空腹式石拱桥维修加固方法及承载能力评价研究

发布时间：2018-12-13 06:58

【摘要】：随着交通量及车辆负载逐年增大,早期的石拱桥处于超负荷状态,出现各种形式的病害。作为山西省一条重要的运煤通道,国道G208交通量繁忙,而且存在严重的超载问题。由于汽车超载对桥梁的使用功能与安全功能都带来了严重隐患,因此,检测并加固存有问题的桥梁具有重要的现实意义。本文以国道G208山西运煤通道的一座空腹式石拱桥的维修加固为例,分析了该桥的主要病害,提出了针对性的加固方案;基于有限元方法进行了桥梁加固前后各个阶段的力学分析;最后基于24小时实测交通量进行了加固后桥梁的承载能力评价。研究内容集中在三个方面。第一,分析了该空腹式石拱桥的具体病害情况,确定了发生病害的内在与外在原因;提出了针对性的加固设计方案。第二,基于MIDAS有限元分析软件建立了全桥有限元模型,进行了加固各个阶段的有限元模拟分析,给出了温度以及活载作用下的桥梁结构位移值;对比了三铰拱与两铰拱在自重作用、温度荷载、重车荷载作用下的结构应力;模拟分析了三铰拱的破坏过程。第三,对比了我国与美国在桥梁承载能力评定方法上的差异;基于实测最不利车辆荷载工况,依据规范规定的荷载组合进行了桥梁腹拱的承载能力评价。研究认为,空腹式石拱桥腹拱出现下挠错位现象的内部原因在于拱顶拱铰脆弱,外部原因在于超载现象严重及冬季低温效应。基于上述两方面原因,本文提出加大立墙截面,改三铰拱为两铰拱,增厚拱圈,更换拱腹伸缩缝等结构措施,有限元分析验证该方案有效。另外,本文所研究桥梁的三铰拱拱顶铰功能已经基本失效,拱圈对拱顶的约束能力较差,在重车作用时,拱顶下挠严重。交通调查数据检验了本文主要结论。通过连续24小时的交通流调查发现,车速统计规律符合正态分布,车重的统计规律基本符合伽马分布。经计算,在最不利车辆荷载工况下,加固后的桥梁四分点和拱顶截面的承载能力满足要求。
[Abstract]:With the traffic volume and vehicle load increasing year by year, the early stone arch bridge is overloaded and various kinds of diseases occur. As an important coal transportation channel in Shanxi Province, the traffic volume of National Highway G208 is busy, and there are serious overload problems. Because the overloading of the automobile brings serious hidden trouble to the use function and safety function of the bridge, it is of great practical significance to detect and strengthen the bridge with problems. Taking the maintenance and reinforcement of a hollow stone arch bridge in Shanxi Coal Transportation Channel of National Highway G208 as an example, this paper analyzes the main diseases of the bridge and puts forward a targeted reinforcement scheme. The mechanical analysis of each stage before and after strengthening the bridge is carried out based on finite element method, and the bearing capacity of the strengthened bridge is evaluated based on the measured traffic volume of 24 hours. The research focuses on three aspects. Firstly, the concrete disease situation of the hollow stone arch bridge is analyzed, the internal and external causes of the disease are determined, and the targeted reinforcement design scheme is put forward. Secondly, based on the finite element analysis software of MIDAS, the finite element model of the whole bridge is established, and the finite element simulation analysis of each stage of reinforcement is carried out, and the displacement value of the bridge structure under the action of temperature and live load is given. The structural stress of three-hinged arch and two-hinged arch under the action of self-gravity, temperature load and heavy truck load is compared, and the failure process of three-hinged arch is simulated and analyzed. Thirdly, the difference between China and the United States in the evaluation method of bridge bearing capacity is compared, and the load-carrying capacity of the bridge web arch is evaluated according to the load combination stipulated in the code, based on the most unfavorable vehicle load conditions measured. It is considered that the internal cause of the downward deflection of the belly arch of the hollow stone arch bridge is the weakness of the arch hinge on the top of the arch, and the external reason is the serious overloading phenomenon and the effect of low temperature in winter. Based on the above two reasons, this paper puts forward some structural measures, such as enlarging the section of vertical wall, changing the three-hinge arch to two hinged arch, thickening the arch ring and replacing the expansion joint of the arch belly, etc. The finite element analysis shows that the scheme is effective. In addition, the arch hinge function of the bridge studied in this paper has basically failed, and the restraint ability of the arch ring to the vault is poor, and the deflection under the arch roof is serious when the heavy car is used. Traffic survey data test the main conclusions of this paper. Through the investigation of traffic flow for 24 hours, it is found that the law of speed statistics accords with the normal distribution, and the statistical law of vehicle weight basically accords with the distribution of gamma. Through calculation, under the most unfavorable vehicle load condition, the bearing capacity of the strengthened bridge at four points and the section of the arch roof can meet the requirements.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U445.72

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