基于管养数据的空心板底板纵向开裂原因分析

Causes of Longitudinal Cracking of Hollow Slab Based on Management and Maintenance Data

为系统的分析先张法空心板梁底板纵向裂缝的特征及成因,以桥梁管理系统的病害数据为基础,结合现场调研,总结了纵向裂纹分布特征。在此基础上从有限元数值计算的角度分析了预应力、车辆荷载、桥梁宽跨比以及底板厚度对纵向裂缝形成的影响。结果表明:纵向裂缝主要发生于预应力空心板梁桥中,并且裂缝数量、长度及宽度等特征均逐年增多增大;泊松效应及施工不当是板梁初始微裂纹产生的主要原因,也是运营期纵向裂缝产生的重要诱因,运营阶段荷载作用是导致裂纹发生并扩展的主要原因;汽车荷载作用下裂缝的扩展规律为由底板上缘向下缘扩展;宽跨比较大的桥更容易产生底板纵向裂缝;底板厚度的削弱对纵向裂缝的影响显著,且影响程度随削弱程度增加而增大。

In order to systematically analyze the features and causes of longitudinal cracks in the slab of the pre-stressed hollow slab beam,the distribution characteristics of longitudinal cracks were summarized on the basis of the disease data of bridge management system and field investigation. On the basis of the above analysis,the influence of the prestress,vehicle load,bridge width span ratio and baseplate thickness on longitudinal crack formation was analyzed from the point of view of finite element numerical calculation. The results show that the longitudinal cracks mainly occur in the prestressed hollow slab bridge,and the number,length and width of cracks increase year by year; the Poisson effect and improper construction are the main causes of the initial micro-cracks in the slab girder,and also the important inducement of the longitudinal cracks in the operation period; the main cause of the crack initiation and propagation is the load during the operation stage;under the vehicle load,the crack propagation is extended from the upper edge to the downward edge of the baseplate; the bridge with larger width-span ratio is more likely to produce longitudinal cracks in the baseplate; the weakening of the thickness of the baseplate has a significant effect on the longitudinal crack,and the influence degree increases with the increase of the weakening degree.