基于统一边界和梁格模型的整体式桥台桥梁分析

Analysis of an Integral Abutment Bridge Based on Unified Boundary Condition and Grillage Model

摘要:

取消伸缩缝及支座的整体式桥台桥梁可以避免伸缩缝的病害及对行车的影响。由于桥台处的上部结构与下部结构浇筑在一起，整体式桥台桥梁的上部结构受力受到下部结构乃至土体的影响，使其计算需要将上下部结构综合考虑，计算方法也更为复杂。提出一种思路，以实现上部结构在不同荷载作用组合下的验算与调整。以一座两跨的整体式桥台桥梁为依托工程，通过实体有限元模型在代表性工况下提取边界条件，施加到全桥的梁格模型中，完成整体式桥台桥梁的计算与设计，具体流程如下：在实体有限元模型中，建立简化的“单梁+单桩”模型，并采用以“m”法确定刚度的土弹簧模拟结构-土相互作用；计算模型整体升温下的梁端轴力和形心处线位移及跨中加载下梁端弯矩及角位移，换算成2个具有一定距离的线弹簧，作为边界条件施加在全桥的梁格模型上。在梁格模型中，得到全桥在多种工况下的内力及承载力结果，完成对整体式桥台桥梁的设计。在非岩石类地基中，当结构-土相互作用采用“m”法模拟时，简化手段与设计方法的可行性得到了验证。

关键词:整体式桥台桥梁;“m”法;“单梁+单桩”模型;边界条件;梁格模型

Abstract:

Without expansion joints and bearings， integral abutment bridges can avoid the disease of expansion joints and the impact on driving. Since the superstructure and the substructure at the abutment are poured together， the force of the superstructure of integral abutment bridge is affected by the substructure and the soil， the calculation requires comprehensive consideration of the superstructure and the substructure， and the calculation method is more complex. The author proposes a new idea to realize the verification and adjustment of the superstructure under different load combinations. In this paper， a two-span integral abutment bridge is used as a supporting project， the boundary conditions are extracted under representative working conditions through a solid finite element model and applied to the grillage model of the full bridge， then we can complete the calculation and design of the integral abutment bridge， the specific process is as follows： In the solid finite element model， establish a simplified "single beam + single pile" model， and use the "m" method to determine the stiffness of the soil spring to simulate the structure-soil interaction； calculate the axial force and the linear displacement at the centroid of the beam end under the overall heating condition， and the bending moment and angular displacement at the beam end under mid-span loading condition， then convert them into two linear springs with a certain distance， which are applied to the grillage model of the full bridge as a boundary condition. In the grillage model， the internal force and bearing capacity of the full bridge under various working conditions are obtained， then the design of the integral abutment bridge is completed. In non-rock foundations， when the structure-soil interaction is simulated by the "m" method， the feasibility of the simplification and the design method has been verified.

Key words:integral abutment bridge;“m” method;“single beam+ single pile” model;boundary condition;grillage model