摘要
采用边界元结合有限元法研究了非饱和地基群桩基础动力阻抗。根据梁模型建立桩体动力控制方程,结合有限元方法建立群桩基础数值模型;基于非饱和多孔介质动力控制方程组,采用加权残余法和拉普拉斯变换,推导非饱和地基边界元法控制方程,根据伴随矩阵性质推导其Green函数基本解答。基于桩体和地基土接触面作用力平衡条件和位移相容原理,建立非饱和地基边界元模型和群桩基础有限元模型的耦合数值模型;研究土体饱和度、桩体间距、长度、数目和地基分层等参数对群桩基础动力阻抗的影响。研究发现:地基饱和度增加可降低群桩基础刚度系数;荷载频率较低时增大饱和度可减小群桩基础阻尼系数。增加桩基数目和地基饱和度可增大桩基与地基土相互作用。下卧基岩分层地基可提高桩基与土体的相互作用,且对群桩水平阻抗影响显著。
This study analyzes the dynamic impedances of pile group foundations in unsaturated ground using a numerical approach that couples the boundary element method(BEM)and finite element method(FEM).The governing equations for the pile element are derived using beam equations,establishing a numerical model of the pile group using FEM.The governing equations for the unsaturated ground in the BEM are derived using the weighted residual method and Laplacian transform,based on the governing equations of the unsaturated poroviscoelastic medium.The fundamental Green solutions for the unsaturated medium are obtained using the properties of the adjoint matrix.The coupled numerical model,comprising the BEM model for the unsaturated ground and the FEM model for the pile group foundation,is obtained from force balance conditions and displacement compatibility at the interfaces between the piles and soil.The study investigates the effects of soil saturation degree,pile length,pile spacing,pile number,and ground properties on the dynamic impedances of group piles.The research findings indicate that an increase in saturation degree reduces the stiffness of the pile group foundation and the damping coefficient at low frequencies.Additionally,both an increase in saturation degree and an increase in pile number enhance the interaction between the pile and soil.The presence of an underlying bedrock in layered ground increases the pile-soil interaction and significantly influences the horizontal impedance of pile group.
作者
李绍毅
LI Shao-yi(School of Civil Engineering and Architecture,Jishou University,Zhangjiajie,Hunan 427000,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2024年第3期895-907,共13页
Rock and Soil Mechanics
关键词
非饱和介质
群桩基础
动力阻抗
有限元+边界元方法
分层地基
unsaturated medium
group piles foundation
dynamic impedance
coupled FE+BE method
layered ground
