非均质土体中群桩纵向振动的内外域模型解

Solution of vertical vibration of pile groups for inner and outer regions model of heterogeneous soil

考虑土体沿径向的非均质特性,将桩周土体分为内域土和外域土两部分。基于Novak薄层法分别求解了内域土和外域土的竖向振动。考虑内域土和外域土接触面的连续性条件,求得了桩土竖向动力相互作用的等效Winkler弹簧-阻尼器模型的刚度系数和阻尼系数。根据土体竖向位移衰减函数和桩桩竖向动力相互作用因子的定义,考察了非均质土体的竖向位移衰减函数和非均质土体中桩桩竖向动力相互作用因子,进而研究了非均质土中群桩的竖向动力阻抗。研究表明,非均质土体的竖向位移衰减函数和非均质土中群桩的竖向振动可以退化到均质土的情形,忽略桩周土体沿径向的非均质特性将导致土体竖向位移衰减函数偏小而群桩竖向动力阻抗偏大,桩周土体内外域剪切模量比和桩间距等对群桩竖向振动有较大的影响。

Considering the heterogeneous characteristics along the radial direction of the soil around the pile,the soil is divided into two regions：the inner region and the outer region.The vertical vibrations of the inner region soil and outer region soil are solved based on the Novak′s layer method,and the stiffness and damping coefficients of equivalent Winkler spring-damper model of the dynamic interaction of pile-soil is obtained by considering the inner region and outer region contact surface continuity conditions.According to the definitions of vertical displacement attenuation function and pile-pile vertical dynamic interaction factor,the vertical displacement attenuation function of heterogeneous soil and pile-pile vertical dynamic interaction factor are investigated,and the vertical dynamic impedance of pile groups in heterogeneous soil is also analyzed.The results indicate that the vertical displacement attenuation function of heterogeneous soil and the vertical vibration of pile groups in heterogeneous soil can be degenerated into the case of homologous soil;ignoring the heterogeneity of the soil around the pile along the radial direction will result in a smaller vertical displacement attenuation function of soil and a smaller vertical dynamic impedance of pile groups.The shear modulus ratio of inner region and outer region soil,the pile spacing distance have great effects on the vertical vibration of pile groups in heterogeneous soil.