Research On Vibration Characteristics Of Pile Foundation In Liquefied Soil

With the development of the high-rise building and the frequent occurrence of earthquakes, the analysis of liquefied soil in the pile-soil interaction becomes very difficult. The vibration characteristics of the pile in the liquefied soil, more attention has been got from the engineering industry. The liquefaction judgment of soil in code for seismic design of buildings, and carrying capacity of pile foundations in liquefied soil were analyzed and summarized. And engineering examples are used to explain it. Nonlinear p-y curve method is used to investigate the nonlinear vibration characteristics of pile foundations. the failure mechanism of pile in liquefied soil make a summary, Combined with the destructive instance, The destructive theory of pile in liquefied soil made a demonstration (such as buckling unstable theory). Chaotic behavior of nonlinear rock-socketed pile in axial vibration is analysised by the analytic prediction method, using the Melnikov function and the Galerkin method. Predecessors in the theory of nonlinear science (such as catastrophe theory, etc.) get the formulas of a variety of the super-long piles of dynamic unstable analysis to summarize, compare and analyze. Especially it combine liquefaction Projects, and the change of liquefied and liquefaction sand parameters (such as lateral friction and pile lateral soil resistance). The destructive modes of buckling instability and the instability of pile in liquefiable soil are discussed.Following aspects are included in this research contents:1.The liquefaction judgment of soil in new and old code for seismic design of buildings, and carrying capacity of pile foundations in liquefied soil were analyzed and summarized. And engineering examples are used to explain it. Liquefaction effects of technical code for building pile foundations are also discussed; it gives that rationality of new standard, and puts forward a bit of advice,which should be adopted to seismic design method of pile foundation in liquefied soil.2.Writing partial differential equations of the pile foundation linear axial vibration, in the given boundary conditions,and it gets the expressions of the vibration modes of and natural frequency of the linear viscoelastic pile foundation, drawing schedule curve of liquefaction, before and after viscous linear system, some conclusions are drawn;it also gives partial differential equations when pile axial vibration nonlinear and the conditions about the homoclinic orbits and heteroclinic orbits, Summed up the parametric equation of the homoclinic orbit, then give an analytic prediction formula of chaotic vibration.3. For shaking table tests, dynamic centrifuge tests, other model tests and test data and results were reviewed, analyzed and summarized. P-y curve based on the test and the p-y curves to be calculated by the static method and coefficient reduction method were analyzed. The rationality and applicability where p-y curve in liquefied soil conditions used pile dynamic response analysis of the specification are explored.4. Combined with the recent decades at home and abroad to earthquake damage survey, and destruction mechanism of pile has been analyzed, it is mainly to study the failure mechanism of pile’s buckling instability; combined with project instance in liquefaction, summarize and analysis a variety of formulas of the super-long piles of dynamic stability analysis using nonlinear scientific theories, discuss the buckling of the pile foundation in liquefied soil instability and pile in stability failure modes combined liquefied before and after sand parameters (such as lateral friction and pile-side soil resistance) changes.