Study On Bearing Behavior Of Large Diameter Pile

Development of super, high-rise buildings and large span buildings demands improvement of bearing capacity of foundations, which provides opportunities for application and research of large diameter pile. Large diameter pile can improve bearing capacity of single pile remarkably and can be used conveniently in design. It's very significant to study new bearing behavior of axially loaded large diameter pile to practice.Bearing behavior of large diameter pile and load transfer mechanism of single pile are analyzed and factors effected bearing behavior of single pile are discussed. The present load transfer methods of pile shaft and pile tip presented by some scholars are summarized.A great in-site static pile test is carried, which have the load-settlement curves and ultimate bearing capacity of large diameter piles. With theoretical analyzed, the result of test contrasts with that of numerical simulation in this paper.In this paper, differential equation of pile load-settlement relationship and a numerical iteration method for determining hyperbolic model of load-settlement relationship of a single pile are developed considering the pile-soil interaction. A computer program is compiled to analysis parameters in this method, by which calculations and conditions for used of these parameters are given. Comparing with results of in-site static pile test of actual engineering, the method for calculating the bearing capacity of large diameter pile is creditable.The m ethod h ow t o o btain t he e quations of three p arameters load transfer are introduced. By compiled computer program, all the parameters in this method are analyzed, and corresponding using conditions and experiential values of these parameters are given. With three parameters load transfer function, it can obtain the load-settlement curves of pile embedded in homogeneous or layered soil, which are access to the results of actual engineering. It can be see that this method is suitable for calculating the ultimate bearing capacity of large diameter pile and the empirical parameters given by this paper are justified.Stress-strain relationship of linear elastic model is used in Randolph model, in this model, the soil around the pile is assumed as elastic foundation, so it has much too distinction between the test result and the calculated result. Parameters in this model are analyzed in this paper. And a modular-modified coefficient is introduced, which modify the modular of soil in different load stage. Both the pile is friction-column pile and rocked pile, the calculated results come up to the result ofin-site static pile test of actual engineering.Comparing the theoretical methods, which include hyperbolic model methods three parameters model method and Randolph model method, with the test data, it can be see that the ultimate bearing capacity of a large diameter pile can appropriately be calculated by confirming justified parameters.