Research On The Earth Pressure Arithmetic And Load Bearing Character Of Covered Sheet Pile Wharf Structure

Sheet pile wharf is a wharf with small and medium size which is commonly used at home and abroad. In the allow-driven into the soil or in-place post sites, sheet pile structure is the most economical form. This wharf includes of a sheet pile wall which shelters from soil, pull-poles and an anchorage wall. Related to the height of sheet pile wall, the thickness of it is very small, it is a flexible structure. The upper portion of the sheet pile wall is pulled by the anchorage system, the lower part needs to embed in a certain depth below the dug face in order to maintain the stability of the sheet pile wall.The common height of the sheet pile wall would not be appropriate for more than 20m, it is mainly applied to small and medium sized wharf. If it is used for deep water ports, in order to fulfill the requirements of the stability and deformation of the wharf, it needs to design a very thick sheet pile wall to support tremendous lateral earth pressure. It's not only increasing the difficulty of construction, but also taking more costs.In order to meet the needs of great deep water ports, after years of sheet pile wharf structure designning practice, the CCCC FIRST HABOUR CONSULTANTS CO.,LTD designed the covered sheet pile wharf, and had successfully built 10 million ton deepwater wharf. Compared with general sheet pile wharf, the covered sheet pile wharf adds a row or rows reinforced concrete piles(those are, sheltering piles) between the front wall and the anchorage wall, that are closed to the front wall, but still remain 3-5m spacing from it. Sheltering piles, the front wall and anchorage wall three are tied by steel rod on the top. Sheltering piles have rectangular cross-section. The function of sheltering piles is to support some earth pressure, to reduce the pressure on the front wall, finally, to reduce the thickness of the front wall.As a structure of new development, there is still no mature calculation method of covered sheet pile wharf. The CCCC FIRST HABOUR CONSULTANTS CO.,LTD adopt FEM and simplified model computation method to analyse this structure, finally, their computing results existed some bias with the test results by Nanjing Water Conservancy Research Institute. Therefore, as a new form, the earth pressure and the analytical method of covered sheet pile wharf's stability are the desiderating problems to be solved.The main tasks of this article are:1. According to the load bearing character of covered sheet pile wharf structure, through the study of horizontal unloading arches'form and present conditions between sheltering piles, divide this structure into five earth pressure calculation parts, then, calculate the earth pressure of various regions on this structure with Rankine, Kullen and the principle of parallel walls, give theoretical calculation results in the clayed soil and unclayed soil cases, which can simplify the calculation of the earth pressure on this structure.2. Establish the finite element analysis models of covered sheet pile wharf, compare finite element calculation results with prototype measurement test results through the earth pressure of the front wall and sheltering piles, prove the correctness of the finite element model, and then in the clayed soil and unclayed soil cases, by comparing the finite element method with the theory computation results, to validate the designning earth pressure theory of the structure.3. Based on the simplified arithmetic of the earth pressure, by comparing the earth pressure of traditional sheet pile wharf's front wall with that of covered sheet pile wharf's front wall, to analyse the sheltering effect of sheltering piles. Then, by establishing a finite element model of traditional sheet pile wharf structure, compare the earth pressure, bending moments and drawbars'force of it with those of covered sheet pile wharf structure, describe the sheltering effect of sheltering piles in finite element point.4. Through the two major factors that the distance between the front wall and sheltering piles together with the space of two sheltering piles, to optimize this structure. Analyse the effect of the relevant parameters, give the reasonable results.5. Refer to the information of actual project, using the finite element models and the designning earth pressure theory above, to calculate the earth pressure and the bending moment of the front wall and sheltering piles in the project, and by changing the distance between the front wall and sheltering piles together with the space of two sheltering piles, draw the earth pressure diagram of the front wall, to validate the optimization conclusions.