高速铁路深厚土层地基处理技术与沉降计算

Treatment Technology of Deep Soil Foundation for High-speed Railway and Settlement Calculation

高速铁路对工后沉降要求严格，无碴轨道对桥路、隧路过渡段差异沉降限为5mm，一般路基地段工后沉降限为15mm。因此，我国不少在建客运专线需要采取措施对地基进行处理，以有效控制地基沉降。在深厚土层地基上修筑无碴轨道，现行地基处理措施主要为CFG桩、预应力混凝土管桩及路基桩板结构。文中分析了各种复合地基承载力及沉降的计算方法。提出当应用CFG桩和预应力管桩处理深厚土层地基时，结合采用筏板结构，更能发挥CFG桩和预应力管桩的承载力和有效控制沉降；深厚土层地基处理后计算沉降应进行修正，其修正系数：CFG桩地基处理复合模量法为0．2左右，管桩地基处理桩基法为0．2～0．4。

High-speed railway has higher requirement on post-construction settlement. Differential settlement in transitional section of bridge connection or tunnel connection with ballastless track on subgrade is limited to 5mm, while post-construction settlement is limited to 15mm on normal subgrade. Therefore, measures shall be taken to the subgrade of many passenger dedicated lines being built in China in order to effectively control subgrade settlement. The foundation treatment measures of the deep soil foundation for ballastless track are mainly of CFG pile, pre-stressed concrete pipe pile and pile-slab structure. This paper analyzes the calculation method of composite foundation bearing capacity and settlement calculation method, and puts forward that when CFG pile and pre-stressed concrete pipe pile are used to treat deep soil foundation, raft structure can contribute to realize the full bearing capacity of CFG piles and pre-stressed concrete pipe pile and effectively control settlement. Settlement calculated on deep soil foundation after treatment shall be corrected. Its correction coefficient is about 0.2 for settlement calculated with CFG pile composite modulus and 0. 2 to 0. 4 for the settlement calculated with pre-stressed concrete pipe pile method.