Reasearch On Laser Scanner Applied For Deformation Monitoring Of Tunnel

The construction of tunnel engineering in China has attracted worldwide attention. It's main safety risk is the stability and safety of surrounding rock.The traditional method of monitoring of surrounding rock is buried in the tunnel wall on the fixed point, using total station, gradienter,convergence instrument on measuring, so as to obtain the geometric deformation. But the disadvantages are obvious, the measurement time is long, the degree of automation is low, the remote monitoring and non-contact measurement can not be carried out, and using several sections on the cross section to replace the cross section is unreasonable, so as to monitoring the deformation of several sections to replace the whole deformation of the tunnel is unreasonable.Three dimensional laser scanning technology is a fast developing new technology. There are some advantages such as non-contact, high precision,high speed, no visible light, automatic observation and so on. Applying it to tunnel deformation monitoring can collect point information quickly and large, then establish three-dimensional model, realize the rapid monitoring of surrounding rock and improve work efficiency. So, the study of its application has realistic meaning.Firstly, this paper describes the tunnel deformation monitoring network and the classical deformation monitoring method based on it. Then, the basic principle of 3D laser scanner is introduced. Then analyze the sources of errors such as analog total station, and the error sources of 3D laser scanning technique in different operation modes. And discuss the accuracy of 3D laser scanning observation station, evaluate the deformation caused by error of observation, including mobile sighting error measurement error and site monitoring points. Through the single point positioning experiment of Trimble FX 3D laser scanner, obtain the accuracy of the single point measurement of the 3D laser scanner. The operation process of the instrument in tunnel and the principle and method of point cloud data processing are also introduced.Then, the deformation monitoring of a tunnel is carried out by means of three dimensional laser scanning method using traditional measurement methods and actual cases. The advantages and applications of the new technique in tunnel deformation monitoring are verified by comparing 3D laser scanning technique with classical methods.Finally, ground subsidence may be caused by the deformation of the tunnel excavation. The model of ground subsidence above the tunnel is established by probability integral method. The model is validated by field measurement case.