【摘要】 建立了砂井为中心、砂井影响区边界上零星分布的钉形搅拌(TDM)桩简化为等面积桩环的轴对称固结模型。基于此轴对称固结模型，推导出瞬时荷载下砂井-TDM桩组合型复合地基的固结控制方程并给出相应的定解条件。用分离变量法求解固结方程，获得砂井、砂井周围土体和加固区的平均超静孔隙水压力，进而得到复合地基整体平均固结度。通过与三维有限元固结度计算结果的比较验证了解析解的正确性。利用固结解析解进行参数分析，研究了砂井-TDM桩复合地基的固结特性。结果表明：砂井-TDM桩复合地基的固结速率远大于TDM桩复合地基，它随整个TDM桩的压缩模量、扩大头高度、扩大头以下小直径搅拌桩的压缩模量和直径的增加而增大，扩大头直径的变化对复合地基固结速率的影响较小。更多还原

【Abstract】 An axisymmetric model for consolidation analysis is established, in which a vertical drain locates at its center and some T-shaped deep cement mixing(TDM) columns distributed separately at the circumferential boundary of the influence zone are converted into a column ring with an equal section area. Based on this axisymmetric consolidation model, the consolidation governing equation of the composite ground with vertical drains and TDM columns are derived under instantaneous loading, and the corresponding solution conditions are given. The consolidation equations are solved using the method of separation of variables, the average excess pore water pressures within the vertical drain, the soil around it and the improved zones are obtained, and the overall average degree of consolidation of the composite ground are given. The correctness of the derived solutions is verified by a comparison of the consolidation rate of the combined composite ground with the numerical result from three dimensional finite element method. The parametric analysis is conducted using the proposed solution to investigate the consolidation behavior of the composite ground. The results show that the consolidation rate of the composite ground with vertical drains and TDM columns is much higher than that of TDM column-improved ground. It increases with increasing the constrained modulus of the whole TDM column, the height of the enlarged column cap and the constrained modulus and the diameter of the deep-depth column with smaller diameter bellow the column cap. The change in diameter of the column cap has insignificant effect on the consolidation rate of the composite ground.更多还原