Load Test And Analysis Of Bearing Capacity Of Large Diameter Bored Piles

Along with the construction development in speedways, express railways, long-span structures and tall buildings in china, the requirements of bearing capacity of foundations which support the upper structures have turned out higher and higher. Large-diameter bored piles have been in general used for high bearing capacity, small deformation and they are one of the most used foundations in constructions of bridges, ports and buildings in our country. Owing to large-diameter bored piles' high bearing capacity, it is difficult to make field test. So, there is few integrated test report, which restrain peoples' full understanding to the. load bearing performance of the large-diameter bored piles. Based on the in-situ static load tests of large-diameter bored piles of Lian Shui river larger bridge, the paper employs the method which combines the theoretical analysis with load tests in-situ, grey theory and FEM analysis and studies the load bearing performance of the large-diameter bored piles and comes to some conclusions as follows:(1) The in-situ static load tests of two large-diameter piles of Lian Shui river larger bridge and the design of reaction system was completed. Based on the tests ultimate bearing capacity of tested piles and side friction of the different soil layers was obtained. Meantime regularities of the development of pile side friction and load transfer law was researched.(2) The extended compatibility deformation was used to analysis the pile-soil interaction. Verifying by the test data, the results coincide better to a certain extent, it can satisfy the engineering requirement.(3) In order to fit the load-settlement curve of large diameter pile, the improvement of discrete GM(1,1) model is used, and the method is proved to be reliable in the engineering application.(4) Based on the parameters of in-situ tests the FEM model was established by the ANSYS FEM analysis. The regularities of pile top settlement, axis force in pile, frictional load of pile, the displacement around the pile and plastic deformation are studied by the related software. Also the factors affecting the vertical bearing behavior of pile are analyzed such as pile length, pile diameter, deformation modulus of soil, adhesion force of soil, internal friction angle of soil.