基于磁场梯度张量的斜拉桥拉索断丝监测方法  

Wire breakage monitoring method for cable-stayed bridge cable using magnetic gradient tensor

作　　者：江胜华[1] 孙伟贺 王浩 刘晓春[2] JIANG Sheng-hua;SUN Wei-he;WANG Hao;LIU Xiao-chun(College of Engineering and Technology,Southwest University,Chongqing 400715,China;School of Civil Engineering,Central South University,Changsha 410075,Hunan,China)

机构地区：[1]西南大学工程技术学院,重庆400715 [2]中南大学土木工程学院,湖南长沙410075

出　　处：《长安大学学报（自然科学版）》2022年第4期52-62,共11页Journal of Chang’an University(Natural Science Edition)

基　　金：国家自然科学基金项目(51208078);重庆市基础与前沿研究计划项目(cstc2015jcyjA30008);重庆市技术创新与应用示范(社会民生类)项目(cstc2018jscx-msybX0028)。

摘　　要：为研究斜拉桥拉索断丝位置及数量的监测方法,排除环境磁场的干扰,提出基于磁场梯度张量的斜拉桥拉索断丝监测方法。研制拉索断丝监测试验装置,包括磁场传感系统和运动控制系统,运动控制装置采用铝合金、铜连接件等非磁性材料装配,极大程度上消除试验装置中的磁场干扰。分析单根钢丝及整束拉索钢丝断丝前后的磁感应强度、磁场梯度及局部模量等磁场特征的变化规律,研究整束拉索的磁场梯度及局部模量与断丝数量的关系。试验结果表明:对于单根钢丝,环境的磁感应强度与钢丝的比值为98.47%~157.76%,环境磁感应强度的影响不可忽略。环境的磁场梯度及局部模量与单根钢丝的比值为3.34%~6.67%,远小于钢丝自身的磁场梯度及局部模量,可忽略不计。单根钢丝及整束拉索钢丝出现断丝时,磁场梯度及局部模量的曲线在断丝处发生突变,出现波峰和波谷等。断丝数量与波峰(或波谷)的深度、宽度及曲线突变处包围的面积等特征参数相关。通过磁场特征参数测得断丝位置在300.75 mm,与实际断丝位置300 mm相比,误差为0.25%;相较于1根断丝,2根断丝时波峰(或波谷)的深度平均值与其比值为1.82;波峰(或波谷)的宽度平均值与其比值为1.07;突变处包围的面积平均值与其比值为1.95。突变处包围的面积作为断丝数量的评估指标更为有效。In order to study the monitoring method of location and number of cable wire breakage for cable-stayed bridge and eliminate the interference of environmental magnetic field,the monitoring method of wire breakage based on magnetic gradient tensor was proposed.The monitoring device for wire breakage was developed,including magnetic field sensing system and motion control system.The motion control device was assembled with non-magnetic materials such as aluminum alloy and copper connector,so as to eliminate magnetic interference in the experimental device to a great extent.The magnetic field intensity,magnetic gradient and partial modulus were analyzed for a single cable wire and a bundle of cable wire before and after wire breakage.The relationship between the magnetic gradient,partial modulus and the number of broken wires was studied.The results show that the ratio of environmental magnetic field intensity to single cable wire’s magnetic field intensity is 98.47%to 157.76%,so the influence of environmental magnetic field intensity cannot be ignored.The ratio of environmental magnetic gradient(partial modulus)to single cable wire’s is 3.34%to 6.67%,so it can be ignored.The environmental magnetic gradient and partial modulus are far less than those of the cable wire.When a single wire and a whole bundle of cable wire are broken,the magnetic gradient and partial modulus curves change suddenly at the broken region,including crest or trough,etc.The number of broken wires in the whole bundle of cables is related to the magnetic characteristic parameters such as the depth and width of curve crest(or trough)and the area surrounded by abrupt changes.Location of wire breakage measured by magnetic characteristic parameters is 300.75 mm,and the error is 0.25%compared with the actual location of wire breakage of 300 mm.Compared two broken wires with one broken wire,the ratio of crest or trough’s average depth is 1.82,the ratio of crest or trough’s average width is 1.07,the ratio of average area surrounded by the mutat

关 键 词：桥梁工程 斜拉桥 断丝 监测 磁场梯度张量 断丝位置 断丝数量 

分 类 号：U448.27[建筑科学—桥梁与隧道工程]