Vertical Bearing Capacity Test And Finite Element Analysis On Large-Diameter Deep-Length Bored Cast-in-Situ Pile

Pile foundation has a long history, and which is a widely used form of structurefoundation. When the foundation soil is thicker weak grass-roots level, in most casesusing pile； when is deep-water soft base, pile is almost the only viable form of thefoundation. With the expansion of the scale of modern engineering construction,engineering superstructure size is increasing, a higher demand on the pile bearingcapacity, the pile development toward to large-diameter, deep-length direction and soon.Pile bearing capacity has many factors, the pile-soil interaction is very complex, sothe pile has been a hot and difficult subject in the field of engineering research. In recentyears, large-diameter deep-length bored cast-in-situ piles in engineering own universalapplication, but is not enough in-depth research on large-diameter deep-length boredcast-in-situ piles at home or abroad. Understanding of the load transfer mechanismabout large-diameter deep-length bored cast-in-situ pile is not clear, can not make aeffective analysis about the pile bearing behavio, and the current pile designspecifications remains the calculation of the ordinary pile theory, is not based on thecarrying mechanism, can not effectively guide the design of large-diameter deep-lengthbored cast-in-situ piles, all of this seriously hindered the development of large-diameterdeep-length bored cast-in-situ piles.The paper is based on pile theoretical and experimental methods summarized,according to the characteristics of large-diameter deep-length bored cast-in-situ piles,with the large-scale finite element software, combined with the static load test andOsterberg method test in project situ, the vertical bearing performance of large-diameterdeep-length bored cast-in-situ pile were analyzed. The main work and conclusions ofthe paper is as follows:(1) Based on considering the pile-soil interaction, use finite element numericalsimulation methods for investigating the pile length, pile diameter, pile elasticitymodulus, soil strength, soil cohesion, bottom sediment and other factors on the pilevertical bearing capacity, and comparative analysis of the distribution law of the pileside resistance and end resistance.(2) Make a static load test on8#pile of Ha Erbin-Dalian high-speed rail project,combined with the finite element numerical simulation comparative analysis of single pile bearing characteristics, and verify the feasibility of numerical simulation of pile-soilinteraction analysis, as a pile bearing capacity reseach effective means of analysis,andanalyse the pile vertical bearing performance.(3) Make a test on pier C4#pile of Xiamen-Zhangzhou cross-sea bridge project byOsterberg method. This method breaks the short comings of the traditional static loadtest, and obtain a better result, and test results and numerical simulation were comparedto identify the difference between Osterberg method and the test loading on top of thepile, the pile side resistance measured by Osterberg method is smaller, and analyze thereasons for the soil easily destruction at the single pile adjustable, and provide areference for future design.