高压旋喷桩技术自20世纪70年代从日本引进我国己有近四十年的历史。当时该技术主要用于软土地基的加固，到了20世纪80年代以后开始用于堤坝防渗。目前，该技术已在全国进行了推广应用，并用于宣大高速、京秦高速等大型工程。它具有安全可靠、适用的土质广、施工噪音小、桩身强度高、固结体形状可控制、料源广阔、价格低廉等特点；因此在建筑物地基加固、深基坑开挖支护与止水、边坡治理、堤坝防渗等方面应用很广。 尹中高速公路软弱黄土地基主要分布在该高速公路穿越山区沟口部位，分布范围与基岩顶面受河流侵蚀程度有关。该区软弱黄土的含水量高，W=24.5~35.1%，W≥WL，天然孔隙比e0=0.68~1.31，压缩性大，强度较低。饱和度大，Sr=81.7%。 IL=1.10，大多呈软塑到流塑状态，工程地质性质差。经过分析与计算，地基最大沉降量为815.5mm，地基土承载力为70~100kPa左右。该软弱地基的填土高度一般为3~7.95m，地基土承载力应在150~200kPa以上，沉降量应小于300mm，稳定安全系数应大于1.1以上。显然该软弱黄土地基不能满足公路工程的要求，且因填土高度较大，土体和地基不稳定，会产生滑动。 根据有限元方法的基本原理，用NCAP-2D有限元程序对尹中高速公路施工过程进行了模拟，分析了应力、应变及位移特征；同时建立了有断桩及桩间距改变时的有限元分析模型，综合对比研究了缺陷桩对地基加固的影响。本文以尹中高速公路路基处理为例，对高压旋喷桩复合地基进行了设计计算并对施工过程中遇到的问题进行了分析；在设计参数的合理选取上提出了自己的看法和建议。

High pressure jet grouting pile technology has been introduced into China for more than forty years since 1970s. At that time, this technology was mainly used in consolidation of soft-soil foundation,it was applied in impermeable dam after 1980s.At present, it has bee n spreaded over the country, and applied in large-scale projects such as the Xuan-Da expressway and Jing-Qin expressway. The technology has remarkable characters of safety, better suitability on soil, lower noises, high pile shaft strength, controllable consolidation figure, aboundant material, lower price and so on; so it is widely applied in consolidation of building foundation, deep foundation pit excavation and retaining, stability of slope, impermeable dam, etc. Soft loess foundation of Yin-Zhong expressway mainly distributes in the ditch spot which expressway acrosses the mountainous area, the distributed scope and basal surface is relation with the river erosion degree. Water content of soft loess in this area is high, W=24.5~35.1%,W≥WL,natural void ratio e0=0.68~1.31, the compressibility is big, the intensity is low. The degree of saturation is big, Sr=81.7%. IL=1.10,mostly assumes soft plastic to flow plastic, the engineering geology nature is bad. After the analysis and computation, the ground biggest subsidence quantity is 815.5mm, the bearing capacity of the foundation is about 70~100kPa. The soil filling depth of this soft foundation generally is 3~7.95m, the bearing capacity of the foundation should above 150~200kPa, the subsidence quantity should be smaller than 300mm, the stable safety factor should be bigger than above 1.1.Obviously this soft loess foundation cannot satisfy the request of the highway engineering, also because the depth of fill is bigger, the soil body and the ground are unstable, can produce skids. The basic principle of FEM and analysis software used in the paper are introduced, the construction procedure of Yin-zhong expressway is simulated，the stress, the strain and displacement characteristic are analyzed . Simultaneously established the model which had broken pile and the pile spacing changed .according the contrast results studied the influence of the flaw pile to the ground reinforcement .Taking Yin-Zhong expressway subgrade treatment for an example, This paper designs and construct High pressure sprinkling grouting composite foundation. Analysis the question which met in the construction process .Through the research of the article, the author advances personal opinions and suggestion on reasonably selecting parameters of devise, which has been proved by engineering data.