Test For Vertical Bearing Capacity Of Pile Foundation On Bridge And Numerical Simulation Analysis Of Pile-soil Interaction

As an important part of the traffic line,bridges can stride across the deep ravines,rivers and lakes and make the natural moat be thoroughfare.With the development of bridge structures to the direction of large span and heave load,the pile foundation has become the preferred form in the design of foundation for the sake of its advantages,such as large bearing capacity,small settlement,convenient construction and strong adaptability to various complex geological conditions.Under the load of superstructure,the pile foundation not only needs to provide sufficient bearing capacity,but also needs to control the settlement to meet the deformation limit requirements of superstructure.Therefore,it is highly necessary to carry out a systematic and comprehension research on this topic.In this thesis,the main works and contents could be summarized as follows:(1)The application and development history of the pile foundation,the general test methods of its bearing capacity and the present research status of pile-soil interaction are Summarized,which can provide theoretical basis for selecting the reasonable test method of vertical bearing capacity of pile foundation and applying finite element program to simulate pile-soil interaction precisely.(2)The vertical bearing performance of pile foundation,including the mechanism of load transfer,lateral resistance of single pile,tip resistance and influencal factors on the bearing capacity of single pile(the nature of soil around pile,the geometric characteristics of pile and the material of pile)are deeply analysed,which can verify the feasibility of friction pile design and provide a reference on optimizing the design of the pile foundation.(3)Based on the design and construction of pile foundation of Taiping station's four-line bridge and Jiefang village's double-line bridge,the field test of vertical bearing capacity of three testing piles is carried out with the method of static loading test and slow maintenance loading.As a result,the basic bearing capacity and the ultimate lateral resistance of each soil around the pile are obtained.The static vertical bearing capacity of single pile is determined by the load-settlement curve,which could provide basis for the design of pile foundation.(4)The finite element software ABAQUS has been applied to simulate the vertical bearing capacity of the pile foundation,and the results are compared with the field test results simultaneously.The applicability and rationality of simulating pile-soil interaction with ABAQUS has been verified.Furthermore,by analyzing the load bearing characteristics in condition of different lengths or diameters,the reasonable size of pile foundation has been determined to optimize the design,reduce the difficulty and cost of construction.