The Calculation Of Earth Pressure And Research On Stability Of Embedded Cylinder Structure

Port and coastal engineering construction is developing quickly with the prosperity of world seaborne trade, resulting in fine geological conditions of coastline becoming less. This makes ports and coastal engineering begin to develop poor foundation conditions of deep soft soil and silt foundation etc. It is often difficult to meet the requirement of the project construction, because of the expensive construction cost or the difficult process of construction if using traditional gravity type structure or high pile structure. Embedded cylindrical structure is a new type of structures applied in east breakwater of Xu Wei port in 2013. This kind of structures is suitable for the poor foundation conditions, such as silty seabed and deep soft soil foundation. At the same time, the structure can be prefabricated on land and be installed offshore. So it has the advantage of low cost and short duration. The structure has a broad application prospects in the seabed and deep soft soil foundation because the port is developing towards big scale and deep water. However, the embedded cylinder structure is different from the structure of gravity and high pile structure. The structure has a complex interaction with foundation soil which results in a lack of relatively mature calculation theory or method in the distribution of earth pressure, the structure’s stability, etc. So it is urgent to carry out the relevant theoretical research to improve the design of embedded cylindrical structure theory system on soft soil foundation. Therefore, the paper makes an exhaustive study on stress calculation, stability and interaction mechanism between structure and soil The main contents are as follows:The paper establishes the computation model of structure on the soft soil foundation according to the working mechanism of the embedded cylinder structure in the silty seabed. Then the calculation methods of the earth pressure, the frictional resistance, and subgrade reaction suitable to the model are proposed. Finally, the horizontal limit load is solved from the static equilibrium equation.The paper established a finite element model of embedded cylindrical structure on the soft soil foundation under horizontal load in ANSYS which is a large-scale general finite element analysis software. The soil is simulated by Drucker-Prager Model and the interaction with the structure is analyzed by contact. The paper simulates wave force on the structure by applying horizontal concentrated load of different values. By this method, the paper analyses the structure’s displacement under wave force of different values.The horizontal load-structural displacement curve is drawn according to the results of numerical calculation. The horizontal limit load is got by the horizontal load-structural displacement curve and maximum displacement values while the structure working fine. The value of the horizontal limit load is compared with the results got from the equation of static equilibrium above.The paper researches the regularities of distribution of the soil outside the structure in the vertical direction and along the horizontal direction. The pater also researches the regularities of distribution of the soil within the structure and the function maintaining stability of the structure.The paper researches different results of set bulkheads or not in the structure. Then the paper analyses the effect of bulkheads in maintaining stability. The paper also analyses the effect of the backing deal in maintaining stability by simulating the backing deal couch soil or not.The paper researches the effect of soil parameters in maintaining stability by setting different values of cohesive strength, internal friction angle and density of soil.The paper set the different coefficient of friction between the structure and supporting course to research the influence of friction on the stability of structure. The paper set the different depth of penetration to research the influence on the stability of structure.The research results show that the destruction forms of embedded cylinder structure is overturning failure under the horizontal wave force.In overturning limit state, the earth pressure of lower cylinder outside is not reach the limit. The value of earth pressure increases along the depth nonlinearly and the value of earth pressure in cylinder equals that of earth pressure at rest approximately. The bulkhead, soil parameters, backing deals, supporting course and the depth of penetration can influence the stability of the structure except the friction between the structure and supporting course.