Fem Analysis Of Deformation Trait Of Gravel Pile Foundation Under Large-scale Oil Tank

In the design process of the oil tank foundation, if the deformation is estimated insufficient, the small impact will be caused by engineering structures splited, the large impact will be triggered serious accidents such as dumping and course the huge economic losses. Many examples show that all sorts of foundation treatment method can resolve successfully uneven settlement problem of the tank. Vibrofluctuation Crushed Stone (VCS) piles foundation reinforcement was applied, combined water filling preloading consolidation method, so as to give full play this feature, the gravel pile drainage effect and oil foundation before water filling preloading was used. Thus it could reduce the cost of foundation reinforcement and eliminate foundation consolidation settlement.It is a kind of rational economic reinforcement method of the tank foundation. Therefore FEM analysis of deformation trait of gravel pile foundation under large-scale oil tank are both theoretical significance and value.Based on the SKIKADA Algeria to large tanks refinery soft vibro-replacement stone column water filling preloading combined with the field test, controlled systemic the deformation of the tank was the main research targets. The large-scale finite element numerical analysis software Plaxis was applied to establish a two-dimensional finite element model for the foundation type. Axisymmetric FEM was introduced in the numerical simulation analysis and calculation. Compared with different length distribution, length, Exchange rate unchanged, the diameter or change of pile spacing, Pile diameter, pile spacing of exchange rate changes, the length of the cushion course of the tank foundation were analyzed on the differential settlement of gravel pile foundation under large-scale oil tanks; the effects of diminishing the differential settlement by Compared with each parameter; Compared with the relation of lateral displacement and differential settlement, the optimal solution of diminishing the differential settlement were evaluated.Finally, the result of Axisymmetric FEM Compared with the field data. At the same time, the effect of strengthening was evaluated; Through the long-term monitoring of deformation of the deep soil and surface soil, a great number of primitive data were obtained. In this paper, the plane inclination and non-plane inclination of the surface and deep soil, and the sway settlement of the round wall are discussed. The settlement of the oil tank foundation is analyzed and evaluated. Main concluded:(1) in the general engineering design, the gravel pile foundation could be simplified by the circle to simulate tank for 2-d numerical computation.(2)Difference settlement of foundation changes with different pile length distribution scope, which, with long pile:0m-0.33D,0.33D-0.39D or 0.33D-0.42D (D-tank diameter) is a minimum;in the center scope of composite foundation, through fixed pile diameter, reduced pile spacing to increase replacement rate, could make the composite foundation in relatively smaller conditions for displacement rate obtained differential settlement;in the center scope of composite foundation, kept exchange rate, pile diameter is more bigger(and the pile spacing, gravel pile foundation is looser) the difference settlement is more smller, With the increasing pile diameter increased, differential settlement of changing is lesser; When mattress level arrangement rate for oil pot floor space 60%, the unequal settlement achieves is smallest;different adjustment methods of differential settlement by adjusting the length discoved, through adjusted the long pile distribution, the rate of displacement could reduce different settlement, but changes the mattress level the effect is not very obvious;the foundation of lateral displacement of negative differential subsidence appears to be one of the most important features of adjustment.(3) Under the different breaker strip module, gravel pile thrust pad gravel layer, And, with the increase of cushion modulus, the amount of gravel pile is smaller, Below distance head of pile in certain distance, there is no settlement difference problem. The breaker strip module's change punctures the quantity to the head of pile on the influence to be big, the breaker strip module is bigger, on the head of pile punctures the quantity to be smaller;as foundation stiffness becomes smaller and smaller load or replacement rate or the scope of the lateral inflation will become gradually larger, But, no matter how the various factors, the corresponding changes in the maximum lateral inflation is below ground constant depth (in this case depth for 2.5 m),(4) The water gravel pile construction played a role of vibration, eliminated sand soil liquefaction, elimination of foundation soil, improve the intensity, The vibro-replacement stone column and water filling preloading treatment after reinforcement, the bearing capacity of compound foundation 225kPa eigenvalue, allow to design requirements. The plane inclination and non-plane inclination of the surface met the standard value of deformation of foundation, the soft soil can be improved reasonably by the VCS piles combined with preloading, finite element numerical simulation could be applied to help explain the actually-measured data...