地震荷载作用下海底管线周围砂质海床的稳定性分析
|
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。建立地震荷载作用下海底管线周围砂质海床液化问题的有限元模型,利用先进的土工静力–动力液压三轴–扭剪多功能剪切仪,将在不排水循环扭剪试验条件下得到的孔隙水压力增长模式作为考虑地震循环作用所引起的孔隙水压力源项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,得到地震荷载作用下砂质海床中累积孔隙水压力的发展过程与变化规律。通过变动参数计算研究砂质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,进一步对管线周围砂质海床的液化势进行评判。通过计算分析发现,土的渗透系数对由地震所引起的管线周围砂质海床中的累积孔隙水压力比具有显著影响,而管线半径只影响管线周围海床的累积孔隙水压力比分布,在离开管线一定距离之外,其影响可以忽略。
The liquefaction of seabed under seismic load is one of the main reasons that govern the global stability of submarine pipeline.A finite element numerical analysis method for liquefaction around a buried pipeline in sandy seabed under seismic load is presented.The advanced soil static and dynamic universal triaxial and torsional shear apparatus is employed to perform torsional shear tests subjected to cyclic loading.The mode of dynamic increase of pore water 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 water pressure.By numerical computation,the accumulation process of pore water pressure and liquefaction potential of sandy seabed soil under seismic load can be evaluated.Based on the presented numerical model,the effects of sandy soil characteristic parameters and pipeline geometry on the seismic-induced accumulative pore water pressure around submarine pipeline and along the depth of seabed are studied.By the computation and analysisi,t is found that the effects of soil permeability coefficient on the seismic-induced accumulative pore water pressure ratios of sandy seabed around the pipeline are remarkable.Otherwise,the radius of pipeline only influence the accumulative pore water pressure ratios of sandy seabed nearby the pipeline;and the effects of pipeline can be neglected in the region of seabed far away from the pipeline.
The liquefaction of seabed under seismic load is one of the main reasons that govern the global stability of submarine pipeline.A finite element numerical analysis method for liquefaction around a buried pipeline in sandy seabed under seismic load is presented.The advanced soil static and dynamic universal triaxial and torsional shear apparatus is employed to perform torsional shear tests subjected to cyclic loading.The mode of dynamic increase of pore water 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 water pressure.By numerical computation,the accumulation process of pore water pressure and liquefaction potential of sandy seabed soil under seismic load can be evaluated.Based on the presented numerical model,the effects of sandy soil characteristic parameters and pipeline geometry on the seismic-induced accumulative pore water pressure around submarine pipeline and along the depth of seabed are studied.By the computation and analysisi,t is found that the effects of soil permeability coefficient on the seismic-induced accumulative pore water pressure ratios of sandy seabed around the pipeline are remarkable.Otherwise,the radius of pipeline only influence the accumulative pore water pressure ratios of sandy seabed nearby the pipeline;and the effects of pipeline can be neglected in the region of seabed far away from the pipeline.
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[C]//Proceedings of the 26th Annual ASCE Los Angeles Geotechnical Spring Seminar.Long Beach,USA:[s.n.],2003:1–17.
[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(GT4):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].Berkeley: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 Maotian,QIAN Lingxi.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 Zhiying.An evaluation method of pore water pressure during earthquake[J].Journal of Hydraulic Engineering,1981,(4):68–73.(in Chinese))
[6]LUAN M,QU P,JENG D S,et al.Dynamic response of a porous seabed-pipeline interaction under wave loading:soil-pipeline contact effects and inertial effects[J].Computers and Geotechnics,2008,35(2):173–186.
[7]栾茂田,郭莹,李木国,等.土工静力–动力液压三轴–扭转多功能剪切仪研发及应用[J].大连理工大学学报,2003,43(5):670–675.(LUAN Maotian,GUO Ying,LI Muguo,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))
[8]BIOT M A.General theory of three-dimensional consolidation[J].Journal of Applied Physics,1941,12(2):155–164.
[9]ZHANG X L,LUAN M T,GUO Y,et al.Numerical analyses of dynamic response of saturated porous seabed-pipeline interaction under seismic loading[C]//Proceedings of the 3rd Sino-Japan Geotechnical Symposium.Beijing:Science Press,2007:785–792.
[10]郭莹,张小玲,栾茂田,等.初始中主应力系数对密实粉煤灰动模量阻尼比影响的试验研究[J].岩土力学,2008,29(3):591–595.(GUO Ying,ZHANG Xiaoling,LUAN Maotian,et al.Experimental study on effect of initial intermediate principal stress coefficient on dynamic shear modulus and damping ratio of dense fly ash[J].Rock and Soil Mechanics,2008,29(3):591–595.(in Chinese))
[11]徐斌,孔宪京,邹德高,等.饱和砂砾料振动孔压与轴向应变发展模式研究[J].岩土力学,2006,27(6):925–928.(XU Bin,KONG Xianjing,ZOU Degao,et al.Study on dynamic pore water pressure and axial strain in saturated sand-gravel composites[J].Rock and Soil Mechanics,2006,27(6):925–928.(in Chinese))
[12]ZEN K,YAMAZAKI H.Mechanism of wave-induced liquefaction and densification in seabed[J].Soils and Foundations,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(GT4):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].Berkeley: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 Maotian,QIAN Lingxi.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 Zhiying.An evaluation method of pore water pressure during earthquake[J].Journal of Hydraulic Engineering,1981,(4):68–73.(in Chinese))
[6]LUAN M,QU P,JENG D S,et al.Dynamic response of a porous seabed-pipeline interaction under wave loading:soil-pipeline contact effects and inertial effects[J].Computers and Geotechnics,2008,35(2):173–186.
[7]栾茂田,郭莹,李木国,等.土工静力–动力液压三轴–扭转多功能剪切仪研发及应用[J].大连理工大学学报,2003,43(5):670–675.(LUAN Maotian,GUO Ying,LI Muguo,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))
[8]BIOT M A.General theory of three-dimensional consolidation[J].Journal of Applied Physics,1941,12(2):155–164.
[9]ZHANG X L,LUAN M T,GUO Y,et al.Numerical analyses of dynamic response of saturated porous seabed-pipeline interaction under seismic loading[C]//Proceedings of the 3rd Sino-Japan Geotechnical Symposium.Beijing:Science Press,2007:785–792.
[10]郭莹,张小玲,栾茂田,等.初始中主应力系数对密实粉煤灰动模量阻尼比影响的试验研究[J].岩土力学,2008,29(3):591–595.(GUO Ying,ZHANG Xiaoling,LUAN Maotian,et al.Experimental study on effect of initial intermediate principal stress coefficient on dynamic shear modulus and damping ratio of dense fly ash[J].Rock and Soil Mechanics,2008,29(3):591–595.(in Chinese))
[11]徐斌,孔宪京,邹德高,等.饱和砂砾料振动孔压与轴向应变发展模式研究[J].岩土力学,2006,27(6):925–928.(XU Bin,KONG Xianjing,ZOU Degao,et al.Study on dynamic pore water pressure and axial strain in saturated sand-gravel composites[J].Rock and Soil Mechanics,2006,27(6):925–928.(in Chinese))
[12]ZEN K,YAMAZAKI H.Mechanism of wave-induced liquefaction and densification in seabed[J].Soils and Foundations,1990,30(4):90–104.
版权所有：© 2023 中国地质图书馆 中国地质调查局地学文献中心