Research On The Tunnel Deformation Monitoring Based On The Ordinary Digital Camera

The safety and stability of the tunnel engineering structure is always the most priority during its construction period and operation state. The existence of the tunnel deformation caused by some external and internal factors has been evidenced in the field and rushed the tunnel normal operation into a safety-and-stability-threatening risk. Hence, the process of tunnel deformation monitoring worth a lot in the tunnel engineering application: grasp the tunnel situation and detect its defects in time, build and deploy the solution of tunnel defect cure in advance, put out the possibility of tunnel accidents intentionally.In recent years, photography measurement technology is raising more and more practical attention.This method has several advantages such as easily handled equipment, indirectly measurement, rapid data acquisition, with a higher automation. Since the digital close-range photogrammetry technology and ordinary digital camera resolution is upgrading themselves all the time, the ordinary digital cameras are at handy and taking a bigger place in close-range photogrammetry applications. Based on the deficiency of using the traditional deformation measurement method in the tunnel build-in operation and the previous researchers’work, this paper introduces the digital close-range photogrammetry technology, which is implemented by the ordinary digital camera, into the tunnel deformation monitoring application. This paper has also presented the feasibility of utilizing non-metric digital camera to measure tunnel deformation in limited conditions and narrow space. Finally, the paper has completed the implement of the corresponding tunnel deformation monitoring system. The main research contents of this paper are as following:(1) Design and build the outdoor three-dimensions control field. The control field site is chosen in the tunnel port exit. The coordinate of the control points is obtained from the total station. The measuring method is the completely free station method.(2) Calibrate the ordinary digital camera in the control field that has been mentioned above and determine the general digital camera imaging distortion parameters and the inner orientation elements of the camera. The setup of camera distortion chooses K, P coefficient method which is compatible with the Mathematical Distortion Model. The precision evaluation is also available in this paper. The results showed that the error of calibration algorithm of the unit up to0.26pixels in this paper.(3) Deeply analysis and research the close-range photogrammetric coordinate system, proposes the method how to establish the close range photogrammetry engineering independent coordinate system and works it live in practice. (4) Research the common theory of close-range photogrammetry technology—the forward and backward intersection model. The forward and backward intersection model has been applied to the engineering practice and achieved an ideal result. Through the project example to prove its accuracy can reach lmm.(5) Represent a new method that how to measure the tunnel crack with the close-range photogrammetry technology and validate that the new method could meet the specific precision and accuracy requirements of the tunnel deformation monitoring crack measurement in the field. Through the project example to prove its accuracy can reach lmm.(6) This paper developed the software system of the tunnel deformation monitoring base on non-metric digital camera, called CRP DMS.