Pseudo-static Experimental Study On High-capped-pile Foundation Pier Under The Action Of Horizontal Load

The high-capped-pile foundation has been widely used in china's bridges engineering of the permafrost region and bridge engineering across the sea.The bottom surface of high-capped-pile foundation is generally above the ground and the water surface,it has a free pile length and the force of pile is unfavorable,the pile internal force and displacement is larger than common pile cap under the same level force.In view of structural and stress characteristics of high-capped-pile foundation pier,research on the stress behavior of high-capped-pile foundation under horizontal cyclic loading and propose static nonlinear calculation model of high-capped-pile foundation by using the combination of static model experimental study and numerical simulation.The main research work is as follows:(1)After reading a lot of literatures,the current research status of the seismic damage to bridges,pile-soil interaction and pile foundation system in the pseudo-static model test and theoretical analysis are systematically summarized.(2)Taking a high-capped-pile foundation pier of simply supported beam bridge as the research object,pile foundation piers model based with the ratio of 1:8 are set up.the failure patterns,skelon curve,hysteretic laws,energy dissipation capacity,stiffness chara-cteristic and displacement ductility under low-cycle reversed loading are studied by using quasi-static test on the pile foundation model.(3)On the basis of quasi-static model test study,the power series analysis method and finite element method of the high-capped-pile foundation pier based on the linear M-method is discussed.The rationality of the M-method is proved by model pile experiments.(4)A nonlinear static calculation model of the high-capped-pile foundation pier under horizontal load is proposed.The nonlinear resistance of foundation soil is simulated by the p-y curve which consider horizontal resistance at lateral of pile shaft,the t-z curve which consider vertical frictional resistance around piles shaft,the q-z curve which consider vertical bearing resistance at pile tip based on the code of American API.The elasto-plastic of pile shafts under variable axial loads is simulated by PMM hinge.The rationality of analysis model is proved by model pile experiments.(5)Based on the nonlinear static calculation model of the high-capped-pile foundation pier,development process of plastic hinge and distribution law of plastic hinge under the horizontal load is discussed.