The Application Study On Pile Foundation Beam Retaining Wall Of Substation High Fill Slope

Pile foundation beam retaining wall is a new type of slope retaining structure, At present, there are not many theoretical researches about it. This paper takes Guangxi Power Grid Corp project "the applied research about high slope retaining structure of substation" as the basis, using the method of the method of combining theoretical analysis and numerical simulation, to research the applicable condition and reasonable size of pile foundation beam retaining wall in high fill slope retaining structure design of substation. This provides the reference for the popularization and application of pile foundation beam retaining wall. The main works of this paper include:Through the theoretical research, this paper summarizes the conventional design method of the retaining wall, beam and pile foundation without considering the interaction of retaining wall, beam and pile foundation. The study emphasizes the effect which the size and support conditions of the cross section of the beam on its internal force and deformation. At the same time, the beam is simplified respectively as a continuous beam and Winkler elastic foundation beam to analyze. The result shows that:when the flexibility characteristic value λ≤0.2, the beam can be designed according to the continuous beam, or should consider the role which foundation soil has on the beam. For the optimization of beam structure, this paper suggests that across number should choose3above and Span from5m to8m is relatively appropriate. At the same time, cantilever sections can be set up at both ends of the beam and the cantilever length is appropriate for1/4～1/3of the span.Two-dimensional finite element model is adopted to simulate the pile foundation beam retaining wall and study the internal force and deformation of the structure considering interaction of the retaining wall, beam, pile body and foundation. The influence which the changes of various parameters have on the stress deformation of retaining wall and the internal force of pile body is analyzed. The research results show that the control effect which pile has on retaining wall displacement is remarkable. There is little effect the elastic modulus has on the earth pressure behind the wall. The earth pressure intensity of the top wall increases with the increasing of the cohesion. The earth pressure intensity decreases with the increasing of internal friction angle. There is little effect elastic modulus has on the force of pile body. The changes of the pile length impact distribution rule of the internal force in the pile body.By using finite element strength reduction method, the effect that the height of retaining wall on the slope slip surface and stability coefficient is analyzed. The results show that:the stability coefficient increases gradually with height of the wall increasing. For the fill slope that the height is21m, when the height of the wall less than9m, the sliding surface will slide out from the top of the wall, and the retaining wall height should not be less than10m.Combined substation high fill slope engineering instance, at the natural state, the stability coefficient of slope does not meet the requirements; the balance weight retaining wall can’t meet the requirements of the foundation bearing capacity and stability value-for-weight retaining wall foundation bearing capacity and stability. Using pile foundation beam retaining wall, slope stability can meet the requirements. This paper presents the size of the optimized pile foundation beam retaining wall, and compares the theoretical solutions with the numerical solutions. It can be concluded that the safety factors of slope after reserving meet the specification requirements. The results of numerical calculation are reasonable. The optimized pile foundation beam retaining wall is economic and reasonable.