Theoretical And Experimental Study On The Buckling Analysis Of Piles

With the continuous development of high-pier and wide-span bridges in mountainous areas, super-long piles (especially those high-pier piles with a major unsupported length at the top) are being widely used. And the buckling analysis of pile shaft has become a complicated problem of important theoretical and engineering significance. Though many scholars at home and abroad have done extensive study work on this problem, the corresponding theoretical solutions are mostly half-analytic and obtained on the basis of the first kind of stability problem. And besides those early buckling tests directed by overseas scholars, only some elementary work has been reported at home. As for the related professional criterions or regulations, some empiric formulas have to be proposed because of the absence of reliable test data and mature computation methods. Therefore, further theoretical and experimental research on the buckling stability of pile shaft has to be performed for the perfect of professional criterions or regulations and convenient engineering application.First, according to the m-method assumption by criterions, analytical solutions for the buckling length and load of pile shaft under no axial stress, side resistance and deadweight are derived respectively by using the minimum potential energy theory and variational method. Then, unified solutions by energy method for the general exponential distribution of subgrade reaction coefficient are obtained. Based on these solutions, influence rules by side resistance, deadweight and distribution model of subgrade reaction coefficient are probed into in detail. The comparative analysis shows that, the influence by side resistance can usually be neglected, while effect by the deadweight of pile shaft can't be ignored especially when an unsupported length exists at the pile top. And the embedment proportion of pile shaft determines the influence by subgrade reaction coefficient, i.e., a larger embedment proportion causes more obvious effect. In order to consider the disadvantageous effect by those possible initial defects, the perturbation method is applied to discuss the behavior of initial post-buckling of pile shaft. And the influencing curves by the stiffness ratio of pile shaft to the surrounding soil, the length of unsupported part at the pile top, and other factors are presented as well. As the analytical solutions for buckling analysis of pile shaft by energy method are obtained according to the first kind of stability problem and can't consider some complicated factors such as the pile-soil interaction and nonlinear effect, the newly developed element-free Galerkin method (EFGM) is introduced for the first time into the field of pile foundation for buckling analysis of...