考虑桩-梁协调作用的桩基托梁计算理论分析

Theoretical Analysis of Calculation of Pile Foundation Joist on Consideration of Pile-beam Coordination Interaction

研究目的:桩基托梁结构目前在铁路中广泛被使用,其内力设计计算忽略桩与托梁的协调作用,将托梁所受荷载考虑成均匀分布不准确,也比较保守。本文建立同时考虑桩与托梁共同受力的力学模型,推导出方便设计的计算公式和具体求解过程,以使托梁结构得内力计算更准确。研究结论:(1)托梁荷载分布应由均匀分布改为马鞍形或梯形分布模式,托梁应考虑桩基础协同作用来计算内力;(2)托梁跨中弯矩值有所降低,以文中计算为例,减小近40%,剪力则变化很小;(3)基于传统计算模型设计的托梁尺寸、配筋应进一步优化。

Research purposes： The pile foundation joist structure is widely used in the railway construction currently, but the coordination interaction between the pile and the joist is ignored in calculation of the internal force of the pile foundation joist. Regarding the load born by the joist as even distribution is not exact and is rather a conservative. This paper presents a mechanics model on consideration of joint bearing load of the pile and joist. With this model, the computation formula convenient for design and the concrete solution procedure can be deduced to make calculation of the internal force of the joist structure more exact. Research conclusions：（ 1 ）The joist load distribution should be changed from the even distribution into the saddle - shaped distribution or ladder - shaped distribution. The coordinated effect of the pile foundation should be taken into account in calculation of the internal force for the joist. （2） Taking the calculation presented in this paper, the bending moment value in the span of the joist decreases by about 40% while the variation of the shear force is small. （3） The size and the reinforcement of the joist designed with the traditional calculation model should be further optimized.