基于桥面形态变化的桥梁安全状态监测方法与预警理论研究

The artificial visual inspection of bridge which is the most common method of bridge regular safety inspection in the practical operation is lack of quantitative scientific basis. It is difficult to find the hidden danger of the bridge structure and led to frequent collapse of the bridge in recent years. In order to grasp the safety status of the bridge and prevent the bridge accident, the purpose of this project is to find a bridge safety monitoring method and early warning theory which is more efficient, accurate and quantifiable than traditional artificial inspection. Mobile three-dimensional laser scanning system is used to get the data of deck shape change under the constant load of bridge. Identification method of deck shape feature based on corresponding bridge structure safety is studied to establish the corresponding geometric model of the discrete surface data of bridge deck. The noise data of local damage of deck pavement and the data of deck shape change caused by temperature are separated to analyze the variation of deck shape data with the bridge structure stiffness. According to the discontinuous character of surface shape and the global or local deformation character of deck shape, the bridge safety monitoring method and early warning theory based on the change of deck will be established. The results of the research can provide the quantitative basis for bridge regular safety inspection and can provide the objective historical experience data. It can lay the theoretical and applied foundation for early warning theory.

桥梁的经常性安全检查在实际操作上多体现为养护人员对桥梁的人工视觉巡查，缺乏可量化的科学依据，难以及时发现桥梁结构安全隐患，致近年来桥梁坍塌事故逐趋频发。为掌握桥梁安全状态，预防灾害事故发生，本项目旨在寻找一种相比传统人工经常性巡检更高效、准确、可量化的桥梁安全状态监测方法和预警理论。拟以移动式三维激光扫描技术为测量载体，依据桥梁恒载效应下的桥面形态变化数据，以桥梁结构安全对应的桥面形态特征因子识别方法为研究对象，建立相应的桥面离散曲面数据几何特性估算模型，分离桥面铺装局部破损噪声信息和温度引起的桥面形态变化，分析桥面形态变化数据随桥梁结构刚度演化规律，依据面形不连续特征结合桥面整体/局部变形形状特征，建立基于桥面形态变化的桥梁安全状态监测方法与预警理论。研究成果可为桥梁经常性安全检查提供量化依据和客观历史经验数据支持，为基于桥面形态变化的桥梁安全状态预警方法奠定理论和应用基础。

桥梁的经常性安全巡检目前大多采用的是人工目测打分评估的形式，其有效性极大程度上依赖于维护管养工人的专业素质。为寻找一种相比人工经常性巡检更高效、客观、量化的人工安全巡检替代方法，智慧化感知桥梁安全状态，预防灾害事故发生。本项目从桥梁结构扰度、转角与曲率理论关系出发，定义各单元面积的平方与所有单元面积平方和的比值为“曲率面积差参数（ADk）”，该值产生突变的位置即表征了前后工况结构发生损伤的位置。进而基于薄板变形理论，推导了桥梁挠曲面的高斯曲率与结构刚度之间的理论关系，论证了桥梁挠曲面高斯曲率变化对结构刚度变化的敏感性，提出挠曲面考查点高斯曲率的计算方法。基于“曲率面积单元方差比”对模型桥进行了有效的损伤识别验证，同时分析了曲率面积计算单元长度对识别效果的影响；对损伤前后的挠曲面进行叠差分析得到挠度变化云图，再计算桥面单元特征点挠度变化的高斯曲率值，基于高斯曲率值的突变性对模型桥进行了有效的损伤识别验证。基于上述结果，本项目的研究为高效量化的桥梁结构损伤识别探索了一条新途径。