Pseudo-static Experimental Study On Pile Foundations Based On Rocking Isolation

A new method for seismic design of bridge piers, the pile foundation design method of rocking isolation, is proposed in recent years. In this paper, through the method of the pseudo-static model test and numerical analysis to study the isolation mechanism of this device, and focus on the pile body stress distribution and variation law of the pile foundation under the vertical force and horizontal force; finding out the destruction forms and characteristics of the pile body and laying a foundation for the practical application of this kind of structure. The main research work is as follows:(1) Through consulting the literature at home and abroad, summarized the current research status of the base isolation structure and pile-soil interaction problem from the theoretical research, test methods and practical application.(2) Taking a simply supported beam bridge gravity piers based on mixed passenger and freight line as the research object, three kinds of pile foundation piers model based on rocking isolation with the ratio of 1:10 are set up. Model 1 is the free rocking isolation pier; model 2 is the seismic isolation pier model for the pier bottom slab in setting limit uplift steel; model 3 is the seismic isolation pier model of setting prestressed anti-overturning steel in the body. And the test scheme design method, model design method, loading system design method and experiment observation design method is introduced in detail.(3) Using the pseudo-static test of the model, the strain values of pile longitudinal main steel is measured and analyzed under the vertical loads and lateral cyclic loads, the distribution and change rule of the strain values of main steel is obtained. Through the comparison of the load-displacement hysteretic characteristics of each experimental model, the stress characteristics and failure mechanism of the pile foundation based on rocking isolation is further analyzed.(4) The M-method in code is applied to solve the pile’s internal force, and compared with the experimental results.(5) An analysis model of group pile foundation is established by the finite element software. The methods of soil spring simulate the elastic-plastic soil. The pile body stress and bending moment are analyzed through the comparison with model test data, to verify the rationality of the finite element analysis model.