摘要
为了研究适用于车载移动测量系统的盾构隧道断面椭圆拟合方法,进而计算隧道结构检测中椭圆度和水平直径等关键分析指标,采用截尾最小二乘与选权迭代相结合的方法,首先将车载移动测量系统采集的数据进行融合解算,根据里程提取隧道断面点云,将点云(除轨道外)按角度等分为5个区域,采用截尾最小二乘法分别在各区域随机选取一点解算椭圆参数的最优初值,再利用选权迭代法逐步抑制噪声点和粗差的影响,以获得椭圆参数的最优估值。为避免局部拟合偏差过大,截取椭圆中心所在水平轴上下25 cm的区域,采用“二次曲线拟合+选权迭代”方法计算水平直径。结合工程实例,随机选取了8个隧道断面,回归统计分析表明椭圆拟合精度达0.9以上;将水平直径的拟合值与设计值进行对比,验证了水平直径相对变形值均小于3‰。实验结果表明,“截尾最小二乘+选权迭代”和“二次曲线拟合+选权迭代”方法可有效抑制盾构隧道断面点云中噪声与粗差的影响,获得高精度的椭圆参数和水平直径。
In order to investigate the ellipse fitting algorithm of shield tunnel section with vehicle-borne mobile measurement system and calculate key indexes such as ellipticity and horizontal diameter of tunnel structure,the method which combine least trimmed squares with weight iteration is adopted.Firstly,the data collected by the vehicle-borne mobile measurement system is calculated jointly,and the point cloud of the tunnel sections could be extracted by mileage.After that,the point cloud,which does not included railway track,is equally divided into 5 regions according to the Angle.One point is selected randomly in each region to calculate the optimal solution by using the least trimmed squares,and take it as the initial value of the ellipse parameter.Selecting weight iteration algorithm is used to gradually suppress effects of noise and gross errors to get the optimal estimation of ellipse parameters.In order to avoid excessive local fitting deviation,an area within 25 cm above and below the horizontal axis of the center of the ellipse is located,and the algorithm of conic fitting combined with weight iteration is adopted to calculate the horizontal diameter.In course of an engineering project,eight tunnel sections were randomly selected.The regression statistical analysis shows that the accuracy of ellipse fitting is more than 0.9.By comparing the fitted values of horizontal diameter with the design values,it is verified that the relative deformation is less than 3‰.The results show that the method can effectively suppress effects of noise and gross errors in the point cloud of the shield tunnel sections,and obtain high-precision ellipse parameters and horizontal diameter.
作者
巩健
Gong Jian(China Railway Design Corporation,Tianjin 300251,China)
出处
《铁道勘察》
2020年第6期33-38,共6页
Railway Investigation and Surveying
基金
中国铁路设计集团有限公司科技研究计划重点课题(2019YY320205)。
关键词
激光点云
椭圆拟合
椭圆度
截尾最小二乘
选权迭代
laser point cloud
ellipse fitting
ellipticity
least trimmed squares
selecting weight iteration
