Study On The Injury Mechanism Of Bridge Piers And The Safe Capability Of Bridge Under High Filling Soil

When a bridge is constructed in the mountains or heavy hill area, valley terrain is very common, in order to save costs and to consider the principles of environmental protection, the deep under the bridge is often taken as the spoil ground by project owners and construction units. This earth fill will produce an unbalanced soil pressure in one side of the pier, which may have a greater lateral deformation, and cause offset and cracks in the piers, and the piers in serious condition will be torn dawn. In practical engineering, the spoil can often be seen around the pier, which certainly will have effect on the pier, and causes serious offset and cracks in the pier. In general case, the lateral displacement of the soil caused by the unstable state is more important than its vertical displacement, especially for concrete pier. However, the ability of the pier to bear horizontal load is not considered in the design, so it is very necessary to study the damage mechanism of the pier under the earth fill and its impact on the safety performance of the full bridge.Firstly, the research status of the pier pile in the effect of the earth fill lateral displacement are summarized and generalized, and a systematic introduction are made to the resistance effect caused by lateral displacement of the soil, and some representative theory test and calculation methods of the piles under the effect of a variety of earth pressure are also described in this paper. The theory of the finite element software ABAQUS to deal with the contact problems are also introduced, the force and displacement of the piers and the position distribution of the cracks are analyzed used the pier model under the fill based on the engineering example. In addition, the effect of the various factors on the pier is also further studied, and all kinds of factors are considered, such as the geometric condition of the pier, the soil properties, and so on.The paper aims to establish and perfect the damage mechanism of piers, as well as the damage to the safety performance of the bridge under earth fill. The main contents of the study include the following aspects:①Research how to build the three dimensional finite element model of piers under inhomogeneous and post-high earth fill.②The finite element model that affected by earth fill is built according to the engineering example and it is used to analyze the stress and deformation characteristics of the piers, study the reasons of causing cracks, analyze the damage mechanism of the piers, piles and platforms. The finite element model is also modified combining the offset of piers through actual observation.③The finite element model is used to analyze the impact factor of single pier deformation and the stress under high earth fill, such as soil density, elastic modulus, Poisson’s ratio, angle of internal friction and cohesion; elastic modulus of piers, diameter, filling height, topography slope, and so on. Study the significance of various factors on the actual project.④The full bridge finite element model is established, which combined bridge diseases, used to analyze the safety effect of piers offset under earth fill, and some simple disposal methods are suggested in the paper.