喷射高性能水泥复合混凝土加固石拱桥承载力试验研究

发布时间：2018-08-03 22:00

【摘要】：石拱桥在我国历史悠久，有着造型优美、造价低廉、取材方便、技术娴熟等优点。建国初期石拱桥曾得到广泛应用，在我国交通建设和发展历史上发挥着极其重要的作用。然而由于年久失修、交通量加重、自然灾害等原因，大部分石拱桥目前存在一定的开裂、破损等安全隐患。考虑到旧危桥数量多，覆盖面广，拆除重建不仅耗资巨大，新建期间社会付出的“综合代价”更为高昂，因此对旧危桥进行加固重利用是最佳选择。高性能水泥复合混凝土加固技术是一种新型的加固方法，能有效提高构件的抗压、抗弯承载力及整体性能，有效控制结构裂缝开展，，正被广泛应用于砌体和混凝土加固领域。高性能水泥复合混凝土加固技术较其他桥梁加固技术相比，具有施工方便快捷，经济效益好，无机材料加固耐久性好等优点。用高性能水泥复合混凝土加固石拱桥，能免去上部填土开挖，大大减少工程量，具有重要的社会和工程意义。为了研究喷射高性能水泥复合混凝土加固石拱桥的加固效果，在湖南大学结构实验室中砌筑两相同模型拱桥，一座不加固，一座考虑到石拱桥通常具有较大的恒载不能卸除，在加载到破坏荷载的70%时持载做带载加固试验。通过试验结果的对比分析，研究喷射高性能水泥复合混凝土加固后对石拱桥开裂模式、破坏形态及极限承载力的影响。实验结果表明：未加固拱桥模型极限承载力为800kN,在达到破坏荷载70%时持载喷射60mm厚高性能水泥复合混凝土加固的拱桥模型极限承载力为1000kN,承载力提升幅度为25%，喷射高性能水泥复合混凝土能有效提高拱桥的承载力。未加固拱桥模型在加载至破坏荷载95%时，在破坏位置拱侧面迅速出现一条沿拱轴线方向的贯通裂缝，在裂缝出现后很短时间内破坏，基本没有反应时间，破坏呈明显脆性。加固后拱桥模型在加载至极限承载力90%时，在破坏位置拱侧面已有明显沿拱轴线方向的裂缝，有一定的破坏征兆，说明喷射高性能水泥复合混凝土能有效改善拱桥模型的脆性破坏特性。加载过程中加固层与拱桥模型粘结良好，无剥离及滑移现象。破坏后拱桥模型仍保持相当的整体性，说明加固层能有效的加强拱桥模型的整体性。最后，本文结合试验和理论分析，提出了对加固后拱桥模型承载力计算方法。计算结果与试验结果吻合良好，可供加固设计时参考使用。
[Abstract]:Stone arch bridge has a long history in our country. It has the advantages of beautiful shape, low cost, convenient material selection and skillful technology. Stone arch bridge was widely used in the early years of the founding of the people's Republic of China and played an extremely important role in the history of traffic construction and development in China. However, due to years of disrepair, increased traffic volume, natural disasters and other reasons, most of the existing stone arch bridges have some safety risks such as cracking and breakage. Considering the large number and wide coverage of old dangerous bridges, demolition and reconstruction not only cost a lot, but also the "comprehensive cost" paid by the society during the new construction period, so strengthening and reusing the old dangerous bridges is the best choice. High performance cement composite concrete (HPC) is a new reinforcement method, which can effectively improve the compressive capacity, flexural bearing capacity and integral performance of the members, and effectively control the crack development of the structure. It is widely used in masonry and concrete reinforcement fields. Compared with other bridge strengthening technology, high performance cement composite concrete reinforcement technology has the advantages of convenient construction, good economic benefit and good durability of inorganic materials. It is of great social and engineering significance to reinforce the stone arch bridge with high performance cement composite concrete, which can avoid the excavation of the upper fill and greatly reduce the amount of construction work. In order to study the strengthening effect of stone arch bridge strengthened by shotcrete high performance cement composite concrete, two same model arch bridges are built in the laboratory of Hunan University structure, one arch bridge is not strengthened, the other is that stone arch bridge usually has large dead load that can not be removed. When loading to 70% of the failure load, the loading is carried out with load reinforcement test. Through the comparison and analysis of the test results, the effects of shotcrete reinforced high performance cement composite concrete on the cracking mode, failure form and ultimate bearing capacity of the stone arch bridge are studied. The experimental results show that the ultimate bearing capacity of unreinforced arch bridge model is 800kN, and the ultimate bearing capacity of unreinforced arch bridge model is 1000kNwhen the failure load is 70kN. The ultimate bearing capacity of arch bridge model strengthened with 60mm thick and high performance cement composite concrete is 1000kN. High performance cement composite concrete can effectively improve the bearing capacity of arch bridge. When the model of unreinforced arch bridge is loaded to failure load 95, a through crack along the axis of arch appears rapidly in the failure position of the arch, and it is destroyed in a short time after the crack appears, and basically has no reaction time, and the damage is obviously brittle. When the model of the strengthened arch bridge is loaded to the ultimate bearing capacity 90, there are obvious cracks along the axis of the arch in the failure position of the arch side, and there are certain signs of failure. The results show that shotcreting high performance cement composite concrete can effectively improve the brittle failure characteristics of arch bridge model. During the loading process, the strengthened layer bonded well with the arch bridge model, and there was no peeling and slip phenomenon. After failure, the arch bridge model still maintains a considerable integrity, indicating that the strengthened layer can effectively strengthen the integrity of the arch bridge model. Finally, combined with experimental and theoretical analysis, this paper puts forward a method for calculating the bearing capacity of reinforced arch bridge model. The calculated results are in good agreement with the experimental results and can be used for reference in reinforcement design.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U445.72;U446

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