Deformation Analysis Of Soft Soil Sub-grade On Maanshan-Wuhu Expressway

With the quick development of expressway in the soft soil area, the settlement and deformation of sub-grade of expressway has become a very outstanding question. This paper establishes the corresponding formulas of sub-grade 3-D (three-dimension) settlement on inartificial foundation, bagged sand-drains foundation and semi-rigidity piles foundation, and the calculation results from the formulas is compared with the observation results of settlement. It proves that the methods adopted by the paper are feasible.Because there are many factors affecting the properties of soft soil, the paper considers several following main factors: stress history, change of additional stress, lateral deformation and loading style and speed. The 3-D settlement theory is established. Loading by stages is considered in the bagged sand-drains consolidation theory. The equivalent layer of composite modulus method is used to calculate settlement of composite foundation of DIM (Dry Jet Mixing) piles. The author compiles the corresponding program about the above-mentioned formulas in Turbo C of computer language. The comparison of calculation results and observation data shows the following conclusion: The settlement of sand-drained foundation is obviously larger that of DJM piles foundation, and DJM piles can obviously reduce the settlement of sub-grade, and the calculation value comparatively accords with the observation value on the whole. Accordingly, the author thinks the settlement theory of the paper can be used for the settlement calculation and estimation of later practical sub-grade project.