Study And Research Of Digital Photogrammetry To Rock Mass Joint Distortion In The Underground Structures

With the development of the west exploitation in China, more and more hydraulic tunnel and underground structures are being build. The modern hydraulic tunnel, especially 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 behind the times. A non-contact digital close-range photogram metric method is presented in order to overcome the difficulties in the deformation measurement of large-scale tunnel and underground structures. So, studying and applying this new method is not only necessary to both theory and practice, but also offered a new way of the displacement testing in this area.In this paper, in order to solve the difficulties which we face in the practice, we place the focus on the method of the non-metric digital camera and requires no control points and put it into practice, of which offered a new a method in this area. Compared with those traditional methods to monitor displacement by convergence measurement devices or total station instruments, it has the advantages of saving time, providing large quantity of measurement information and operational safety. The tunnel country rock deformation observation and laid 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 the oriesand methods---the front-and-back alternating imagery method and the standardization imagery, as well as their styles of photograph and working conditions respectively. In the engineering practice, one of them can be chosen to suit the specific field case. Overlay photograph of the same target point which is located in a tunnel cross-section is done by two digital cameras at the same time, and then the 3Dcoordinates of the target point can be computed out according to the given coordinates of the control points.