三维激光扫描技术在隧道管片加载试验中的应用

Application of 3D Laser Scanning Technology in Ultimate Load-Bearing Capacity Test of Shield Tunnel

以复合腔体加固前后的盾构隧道衬砌1∶1圆环为对象,采用三维激光扫描技术对加载试验中同一管片在原型状态、加固临界点状态及复合腔体与管片黏结失效状态下的管片进行扫描。通过对比试验中不同阶段的扫描数据,从管片变形、接缝张开、管片裂缝等角度计算分析管片结构关键节点的变形情况与对应内力关系。抛弃了传统的基于变形点以点代面的分析方式,选择基于整体监测对象进行形变分析的方法,并通过“切片法”提取三期点云相同位置断面进行形变定量分析。试验数据表明相对于未加固阶段,加固后的结构整体变形量平均分布在20 mm上下,变形增幅并不明显,证实了复合腔体加固方法可有效遏制未加固隧道的变形。结合结构力学数据,该实验结果可作为进行深入数值分析的基础。

Taking the 1∶1 ring of shield tunnel lining before and after the composite cavity reinforcement as the object,the 3D laser scanning technology is applied in ultimate load-bearing capacity test of deformed segmental tunnel linings strengthened by composite cavity to study deformation of tunnel segment during the whole loading process.By analyzing three point clouds obtained under key performance status,namely initial state,reinforce-ment critical point state,and bonding failure between composite cavity and segment,displacement、extending of joints and crack width of the structure under key performance point are considered as parameters to study the relationship between load and deformation of tunnel.A method for deformation analysis based on the overall point clouds instead of individual points is applied to deformation monitoring of the segment,furtherly deforma-tion analysis of three-period section data extracted with point cloud slicing method is conducted.This experi-mental result shows that compared with the unreinforced stage,the overall deformation of the reinforced struc-ture is evenly distributed around 20 mm in slow growth mode,proves that the composite cavity reinforcement method can effectively contain the deformation of the unreinforced tunnel and provides basis for in-depth nu-merical analysis combined with the structural mechanics data.