在现场试验的基础上，利用FLAC3D建立数值模拟模型，改变水泥土搅拌桩复合地基的桩长，分别计算4种桩长复合地基的承载力、沉降以及桩、土应力，分析桩端进入硬土层的长度变化对复合地基承载性能的影响。结果表明，水泥土桩进入硬土层的长度对复合地基的承载力和沉降影响不显著，桩端进入硬土层深度范围宜为1～5倍桩径。

 Numerical simulation model were established with FLAC3D to calculate the bearing capacity, the settlement of composite foundation with different lengths of pile and the stress of pile and soil. The lengths of pile entered in the hard soil which have influence on the bearing behavior of composite foundation have been analyzed. The results show that the length of cement-soil pile entered in the hard soil has no obvious influence on the bearing capacity and the settlement of composite foundation. The length of the pile entered in the hard soil should be taken from two to five times pile diameter.