Study Of Tunnel Deformation Monitoring Based On Close-Range Photogrammetry Technology And Three-Dimensional Laser Scanning Technology

With the rapid development of construction industry,our country has increased investment into underground construction.A large number of tunnel projects have emerged,and tunnel accidents are not uncommon.For tunnel engineering construction,regardless of in the construction stage and operation stage,the stability of tunnel is an important factor affecting its safety.The loss of stability of the tunnel structure will endanger the safety of life and property.Therefore,real-time deformation data can be obtained by the regular and effective deformation monitoring which can guarantee the stability of the tunnel.Only in this way,can relevant sections be provided with warnings to facilitate early repair of tunnel or take other protective measures,and the deformation of the tunnel endangering life safety can be avoided.There are a series of problems like low working efficiency and environmental impact in traditional tunnel deformation monitoring methods.As new surveying and mapping technologies,close range photogrammetry and 3d laser scanning with advantages of not contacting the target object,high efficiency and access to large amount of data,have been widely applied in the fields of spatial information acquisition,the reparation of ancient architectural structures and restoration project safety inspection.The application of 3d laser scanning technology and the close range photogrammetry technology into deformation monitoring of tunnel can not only reconstruct the 3d modeling of tunnel,but also improve the accuracy of measurement of tunnel internal monitoring.This paper analyzed the feasibility of the introduction of 3d laser scanning technology and close range photogrammetry technology into the deformation monitoring of tunnel by experiments,constructed three dimensional tunnel model based on 3d laser scanning technology and close range photogrammetry technology,and analyzed the accuracy of the 3d laser scanning technology and the close shot photogrammetry technology in the tunnel deformation monitoring by comparing the two monitoring stations in the tunnel model variation with total station measuring the difference between true value.The conclusions are as follows:1.By using multi-baseline digital close range photogrammetric system platform to calibrate the non metric digital camera Canon 5D Mark?,camera calibration parameters are obtained by using the method of semi-automatic model matching.The results show that the camera calibration method based on Lensphoto can be used in close shot photogrammetry in tunnel deformation monitoring.2.The working principle and process of 3d laser scanner are elaborated and the parameters of the 3d laser scanner Z + F IMAGER 5010 c introduced simply.By adjusting the target number and position of the target in the experiment of model connecting,it is concluded that when the target number is 3,the model precision is the highest and the smaller the angle of target center line crossing with scanner center line is,the precision is higher.3.Point cloud data and digital images inside the tunnel can be obtained by using a non metric digital camera and a 3D laser scanner to scan and shoot the inner part of tunnel twice.Using Lensphoto and Lasercontrol to calibrate and match the point cloud data and digital video image,finally a three-dimensional model inside of the tunnel can be acquired.4.Extract the coordinates of the monitoring points in the 3D model of close range photogrammetry and 3D laser scanning measurement,calculate the offset of two monitoring points by the two methods,and compare the precision gotten by applying close range photogrammetry and 3D laser scanning measuring into tunnel deformation monitoring based on observational data as the true value by using 0.5 "level measurement robot tm30.Finally,it is concluded that errors in all monitoring points x,y,z direction and positions are controlled between ±11.2 mm by two methods,which can meet the needs of the tunnel deformation monitoring.At the same time,precision of 3D laser scanning technology is significantly higher than that of the accuracy of close range photogrammetry.