New Analytic Method for Subgrade Settlement Calculation of the New Cement Fly-ash Grave Pile-slab Structure

At present, reducing subgrade settlement of soft soil foundation is a key problem in high-speed railway construction. Pile-slab structure is a widely-utilized form of foundation structure to reduce the subgrade settlement in China. In order to save the engineering cost for high-speed railway construction in developing countries, the author developed a pile-slab structure and named it as the new Cement Fly-ash Grave (CFG) pile-slab structure. This work analyzed the settlement controlling effect of new CFG pile-slab structure and summarized two calculation methods on its subgrade settlement which are further formulated into an analytic method. Three methods were used to calculate the subgrade settlement of CFG pile-slab structure for a soft soil foundation in Chinese Shanghai-chengdu high-speed railway. The research showed that: (1) The settlement controlling effect of CFG pile-slab structure can satisfy the requirement of high-speed railway construction. (2) The new analytic method is proved to be more accurate and can reflect the mechanism of load transferring． Furthermore， the new analytic method can provide theoretical guidance for engineering designs and constructions of the CFG pile-slab structure．