饱和土中桩对瑞利波的动力响应
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摘要
基于Boit饱和多孔介质理论,采用文克勒地基梁模型,研究了表面透水的饱和土介质中桩顶自由的情况下桩对瑞利波的横向响应。计算了:①软土和硬土情况下不同深度桩的响应;②饱和土的孔隙率对桩的响应之影响;③土介质相对刚度对桩响应的影响;④fc-z空间桩响应的分布。结果表明,饱和土介质中桩对瑞利波的横向响应受波的频率、土介质性质、桩—土刚度比等因素的影响。整体来看,瑞利波对桩的横向影响自上而下大致呈衰减趋势,在地表处其影响最大;瑞利波对桩的影响深度随频率的降低而扩大;桩和土之间的水平相对位移幅度与土的孔隙率、刚度比均呈正相关关系;同频率下,相对软土地基来说硬土地基中的桩受瑞利波的影响较深。计算结果对工程抗震设计具有实用价值。
On the basis of Boit′s theory of saturated porous medium, we use Winkler foundation beam model to study the response of the pile to Rayleigh wave when the top of the pile is free in non-watertight saturated soil on the surface. The computations include: the response of the pile in both soft soil and hard soil at different depths, the pile response influenced by porosity, the influence of relative rigidity, the distribution of pile response in fc-z space. The Results indicate that the horizontal response of pile to Rayleigh wave is affected by frequency, character of soil medium, pile-soil rigidity ratio. On the whole, the influence of Rayleigh wave on the horizontal movement of pile shows a descending tendency from top to bottom, and the maximum value appears on the surface; the influenced depth of the pile by Rayleigh wave extends with decreasing frequency; the relative horizontal displacement between pile and soil assumes positive correlativity with porosity and relativity rigidity ratio; under the same frequency, the Rayleigh wave influence on pile in the hard soil is deeper than that in soft soil. These results are useful for engineering anti-seismic design.
On the basis of Boit′s theory of saturated porous medium, we use Winkler foundation beam model to study the response of the pile to Rayleigh wave when the top of the pile is free in non-watertight saturated soil on the surface. The computations include: the response of the pile in both soft soil and hard soil at different depths, the pile response influenced by porosity, the influence of relative rigidity, the distribution of pile response in fc-z space. The Results indicate that the horizontal response of pile to Rayleigh wave is affected by frequency, character of soil medium, pile-soil rigidity ratio. On the whole, the influence of Rayleigh wave on the horizontal movement of pile shows a descending tendency from top to bottom, and the maximum value appears on the surface; the influenced depth of the pile by Rayleigh wave extends with decreasing frequency; the relative horizontal displacement between pile and soil assumes positive correlativity with porosity and relativity rigidity ratio; under the same frequency, the Rayleigh wave influence on pile in the hard soil is deeper than that in soft soil. These results are useful for engineering anti-seismic design.
引文
胡昌斌,王奎华,谢康和.2003.考虑桩土耦合作用时弹性支承桩纵向振动特性分析及应用[J].工程力学,20(2):146-154.
胡亚元,王立忠,张忠苗.1997.横观各向同性饱和土的Lamb问题[J].浙江大学学报,7(4):357-362.
胡亚元,王立忠,张忠苗.1998.横观各向同性饱和土中实用波动方程[J].振动工程学报,11(2):170-176.
蒋东旗,王立忠,陈云敏.2003.远场地震引起的单桩横向位移和内力[J].岩土工程学报,25(2):174-178.
李强,王奎华,谢康和.2004.饱和土中端承桩纵向振动特性研究[J].力学学报,36(4):435-442.
王立忠,冯永正,柯翰,等.2001.瑞利波作用下成层地基中单桩横向振动分析[J].振动工程学报,14(2):205-210.
吴世明.1997.土介质中的波[M].北京:科学出版社,102-104.
Biot MA.1956.Theory of propagation of elastic waves in a fluid-saturated porous solid I.low-frequency range[J].J Acoust Society America,28(2):168-178.
Biot MA.1962.Mechanics of deformation and acoustic propagation in porous mediua[J].J Appl Phys,33(4):1482-1498.
Gazetas G,Dobry R.1984.Single radiation damping model for pile and footings[J].Mech.ASCE,110:937-956.
Makris N.1994.Soil-pile interaction during the passage of Rayleigh waves:an analytical solution[J].Earthquake Eng Struct Dyn,23:153-163.
Militano G,Rajapakse R K N D.1999.Dynamic response of a pile in a multi-layered soil to transient torsional and axial loading[J].Geotechnique49(1):91-109.
Mylonakis G,Gazetas G.2002.Kinematic pile response to vertical P-wave seismic excitation[J].J Geotech Geoenv Engng,128(10):860-867
Nogami T,Novak M.1976.Soil-pile interaction in vertical vibration[J].Earth Engng Stuct Dyn,4:277-293.
Zeng X,Rajapakse R K N D.1999.Dynamic axial load transfer from elastic bar to poroelastic medium[J].J Engng Mech,125(9):1048-1055.
胡亚元,王立忠,张忠苗.1997.横观各向同性饱和土的Lamb问题[J].浙江大学学报,7(4):357-362.
胡亚元,王立忠,张忠苗.1998.横观各向同性饱和土中实用波动方程[J].振动工程学报,11(2):170-176.
蒋东旗,王立忠,陈云敏.2003.远场地震引起的单桩横向位移和内力[J].岩土工程学报,25(2):174-178.
李强,王奎华,谢康和.2004.饱和土中端承桩纵向振动特性研究[J].力学学报,36(4):435-442.
王立忠,冯永正,柯翰,等.2001.瑞利波作用下成层地基中单桩横向振动分析[J].振动工程学报,14(2):205-210.
吴世明.1997.土介质中的波[M].北京:科学出版社,102-104.
Biot MA.1956.Theory of propagation of elastic waves in a fluid-saturated porous solid I.low-frequency range[J].J Acoust Society America,28(2):168-178.
Biot MA.1962.Mechanics of deformation and acoustic propagation in porous mediua[J].J Appl Phys,33(4):1482-1498.
Gazetas G,Dobry R.1984.Single radiation damping model for pile and footings[J].Mech.ASCE,110:937-956.
Makris N.1994.Soil-pile interaction during the passage of Rayleigh waves:an analytical solution[J].Earthquake Eng Struct Dyn,23:153-163.
Militano G,Rajapakse R K N D.1999.Dynamic response of a pile in a multi-layered soil to transient torsional and axial loading[J].Geotechnique49(1):91-109.
Mylonakis G,Gazetas G.2002.Kinematic pile response to vertical P-wave seismic excitation[J].J Geotech Geoenv Engng,128(10):860-867
Nogami T,Novak M.1976.Soil-pile interaction in vertical vibration[J].Earth Engng Stuct Dyn,4:277-293.
Zeng X,Rajapakse R K N D.1999.Dynamic axial load transfer from elastic bar to poroelastic medium[J].J Engng Mech,125(9):1048-1055.
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