Research On Destroy Behavior And Vertically Bearing Capacity Of Bridge Bored Pile

Along with the construction development in speedways, express railways and the construction advancement of technology, long-span bridge have been developed quickly in china in the nineties of the twentieth century, so the requirements of bearing capacity of the foundations, which support the upper structures, have turned out more and more strict. The large diameter piles (LDPs) not only have stronger bearing capacity with less deformation, but also have some other advantages: flexible in application, simple in computation, convenient for construction, and economical in materials consumption, etc., thus LDPs are widely used in long-span bridge engineering. But nowadays, in the code of highway bridge only have safety coefficient for axial bearing capacity of pile foundation. Because the precision of calculate settlement of pile foundation is lower to the precision by static load test curve. So the settlement of pile is confirmed by static load test for pile-pole and the pile, which the distance of center is larger 6 times, pile diameter in the bridge code. For pile group, the settlement can been calculated by layer and summation mouth by pile group is considered body foundation, but have not given the limits value. So in the statically indeterminate structure, we cannot forecast the influences which the settlement of pile to upper structures. So how to control vertical terminal bearing capacity by settlement of bored pile is a problem which all people attention.The paper adopts Drucker-Prager model, set up a bored pile and soil contact model base on Drucker-Prager model, take a computer model analysis to destroys theory and distortion character of large-diameter bored pile under vertical load effect, analyzed through set up the computer model result and static load test result, the paper analyzed systemically the figure of side fraction and end resistance character and the relations of side friction and end resistance with settlement of large-diameter pile. On the base of analysis, through compact the load transfer models, the paper take the three-parameter model for load transfer model of pile, and compiled a Matlab programme of the model to calculate the P—S curve of pile foundation. And confirmed the bearing capacity of pile foundation by P—S curve, and compact the calculate result and computer model result with test result, proved that three-parameter model is effective for calculated the large-diameter pile.