| ABSTRACT:The super-long bored pile has become all indispensable style of foundation at the highway bridges, especially at the spanning great rivers and gulfs bridges. But researches of the engineering properties of super-long piles are not sufficient for the requests of application, and we have not a befitting theory to guide the designs and calculations of the super-long bored piles, at the same time the economy and security of the super-long bored piles are not ensured completely by the methods and parameters of the existing code. For the problems upwards, we have done much of pertinence work. By collecting data and doing experiment, we have comprehensively known the application and research status quo of super-long bored piles and we have done a great deal of researches including analysis of load transfer mechanism and bearing capacity calculation, the effective pile length and so on, the main work are as followings:1. The model and solution of the transfer function of super-long pile under axial load was systematically introduced, super-long pile’s load transfer characteristics was analyzed, the pile foundation’s load-displacement curve of various circumstances was statisticaled, and the principle and method of pile foundation bearing capacity which determined by the load-displacement curve was expounded.2. I applied Ansys software to establish finite element computation model of piles and soil, to analysis the interaction of the soil and the pile and research the influence that the variety of the design parameters exert on the bearing performance of super long bored piles.3. According to the principle of the balance test and the analysis of load-displacement curve, the test pile’s ultimate bearing capacity are obtained.4.The method of settlement control is used to determine the effective pile length of super-long pile, which can provide a reference method to the optimize design of super-long pile.5. According to the second chapter’s theoretical achievements of the total stiffness of piles and soil, and based on curve relation analysis between the total stiffness and pile length of piles and soil, the feasibility of this method to determine the effective pile length is studied. |
