旋喷桩在既有铁路软弱土地区框构桥涵顶进工程中的应用

在既有铁路施工下穿桥涵，需将该区域的路基材料和部分地基土挖去，显著改变了铁路原有的路基、地基状态，并改变地基所承受的长期荷载；同时其便梁、基坑等临时结构也改变了周围岩土体的受力状态。这就给软弱土地区的中型、大型框构桥涵顶进施工带来了一系列的难题。利用旋喷桩施工机具小型、轻型的特点，对于顶进桥涵本身的地基加固、便梁基础稳定性以及对路基预处理进行加固防护等问题得到了很好的解决方法。

Application of Chemical Churning Pile in Jacking Engineering of Frame Bridge Culvert for Existing Railway in Soft Soil Region

The culvert construction under existing railway requires excavation of subgrade material and part of foundation soil in this region so as to change the current status of original subgrade and foundation greatly and also the long-term load born by the foundation; while the temporary structures, such as auxiliary girder and foundation pit, change the stress state of surrounding rock and soil mass as well. Both bring a series of difficulties to jacking construction of medium and large frame bridge culvert in soft soil region. With small and light chemical churning pile construction machines and tools, many problems, including the foundation reinforcement of jacking culvert, stability of auxiliary girder base, pre-treatment of subgrade for reinforcement and protection, are solved well.