基于弧形搭板的桥头跳车处治机理

The Treatment Mechanism of Vehicle Bumping at Bridgehead Based on Arc Slab

本文为解决路桥过渡段不均匀沉降引起的桥头跳车问题,首先,建立了一端固定、一端自由的弧形搭板力学分析模型,推导了弧形搭板挠度方程,求解出仅考虑法向地基反力和同时考虑法向、切向地基反力两种情形下的解析解;其次,建立了基于Drucker-Prager土体本构关系的三维有限元模型,对比分析了弧形搭板与传统矩形搭板不均匀沉降;最后,在实际工程中验证了弧形搭板的可行性,将解析解、数值解与工程实测值进行比较。结果表明:弧形搭板挠度从固定端处的0平稳增大至自由端处的最大值,仅考虑法向地基反力和同时考虑法向、切向地基反力两种情形下挠度最大值分别为3.41,3.02 cm。弧形搭板沉降值比矩形搭板更小,最大差值处两者沉降值分别为1.94,3.43 cm。实际工程竣工一年后弧形搭板中部位置沉降仅为3.03 cm,自由端处最大沉降为4.35 cm,对应纵坡变化率为0.54%,符合相应规范要求,弧形搭板可为解决桥头跳车问题提供参考。

In order to solve problem of the vehicle bumping at bridgehead which caused by uneven settlement of bridge transition section.Firstly,a mechanical analysis model of arc slab with one fixed end and one free end was established,the deflection equation of arc slab was derived.The analytical solution was obtained for the two cases of considering only normal foundation reaction force and both normal and tangential foundation reaction force.Secondly,a three-dimensional finite element model based on the Drucke-Prager principal structure relationship was established,the uneven settlement of the arc slab and the traditional rectangular slab were compared and analyzed.Finally,the feasibility of arc slab was verified in the practical project,the analytical and numerical solutions were compared with the measured values of the project.The results show that the deflection of arc slab rises smoothly from 0 at the fixed end to the maximum value at the free end.The maximum values of deflection are 3.41 cm and 3.02 cm for the two cases of considering only normal foundation reaction force and both normal and tangential foundation reaction force.The settlement of arc slab is smaller than that of the rectangular slab.The maximum difference between two settlement values are 1.94 cm and 3.43 cm,respectively.The practical project has been completed one year later,the settlement in the middle of arc slab was only 3.03 cm,and the maximum settlement at the free end was 4.35 cm,corresponding to a longitudinal slope change rate of 0.54%,which was in line with the corresponding specification requirements,and the arc slab could provide a reference for solving the problem of bumping traffic at the bridge head.