Experiment Study On Mixed-In-Place Pile Improve Slope Soft-Soil Foundation's Engineering Properties

Mixed-in-Place pile was first developed successfully in the United States at the beginning of 1940s, after decades of research and development, which has been widely used in Civil engineering, such as the Harbor construction, in many countries. At present, it has been intensively studied about the mechanical properties and influencing factors of the cement -soil mixing pile, but the theory of the mechanism on composite foundation of the cement -soil mixing pile has not mature, which needs to further study. The research on slope soft-soil foundation is in initial stage, and the understanding on the failure mechanism of slope soft-soil foundation is inadequate.In order to fully master the deformation characteristics of slope soft-soil foundation under loads of embankment and find to reasonable strengthening measures of the foundation, there's a field test at a research site in new-building capacity expansion and conversion project between DAZHOU and CHENGDU. This essay uses the above project as a prototype, and designs 6 groups indoor geotechnical centrifuge model tests based on the foundation processing program of the Mixed-in-Place pile. Through the collation and analysis of the experimental data, the main conclusions are as follows:1)By adopting different pile spacing layout style at the upside and downside direction of the slope, it can reduce the differ deformation of the slope soft-soil foundation along the lateral side and improve the uniformity of the foundation treatment;2) It has better deformation binding effect by setting up the tilted pile in the downhill side of the slope soft-soil foundation, but it has less effective performance in controlling the vertical subsidence;3) The slope soft-soil foundation deformation that appeared at the downhill side will give rise to the same direction deformation at the uphill side, and the horizontal deformation is more obvious. The foundation treatment should put emphasis on the deformation controlling of downhill side;4)The varying law about horizontal deformation along the depth direction shows para-curve style which is first adding then reducing and hyperbola style that is humdrum reducing, attribute to the density of the pile layout.5) The non-uniformity of the slope soft-soil foundation in the structure has significantly effects on the mechanical response of the foundation, such as the pressure distribution and load-sharing;6) The use of the varying pile spacing mode can adjust the distribution of pile-soil pressure, and better adapt to the change of the thickness of the soft-soil foundation and improve the uniformity of foundation strengthening;7)The pulling force of the reinforced cushion geobelt is combined effected by many factors, such as the embankment loading, the thickness of soft-soil foundation and pile spacing arrangement. The distribution patterns has significant feature of the asymmetry. There is good consistency between the appearing position of the maximum value and the possible deformation location of the slope soft-soil foundation.