摘要
公路下穿铁路,在地下水位较高时通常采用封闭式路堑U型槽结构。封闭式路堑是一种由边墙和底板组成的结构,它与桥(或涵)构成为一个整体,将地下水封闭在墙后及底板之下。
本文首先总结和分析了封闭式路堑U型槽结构设计的原则、方法和具体的设计计算内容,指出了设计中应注意的问题,然后结合具体工程的地质、水文情况介绍封闭式路堑U型槽结构边墙设计方法。边墙按悬臂梁计算,底板计算按弹性地基梁理论计算。同时利用ANSYS10.0软件进行分析,采用分离式模型:混凝土(solid65)+钢筋(link8),认为钢筋混凝土间粘结力足够好,网格按自由划分,验证结构设计满足承载力要求。
With the booming economy, rapid construction of infrastructure, a large number of railway, highway overpass to the Cross, some route to the inevitable way of cutting through the groundwater beneath the site level was high, in order to ensure speed and security, the use of closed road cutting U-shape structural. It is a composition by the wall and floor structures with culvert constitute a whole, will be closed to ground water under the floor. It not only can reduce the water table but also ensure stable cutting drying, and has a simple structure, convenient for construction. However, unlike the structure of retaining wall and other forms of applications so wide that there is no uniform industry standard. This paper summarized the results of existing theory and examples of actual projects, theoretically analyzed and discussed the structure design of the U-shape structural.
This paper summarizes and analyzes the principles, methods and content of the specific design and calculation of closed road cutting U-shape structural design, that the design should pay attention to the problem, then describes the design of a closed cutting U-shape structural wall combine the specific engineering geology and hydrology. Side wall is mainly affected by soil pressure, soil pressure calculation used Coulomb earth pressure, the bottom of wall is affected the biggest force, and calculated the maximum bending moment for reinforcement and checked the crack width whether to meet the requirements. Bottom slab calculate with elastic foundation beam theory, and analysis use ANSYS10.0 software and take separate models: Concrete (solid65) + bar (link8), that the bond strength between concrete and reinforcing steel bar is good enough, free elections division of the grid, analysis whether the result of structural design to meet the capacity requirement.
The following conclusions of this paper:
1. Behind the side wall of U-shape structure, Earth pressure used in this project consistent with the actual situation.
2. Both the result of calculation of U-groove and the usage of project show that the section form, wall top width is 0.5m, back slope ratio is 1:0.15 and the thickness of the bottom beam is 0.1 times its length are more reasonable.
3. By finite element simulation, the maximum displacement value of the structure and cracks can meet the requirement. The analysis show that this structure force is basically right and bottom calculation with elastic foundation beam method basically consistent with the actual situation, the structure of closed road cutting U-shape obtained by calculating the reinforcement can meet bearing capacity and deformation demands.
In the last of this paper, put forward to the future research directions of closed road cutting U-shape structure and make several suggestions. First, calculation of earth pressure is a very complex issue, this calculation is based on triangular distribution, simplify the calculation, and the actual distribution does not meet the curve, need further study. Second, if the earth with water, many problems have become complex, now there is no unified conclusion, the circumstances require further study. Finally, U-shape structural side wall is calculated by retaining walls, bottom slab is calculated by elastic foundation beam method, the actual side wall and bottom slab are poured as a whole, they can support each other, this did not take into account the results of the entire cast of the beneficial effects, which will make the force is more large, need further study.
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