Research On Pile Group Response Under One Dimensional Seismic Loading

Pile foundation was gained widely utilization because of better economic benefit and wider applied perspective, research on pile foundation under the earthquake has obtained huge development recent years, especially, research on pile group was gained widely attention.Actually, dynamic interaction between piles in pile group had a influence of the bearing capacity of pile foundation, and affect the dynamic response of the superstructure meanwhile. Therefore, for the sake of dynamic response analysis of superstructure was made to correspond with practical situation, pile-soil interaction should be calculated in analysis. Because of vertical bearing capacity of pile foundation was reduced drastically under axial force, even appear "elastic-plastic pile" or "plastic piles".The paper break the assume condition of existing research, considered axial force in analysis.In such a premise, This paper research on the following problem with considering the pile- soil dynamic interaction:With the summarization of lots of domestic and overseas interrelated references, the domestic and overseas studying actuality and developing level on dynamic pile–soil interaction was summarized, in addition, advantages and disadvantages of existing research method on the problems was discussed likewise.Then the basic research way in this paper is introduced.Single pile in the homogeneous and elasticity soil is selected as research object.Through the analysis of single pile response characteristics under S-wave load with considering the axial force, dynamic differential equations is deduced with respect to single pile unit under S-wave.Then single pile head impendance under S-wave and axial force is deduced.Piles group dynamic response under S-wave is analysed through"4-step". Solve an equation of the wave which caused by source pile, transmitted in the soil between piles, and solve the dynamic equation of receiver pile, educe response characteristic of receiver pile, base on definition of dynamic interaction coefficients, hypothesis condition and process of equation solution, then dynamic impendance expression of piles group head is given.Utilize dynamic impendance expression of piles group head, neglect the Weight of pile cap, and assumed pile cap is completely rigid. Build a pile-soil-pile model by OpenSees. Input the P-wave, then calculate out superstructure acceleration curve and displacement curve considering pile group effect, compared to the result of traditional calculation method.The result showed that maximum acceleration of superstructure reduce 11% at least, the largest decrease reach 13.31%;maximum displacement of superstructure reduce 19.3% at least, the largest decrease reach 19.3%. Obviously, group efficiency has significant effect on response of superstructure, it should be considered in building design.