砼芯水泥土搅拌桩复合地基工作特性分析

Analysis of work characteristics of concrete-cored DCM pile composite foundation

针对砼芯水泥土搅拌桩复合地基工作特性较为复杂的问题,基于砼芯水泥土搅拌桩(DCM)复合地基载荷板试验,采用弹塑性有限元方法,讨论不同芯长比和含芯率条件下砼芯水泥土搅拌桩复合地基的荷载传递、承载力和沉降变化规律.计算结果表明:随着芯长比的增加,越来越多的上部荷载集中至砼芯,同时桩周土体上的竖向应力减小;水泥土搅拌桩外壳在上部与桩周土和砼芯共同承担竖向荷载,随着桩体入土深度的增加变为负责传递砼芯与桩周土之间的剪应力;砼芯长度控制了桩土侧摩阻力的发挥长度,而且使得桩土侧摩阻力沿深度均匀发挥;芯长比和含芯率对于砼芯水泥土搅拌桩复合地基承载力的影响是相互的,选择合适的芯长比和含芯率组合,能最大限度地发挥砼芯水泥土搅拌桩桩复合地基的承载力.

Aiming at the complex working characteristics of Concrete-cored deep cement mixing （DCM） pile composite foundation based on the results of plate load tests on concrete-cored DCM pile composite founda- tion, the elastoplastic finite element method was used to analyze the load transfer mechanism, settlement and bearing capacity characteristics of concrete-cored DCM pile composite foundation with different core- column length ratio and core ratio. The calculation results show that, with the increase of core-column length ratio and core ratio, the vertical stress on precast core pile and surrounding soil increase and de- crease, respectively. The overburden load is shared by precast core pile, DCM column socket and sur- rounding soil. The main role played by DCM column socket in the composite pile system is to transfer shear stress from precast core piles to surrounding soil. The depth of skin friction between surrounding soil and DCM column socket is controlled by the＇length of precast core pile. The distribution of skin fric- tion between surrounding soil and DCM column socket is uniform along depth with the effect of precast core pile. Both the core-column length ratio and the core ratio play an important effect on the bearing ca- pacity of concrete-cored DCM pile composite foundation. The bearing capacity of concrete-cored DCM pile composite foundation can be improved by the suitable combination of core-column length ratio and core ratio.