成层地基中倾斜荷载桩改进有限杆单元法研究

传统有限杆单元法不能考虑倾斜偏心荷载下基桩的P-Δ效应,假定桩身位移为三次幂函数,结合倾斜偏心荷载下单桩受力微分方程确定的桩身弯矩、剪力与桩身水平位移关系,导得具有简洁形式、计入P-Δ效应的杆单元刚度方程,进而得到改进的有限杆单元方法,并给列出了用该法进行成层地基中倾斜偏心荷载、桩自重、水平分布荷载、竖向分布荷载和竖向分散集中荷载综合作用下并考虑桩身倾斜影响基桩内力位移分析的具体计算步骤。结合某工程实例,对上述方法进行了验证。最后对影响倾斜荷载桩的主要因素如埋深、桩材、基桩自由长度、桩身倾斜度、竖向荷载偏心矩以及荷载倾角等对基桩受力特性影响进行了分析,获得了一些定性的结论。

BEHAVIOR ANALYSIS OF PILES IN LAYERED CLAYS UNDER ECCENTRJC AND INCLINED LOADS BY IMPROVED FINITE POLE ELEMENT METHOD

The behavior of piles in layered clays under eccentric and inclined loads can not be analyzed by traditional finite pole element method if P-Δ effect is significant. To treat this problem, this paper develops the improved pole-element stiffness equation accounting for P-Δ effect, and proposes improved finite pole element method. The horizontal displacement of pile is assumed to be in the form of longitudinally cubic power function. The moment/horizontal-displacement relationship and shear/horizontal-displacement relationship are determined according to the mechanical deferential equation of piles under eccentric and inclined loads. Detail procedures to calculate displacements and internal forces of piles are presented. The accuracy of the method is demonstrated through its application in a real project. Furtherly, effects of depth, pile material, pile length above ground, pile inclination, eccentricity and inclination of loads are investigated.