Studies On The Micro Steel Tube Piles Gravity Cement-soil Retaining Wall Mechanical Properties And Its Influencing Factors

The gravity cement-soil retaining wall have been widely used in the deep soft soil foundation pit supporting engineering, because of the soil retaining, fast construction progress and strong economy advantages. The foundation pit support structure of micro steel tube pile gravity cement-soil retaining wall is consisted by inserting the micro steel tube piles to gravity cement-soil retaining wall. In recent years, it has been successfully used and promoted in soft soil area in Guangzhou. Effectively controlling the horizontal displacement of retaining wall, reducing the surface settlement and soil uplift at the bottom of foundation pit can be realize by inserting micro steel tube piles, that make it successfully improves the integral stability of foundation pit supporting engineering. What’s more, it reduces the width and embedded depth of the retaining wall effectively, which has good economy and a wide range of engineering applicability. So far, just a handful of people have an in-depth study on the supporting system of micro steel tube pile gravity cement-soil retaining wall, the understanding and studies of the the mechanical characteristics and its influencing factors of supporting structure is still in a state of blank. Therefore, an in-depth and systemic study of this type of supporting structure is of great value.Firstly, this paper starts with summarizing to the background, the research theory and the engineering practice of the micro steel tube pile gravity cement-soil retaining wall; Based on the distribution of hydrologic geology and the mechanical parameters of soft soil in Guangzhou, to discuss the design theory of foundation pit, construction practice and earth pressure computation model in soft soil area. Secondly, according to the construction equipment selection, plane and section arrangement types of the micro steel tube pile gravity cement-soil retaining wall layout principle, to discuss the applicable scope and economy. Combined with the deformation and failure mechanism of gravity cement-soil gravity retaining wall, the mechanics index selection principle, horizontal displacement of supporting structure, the width and the embedded depth of retaining wall, the surface settlement and the soil uplift at the bottom of foundation pit will be given. Finally, this paper constructs a three-dimensional model to analysis this type of supporting structure by using the finite element software. Mainly study the various influences that the micro steel tube pile gravity cement-soil retaining wall made to both the internal force of support structure and the deformation of foundation pit under different conditions, probe the inner influencing rules in the deformation of Pit and the internal force of support structure related to the factors including the effects and laws of the length, external diameter, external diameter of the inserted micro steel tube piles, the embedded depth of cement-soil retaining wall, reinforcement inside the pit and the elastic modulus of cement-soil retaining wall etc. The change laws of the maximal horizontal displacement of cement-soil retaining wall, the maximal surface settlement, the soil uplift at the bottom of foundation pit, the maximal internal force of micro steel tube piles, the cement-soil retaining wall stress according to different factors are given. Meanwhile, comparatively analyzed the results of finite element calculations and field monitoring data with the three-dimensional finite element model set up by considered engineering examples. It turns out that the rationality of the3D model was verified and its value of being referred for similar projects was confirmed.