Study On Mechanical Properties Of The Thick Pile Cap

Pile cap in pile foundation structure ensures that the upper load is effectively transferredto the ground, and also limits the displacement of pile foundation; it is an importantcomponent of bridge structure. Pile cap in bridge engineering is usually under thethree-dimensional stress state, it is disturbed by many factors, the internal force of pile cap iscomplex, a lot of research on pile cap has been carried out at home and abroad, and theresearch is mainly divided into two kinds of methods, the first one is controlling sectionmethod based on the bending theory, another one is the spatial strut-and-tie model method.But the study on thick pile caps used in railway is not enough. Therefore, it is necessary andsignificant to study the mechanical characteristics of thick pile caps, especially thick pile capsused in railway. The research contents of this paper are as follows:(1) Analyze the research situation, research achievements and some deficiencies of thepile cap in pile foundation at home and abroad, compare and summarize the research results.Give an introduction to the related problems of finite element modeling, such as the nonlinearanalysis of reinforced concrete and selection of the unit during calculation, conduct relevantstudy on the common calculation methods of pile-soil interaction.(2) Make a detailed introduction to the relevant knowledge of strut-and-tie model, theapplication scope of strut-tie mode is proposed, problems about various kinds of membersand joints and angles in strut-and-tie mode are stated, and the bearing capacity of strut-and-tiemodel is discussed and studied, combined with the regulation on the strength of each memberin the design of strut-and-tie method in different countries, the establishing method of strut-tie mode and calculation method of the bearing capacity of tension and compression strut aresummarized.(3) Through the field test and software analysis and calculation of thick pile caps usedin railway, distribution of the force bearing, deformation and stress flow obtained from thecalculation are compared with the testing date, the stress distribution of pile cap is analyzed toverify that the mechanical properties of thick pile caps used in railway are in accord with thestrut-tie model.(4) Finite element analysis is carried out on the main influencing factors of the bearingcapacity, including concrete strength, thickness of pile cap, pile spacing, reinforcement ratioand the form of reinforcement, the influence regularity of various factors on the bearing capacity of pile cap is summarized, which provides the basis for the reasonable design ofthick pile cap.