变附加应力条件下组合桩复合地基固结理论研究

STUDY ON CONSOLIDATION THEORY OF COMBINED COMPOSITE FOUNDATION UNDER VARIABLE ADDITIONAL STRESS

  • 摘要: 针对组合碎石桩–不排水桩复合地基固结问题,考虑碎石桩径向和竖向组合渗流、附加应力随时间和深度变化等因素对复合地基固结速率的影响,建立组合桩复合地基固结计算模型,采用解析法推导了变附加应力条件下组合桩复合地基固结解析解。进行固结度解退化研究,与已有解对比分析,验证了此解的正确性。通过算例计算,绘制了不同因素影响下复合地基固结度变化曲线。结果表明:增加地基顶部与底部的附加应力比值、碎石桩与土体的径向渗透系数比值,复合地基固结速率加快;忽略碎石桩的径向渗流,会高估复合地基的固结速率;减小桩径比可显著提高复合地基固结速率;增加外围不排水桩的置换率,对复合地基固结速率的加快效果不明显。

     

    Abstract: For the consolidation problem of combined stone columns and impervious piles composite foundation, the influences of radial and vertical flows within stone columns and additional stress varied with time and depth on the consolidation rate of composite foundation are considered, the consolidation calculation model of composite foundation is established, and the analytical solution of composite foundation under time and depth dependent additional stress is derived by using an analytical method. The degradation of the consolidation degree solution is studied, and the correctness of the solution is verified by comparing with existing solutions. The curve of consolidation degree of composite foundation under the influence of different factors is drawn by example analysis. The results show that consolidation accelerates if increasing the ratio of additional stress between top and bottom of foundation accelerates consolidation, or increasing the ratio of radial permeability coefficient between stone columns and soil. Ignoring the radial flow in the stone columns will overestimate the consolidation rate of composite foundation. The consolidation rate of composite foundation can be significantly increased by decreasing the radius ratio of element model to stone columns. Increasing the replacement rate of impervious piles in the exterior has no obvious effect on the accelerating the consolidation rate of composite foundation.

     

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