劲性搅拌桩复合地基承载性能静动力分析

以有限元程序ANSYS为工具，建立三维有限元模型，分析了劲性搅拌桩在竖向荷载下的桩身应力、位移和不同芯桩长度和截面含芯率的极限承载力以及劲性搅拌桩和混凝土桩单桩极限承载力的差异。对不同地震作用下劲性搅拌桩的桩-土-上部结构的相互作用进行了时程分析，并与桩基础做了对比，进而对影响劲性搅拌桩复合地基抗震性能的主要因素进行了研究。结果表明，劲性搅拌桩所承担的荷载主要由侧摩阻力分担；劲性搅拌桩存在一个最佳内外芯桩长度比和最优截面含芯率。在相同地震作用下，劲性搅拌桩单桩的最大弯矩和剪力均小于桩基础；单桩的最大弯矩出现在距桩顶（0.2～0.4）L 处；截面含芯率对劲性搅拌桩弯矩和剪力的影响程度较芯桩长度大，水泥土模量对之影响甚微。

Static and dynamic analysis of bearing capacity of composite foundation of concrete core mixing piles

The axial stress and axial displacement distribution curves of the concrete core mixing single pile are researched by ANSYS software; and the differences of the single pile ultimate capacity of concrete core mixing pile between different concrete core pile length and area replacing ratio are analyzed; then the single pile ultimate capacity of concrete core mixing pile is compared with that of concrete pile. The different seismic response analyses in time domain is performed with 3-D finite element method, taking into account of the interaction among pile-soil-superstructure. The differences between composite foundation of concrete core mixing pile and pile foundation in seismic response are analyzed. Some parameters influencing the aseismic behavior of composite foundation of concrete core mixing pile are studied. The results show that the core pile shaft friction undertakes the mass of vertical load of the pile; and it is found that there are an optimum core pile length and area replacing ratio for the concrete core mixing pile. The maximum bending moment and shear force of concrete core mixing pile are greater than pile foundation’s under the same seismic response. The maximum moment of concrete core mixing pile lies in the (0.2-0.4) L; the effect degree of area replacing ratio on bending moment and shear is greater than concrete core pile length’s effect; the effect of elastic module of cement-soil is slight.