The Research On Bearing Capacity Of Concave Ribbed Uplift Pile

In this paper,a new type of concave ribbed pile is studied.It is made by using special mold,pretensioned method and centrifugal forming process in professional factory.It combines the advantages of prestressed hollow square pile and ribbed square pile.Because of concave rib,the traditional static pressure penetration method can be used,it has other advantages such as simple construction method,short construction period and clean construction as well.On account of different resisting increasing mechanism,the bearing capacity of concave ribbed pile needs to be deeply studied.In view of the new pile type,the load-bearing performance is studied by numerical simulation and full-scale structure test.The main work is as follows:(1)Through FLAC3D finite difference numerical simulation software,the vertical uplift bearing capacity of the concave ribbed uplift square pile,the bamboo section pile and the common square pile under the same pile-soil material parameters are compared.By changing the parameters of the concave ribs,the change of the pull-out bearing capacity under different sizes and spacing of the ribs is explored.(2)The formulas of cracking moment and bending capacity of the failure control surface of the new pile type are deduced.The bending capacity of the pile type without connecting,the welded connecting pile type and steel hoop type are studied through four point pure bending experiment,the cracking moment and ultimate moment capacity are determined.Compared with the standard value;the difference of the bending capacity,failure characteristics and crack distribution between them are compared.(3)Through low-reversed cyclic loading experiment among the pile type without connecting,the pile type with welded connecting and steel hoop connecting,there seismic behavior are studied.By observing the failure characteristics,comparing the hysteretic curve,skeleton curve,stiffness and strength degradation,and energy consumption performance,the differences in seismic performance between the pile type without connecting and the pile type with welded connecting are studied.At the same time,the improvement programs are presents.