Study And Application Of Digital Photogrammetry To Displacement Information Of Tunnel

With the development of modern tunnel,especially the long tunnels, the technical requirements of rapid long-span and safe construction are becoming higher and higher. The traditional wall-rock deformation measurement methods have been already unsuitable. So, studying and applying new method of non-contact measurement is very important to both theory and practice.In this paper, the focus is placed on digital photogrammetry technology which is applied to tunnel country rock deformation observation and layed a new approach to non-contact measurement. Digital photogrammetry technology obtains pictures of cross-sections by a digital camera,then the images are put into the computer and all the works of data calculating and analyzing are completed . Finally.the displacement information of the tunnel wall-rock deformation is achieved to provide necessary information feedback to the tunnel design and construction in time.This paper presents two kinds of wall-rock deformation measurement theories and methods-the front-and-back alternating imagery method and the standardization imagery, as well as their styles of photograph and working conditions respecttively. In the engineering practice, one of them can be chosen to suit the specific field case. The measurement principles of the two methods are both based on object point central point of lens and special co-linear equation of image point. Overlay photograph of the same target point which is located in a tunnel crossrsection is done by two digital cameras at the same time, and then the 3D coordinates of the target point can be computed out according to the given coordinates of the control points.In all, the deformation information can be gotten through the comparison of two measured results.In order to test the feasibility of such methods, field experiments has been done and good effectiveness has been obtained.