法[J].水利学报,1981(4):68-73. XU Zhi-ying.An evaluation method of pore pressure during earthquake[J].Journal of Hydraulic Engineering,1981(4):68- 73.(in Chinese)
[6]栾茂田,郭莹,李木国,等.土工静力-动力液压三轴-扭转多功能剪切仪开发及其应用[J].大连理工大学学报, 2003,43(5):670-675. LUAN Mao-tian,GUO Ying,LI Mu-guo,et al.Development and application of soil static and dynamic universal triaxial and torsional shear apparatus[J].Journal of Dalian University of technology,2003,43(5):670-675.(in Chinese)
[7]BIOT M A.General theory of three-dimensional consolidation[J].Journal of Applied Physics,1941,12(2):155-164.
[8]ZEN K,YAMAZAKI H.Mechanism of wave-induced liquefaction and densification in seabed[J].Soils and Foundations, Japanese Society of Soil Mechanic and Foundation Engineering,1990,30(4):90-104.
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