Influencing Factor Analysis And Treatment Measures Of Bridge Damage Caused By Surcharge In Soft Soil Area

At present,the urbanization process of China is accelerating.And the infrastructure construction is developing rapidly.In the next few years,there will be more construction demand.However,due to the limitation of geographical location and construction conditions,engineering waste and domestic refuse are piled up around bridges,which have caused a lot of engineering accidents.Especially in soft soil area,because of the characteristics of low bearing capacity,low shear strength,high compressibility and high void ratio of soft soil,surcharge will cause large horizontal deformation,which is more likely to threaten the normal use of surrounding piles.It is necessary to study the causes of bridge damage under surcharge loading and take effective measures after the accident.Based on the investigation of practical engineering cases,this paper studies the influencing factors and treatment measures of bridge damage through theoretical analysis and FEM simulation.The main work is as follows:1.The deformation and inner force of pile under surcharge loading is summarized.The advantages and disadvantages of several methods,such as field measurement,laboratory experiment,theoretical analysis and numerical analysis are compared.2.Starting from the bearing characteristics of single pile,the soil pressure at pile side under surcharge is calculated by improved Boussinesq vertical additional stress solution.Then the soil reaction force behind pile is simulated based on the foundation compression coefficient k and foundation shear coefficient G in Vlasov two-parameter foundation model.In order to be closer to the reality,the plastic yielding of soil is considered.And the article derives the differential equation of single pile under surcharge loading.Based on a large number of literatures,the values of k,G and ultimate horizontal resistance of soil are analyzed.This chapter introduces the difference method and uses the finite difference method to solve the deflection differential equation of a single pile,then compiles the corresponding MATLAB program for numerical calculation and compares with engineering examples.Finally,several main factors which affect the horizontal loading of single pile are analyzed.3.The collapse of a bridge under large area of soil heap in Hangzhou is established by ABAQUS.On the basis of collecting data,a 3D elastic-plastic finite element model is established based on the actual situation of the project.And the finite element simulation is carried out to explore the mechanism of the bridge dumping.This paper quantitatively analyses some influence factors on the pile such as soil parameters,loading height and oblique angle,and draws a conclusion through analysis and comparison,which provides a basis for future design and construction.4.Combining with engineering examples,deviation rectification and reinforcement methods are studied based on the monitor results.The calculation is completed to analysis the cause.Jack jacking,steel pipe pile and anchor are adopted as a joint deviation rectification scheme to achieve the purpose of bridge deck deviation rectification.