考虑三维波动的饱和土中管桩群桩的水平振动研究

Horizontal vibration of pipe pile groups in saturated soil considering three-dimensional wave effects

考虑桩周饱和土和桩芯饱和土的三维波动效应研究了饱和土中管桩群桩的水平振动,得到了管桩群桩的水平动力阻抗。将桩周土和桩芯土视为两相饱和土,并利用多孔介质理论来描述其力学特性。运用数学物理手段求得了桩周饱和土和桩芯饱和土的水平动力阻抗。运用波的传播理论和叠加原理,同时考虑边界条件和三角函数的正交性,求得了管桩群桩中任一根管桩的水平作用力。考虑刚性承台处管桩桩顶位移协调条件和桩顶水平作用力平衡条件,得到了饱和土中管桩群桩的水平动力阻抗。以2×2管桩群桩为例分析和讨论了有关物理参量对饱和土中管桩群桩水平振动特性的影响。研究结果表明:实芯群桩与管桩群桩的水平动力阻抗都存在一定的差异,频率较小时需要考虑桩芯饱和土与桩周饱和土性质的差异对管桩水平动力阻抗的影响,管桩长径比和管桩壁厚对饱和土中管桩群桩水平振动的影响较大,在实际工程设计中需要重点考虑桩身尺寸。

The horizontal vibration of the pipe pile groups in saturated soil is studied by considering three-dimensional wave effects on the saturated soil, and the horizontal dynamic impedance of pipe pile groups is also obtained. The soil around pile and pile core soil are considered as two-phase saturated soil, and the mechanical property of the saturated soil is described by the theory of porous medium. The horizontal dynamic impedances of the saturated soil around pile and in pile core are obtained by using the mathematical physics means. Using the wave spread theory and superposition principle, the horizontal force of any pipe pile is obtained by considering boundary conditions and orthogonality of trigonometric functions. The horizontal dynamic impedances of pipe pile groups in saturated soil is obtained by considering the displacement compatibility conditions and horizontal force equilibrium conditions at pipe pile top at rigid cap. The influences of physical parameters on the dynamic characteristics of pipe pile groups in saturated soil are analyzed and discussed by using 2×2 pipe pile groups as an example. The result indicates that there are some differences between the horizontal dynamic impedances of the solid core pile groups and the pipe pile groups. It needs to consider the influence of the difference between the saturated soil around pile and in pile core on the dynamic impedance of pipe pile groups in saturated soil. Length to diameter ratio and wall thickness of pipe pile have great effect on the horizontal vibration of pipe pile groups in saturated soil, showing that the size of pipe pile should be focused in the actual engineering design.