高墩-群桩体系临界荷载计算

Critical Load Calculation of High-pier and Pile Groups System

考虑桩-土相互作用对上部高桥墩稳定性的影响,基于力效相等原则,通过力法原理,将群桩基础进行等代以模拟桩土作用,导出了单肢高墩-群桩体系在竖向荷载作用下的屈曲临界荷载计算公式.通过工程实例验证了本文方法的可行性,分析了桥墩刚度和高度对体系稳定性的影响.结果表明:桥墩的刚度和高度是影响体系屈曲性能的两个重要因素,但当墩高及其刚度值超过某一界值,体系的临界荷载趋于一定值,即结构的屈曲破坏不是一个材料破坏的问题,而是体系存在一最优墩桩刚度比和长度比,使得墩-桩-土三者共同工作最协调.

Aiming at the effect of piles-soil interaction on high pier stability, this paper, based on the equal forceeffect principle, substituted pile foundation to a ＂pier-style ＋ level spring＂ mode to simulate that effect, then a critical load calculation method considering the pier- piles-soil system under the vertical load was developed. And to validate the method proposed, an engineering example was illustrated. The calculation results have shown that this method is reasonable. Finally, based on the example and formula, the effect of pier stiffness and height changes on the system stability was analyzed, and the results have shown that the pier stiffness and height are two important performances to the system. Structure buckling is not a material damage problem, but has an optimal stiffness and length ratio in high pier and pile founda- tion system, which makes every part of the structure work in coordination.