Analysis On The Vertical Bearing Capacity Of Large-Diameter Pile Under Water

With the rapid development of large scale of port and bridge projects, more and more large diameter piles under water which bearing vertical load are used in the captioned project, and the research of bearing properties about large diameter pile under water are regarded more and more. The paper analyzes the law of deformation of large diameter steel piles under water which bearing vertical loads on the basis of the analysis of bearing capacity in field test.The paper looks back the research results of bearing vertical load of single pile at domestic and overseas, and summarizes the analysis and test methods of large diameter boundary piles underwater of bearing capacity, and on the basis the analysis of test results of bearing capacity of large diameter steel pipe piles under water of four piles of two projects, and discuss the properties of bearing vertical load of large diameter steel piles under water. According to the test results in situ, analyze the law of press and deformation which changes with the development of vertical load of large diameter steel piles under water. The internal load and shaft resistance of pipe piles can be computed from measured results of pipe strain, and then the distribution model of shaft resistance, load transfer and deformation characteristics of larger-diameter steel pipe piles were analyzed. The results show that the load-settlement relation of large diameter pile underwater is slow variant, no show obvious drastic changes damage properties. The distribution patterns of axis force is close to the ladder type. Upper soil surface for the linear is straight, the mud below the surface for the linear is decline, and has a terminal resistance. The friction of pile side in shallow soil can be fully played, and during the whole trial process, the performance was satisfactory elastoplastic; The friction of the bottom layer in the ultimate strength never giving full play, is continuing to grow, and the basic characteristics is a flexible line; Pile bottom has low-resistance early, rapid growth of late.For further to analyze the interaction of pile and soil under vertical load, The capacity of large diameter pile underwater has been tested which uses high strain dynamical test, and compare to the test results of static load. The results indicate that the test results of discrete are smaller, and relatively more stable and reliable based on the analysis of pile high strain of fighting in early testing and repeat testing. Compare dynamic results with static results, the error is relatively small, which can guide the piles of construction works based on dynamic test results.The ultimate strength of the pile was increased in the same token with the interim period of growth, the coefficient of steel pipe pile was still increased with the interim period of growth.Through the analysis of load transfer and application of the large-diameter pile underwater, and the design, construction and testing of large-diameter underwater pile are proposed. In this paper, the conclusions can be as reference for the design and construction.