郑少高速南水北调大桥辅线桥施工监控研究

发布时间：2018-09-19 13:02

【摘要】：连续刚构组合梁桥施工难度大，为了保证桥梁在施工过程中处于安全状态，主梁顺利合龙、成桥后桥梁线形与结构内力满足设计要求，对桥梁进行施工监控是非常必要的。本文以郑少高速公路与航海路连接线南水北调大桥辅线桥——大跨径预应力混凝土连续刚构组合梁桥为实例，制定了桥梁施工监控方案，实施了桥梁施工监控，并对主梁合龙关键技术进行了研究。所完成的主要工作和取得的结论有： 1．利用有限元软件Midas/Civil建立辅线桥有限元计算模型，对其施工全过程进行了模拟计算。对主要结构参数进行了敏感性分析，计算结果表明：施工过程中主梁线形受自重影响最大，混凝土弹性模量次之，预应力孔道偏差系数和孔道摩擦系数影响小。在施工中，应严格控制对结构影响较大的参数，并根据现场实际情况修正理论计算模型。 2．根据辅线桥结构特点，制定桥梁施工监控方案。基于自适应控制理论，采用以线形控制为主、应力控制为辅的原则开展桥梁施工监控工作。现场监测内容包括应力、线形和温度监测，通过对主梁各施工阶段进行实时监测，了解主梁的受力和线形，为修正计算模型和预测下一梁段受力和线形提供依据。 3．实施桥梁现场施工监控，根据现场实际情况使用最小二乘法对结构参数进行识别和调整，通过不断修正计算模型参数，准确预测和调整下一梁段立模标高，指导现场施工，使大桥顺利合龙，且在整个施工过程中桥梁处于安全状态。对比实测值与理论值可以看出：应力和线形实测值能较好吻合理论值，施工监控效果良好。 4．考虑合龙温差对中跨顶推力的影响，优化了设计顶推力，得出在一定变化范围内，顶推力、温度变化均与顺桥向位移成线性关系，进而得到温度变化与顶推力的关系。将优化后的顶推力用于指导辅线桥的顶推施工，取得较好的效果。 5．考虑不同合龙顺序对主梁受力和线形的影响，对辅线桥的合龙顺序进行了分析，结果表明：先合龙边跨再合龙中跨的方案结构压应力储备较多，利于桥梁结构后期受力，竖向挠度变化幅度和次边跨下挠较其它方案小，，尽管随着成桥时间的延长主跨下挠稍多，但可通过合理设置预拱度来解决，故辅线桥先合龙边跨再合龙中跨的主梁合龙顺序是较为合理的。 6．考虑边跨现浇段满堂支架拆除时机不同对成桥线形和结构受力的影响，对满堂支架的拆除时机进行了分析，结果表明：在边跨合龙之后中跨合龙之前拆除满堂支架，与中跨合龙后拆除满堂支架相比，桥梁结构压应力储备较丰富，成桥初期主跨上挠较多，对后期主梁线形和结构受力更为有利。
[Abstract]:The construction of continuous rigid frame composite beam bridge is difficult. In order to ensure that the bridge is in a safe state during the construction process, the main beam is closed smoothly, the alignment of the bridge and the internal force of the structure after the completion of the bridge meet the design requirements, so it is very necessary to monitor the construction of the bridge. Taking the auxiliary bridge of the South-to-North Water transfer Bridge, a long-span prestressed concrete continuous rigid frame composite girder bridge, as an example, the bridge construction monitoring scheme is established and the bridge construction monitoring is carried out in this paper. The key technology of main beam closure is studied. The main works and conclusions are as follows: 1. The finite element model of auxiliary bridge is established by using finite element software Midas/Civil, and the whole construction process is simulated. 2. The sensitivity analysis of the main structural parameters shows that the linear shape of the main beam is most affected by deadweight in the construction process, followed by the elastic modulus of concrete, and the deviation coefficient of the prestressed channel and the friction coefficient of the channel are less affected. In construction, the parameters which have a great influence on the structure should be strictly controlled, and the theoretical calculation model should be revised according to the actual situation of the site. 2. According to the structural characteristics of the auxiliary bridge, the bridge construction monitoring scheme should be formulated. Based on adaptive control theory, the principle of linear control and stress control is adopted to carry out bridge construction monitoring. Field monitoring includes stress, alignment and temperature monitoring. Through real-time monitoring of the main beam during construction, we can understand the force and shape of the main beam. This paper provides the basis for revising the calculation model and predicting the force and line shape of the next beam segment. 3. The bridge construction monitoring is carried out, and the structure parameters are identified and adjusted by using the least square method according to the actual situation in the field. By constantly modifying the calculation model parameters, accurately predicting and adjusting the elevation of the next beam section, guiding the construction on site, making the bridge close smoothly, the bridge is in a safe state during the whole construction process. By comparing the measured values with the theoretical values, it can be seen that the stress and the linear measured values are in good agreement with the theoretical values, and the construction monitoring effect is good. 4. Considering the effect of the temperature difference of the closure on the thrust of the middle span, the design of the top thrust is optimized. It is concluded that in a certain range of variations, the change of thrust and temperature is linearly related to the displacement along the bridge, and the relationship between the temperature change and the thrust is obtained. The optimized jacking thrust is used to guide the jacking construction of the auxiliary bridge, and good results are obtained. 5. Considering the influence of different closure sequence on the force and alignment of the main girder, the closure sequence of the auxiliary bridge is analyzed. The results show that the compression stress reserve of the scheme with first closing side span and then closing middle span is more favorable to the later loading of bridge structure, and the variation range of vertical deflection and the secondary span deflection are smaller than those of other schemes. Although the deflection of the main span is slightly more with the extension of the bridge completion time, it can be solved by setting the prearch reasonably. Therefore, the sequence of main girder closure of auxiliary bridge is reasonable. 6. Considering the influence of the time of removing full support in the cast-in-place section of side span on the line shape and structure force of the bridge, The time of removing the full support is analyzed. The results show that the pressure stress reserve of the bridge structure is more abundant than that of the middle span support after the middle span closure, and the full hall support is removed before the closure of the side span after the middle span closure, compared with the full house support after the middle span closure, the bridge structure has abundant compressive stress reserve. At the beginning of the bridge, there are more deflection of the main span, which is more favorable to the line shape of the main beam and the force of the structure in the later stage.
【学位授予单位】：郑州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U445.4

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