Analysis Of The Bearing Capacity Of The Existing Bridges Pile-Group Foundation Under The Surcharge Load

With the sustainable development of railway, highway construction scale in our country and total mileage of railway, road Bridges is growing, but due to the limitation of various factors such as construction conditions and environment, natural filling soil and the construction of the discard filling large accumulation around the bridge pile foundation often appear.There are two aspects of the results in filling pile load mainly.On the one hand, bridge pile foundation led to bending deformation, which was caused by horizontal displacement of pile to soil, resulting in the upper structure deviation that can’t even normally work; on the other hand, the Pile makes the further consolidation of soil and causes the soil and pile body relative displacement so that produce larger negative friction resistance, and thus the bearing capacity of pile foundation and produce uneven settlement. As you can see, the adverse impact of the effect on bridge pile foundation, pile load bearing capacity and deformation pose a serious threat on railway transportation and people’s life and property safety. So the existing bridge pile group foundation under the influence of pile load bearing characteristics and deformation law, evaluate whether it is necessary to meet the requirements of the design bearing capacity and deformation.The summary based on the analysis of the impact in recent years at home and abroad, is deduced by the elastic theory under different pile load level, pile load distance theoretical calculation formula of bearing capacity of pile foundation; Corresponding with the theoretical calculation, the establishment of three-dimensional finite element model, it is concluded that the single pile and the pile group with heap load level and the distance change of pile foundation bearing capacity and deformation law of development; On this basis, the analysis of the pile foundation of pile and soil in the three dimensional finite element consolidation, for pile foundation settlement and internal force along with the time development regularity, and compares them with the field measured data analysis to prove the validity of the analysis, the main research results of the paper are as follows:1)The research of bridge pile foundation under the influence of the pile load bearing characteristics and deformation theory calculation and analysis method, and introduces the characteristics and complexity of pile foundation under the influence of pile load bearing, which laid a solid foundation for the research of this paper.(2) On the basis of existing research and specification calculation, based on the theory of elastic semi-infinite space effect on the surface of a vertical concentrated force F, half space was a bit of stress and displacement of elastic mechanics, aiming at the complexity of the problem solving, with the aid of Matlab programming constructs the corresponding calculation program, is derived as a point of stress and displacement of pile soil, thus deduces arbitrary heap load level, the stack from the order and the analytical solution of bearing capacity of pile foundation;And according to the theoretical calculation model of three dimensional numerical model is set up, the bearing capacity of single pile and pile group foundation is studied and the pile group effect coefficient along with the development of the heap load level and the distance change rule, and compared with theoretical calculation of formation analysis;Finally put forward different stack distance calculation formula of the corresponding security stack level.(3) Establish the pier foundation settlement observation system automation, analysis of the bridge pier foundation settlement deformation law of development, to assess their service status; Line with dahlia RuanTu District large area deep stack in bridge pile foundation diseases typical worksite as the background, establish quincuncial piles used in practical engineering of pile foundation in the heap of three-dimensional finite element model of consolidation under the whole group of the settlement of pile foundation under the influence of pile load and stress characteristics over time and analyze the law of development, provide guidance for practical projects.