Research On Single-point Digital Photographic Method In Similar Material Model

Mining subsidence is the direct cause of geological disasters, effectively control and reduce the degree of ground subsidence is the important technical means to reduce or avoid environmental hazards of mining subsidence , in order to make full exploitation of underground mineral resources and minimize mining subsidence , make a correct prediction of mining subsidence situation and design the range of protective coal pillar before exploitation to guide the conduct of safe production.Professional measurement cameras are always the mainstream of equipment in the similar material model experiments of the traditional displacement,which has such disadvantages as complex operation and high cost, meanwhile, it greatly limits the application of the digital photogrammetry in exploitation.In recent years,with the development of CCD technology, high-resolution digital cameras have become more and more popular, it has clear images which can be directly processed by computer. Althought, the ordinary digital camera is not measured camera, it can not be directly applied in digital photogrammetry. The paper analyzes the theory of ordinary digital camera applied in digital photogrammetry and adopts the suitable displacement measurement method for the ordinary digital camera on the basic of the digital photogrammetry principle.According the limitations of the displacement observation of the similar material model and the system analyses of similar material model theory, digital camera method was used to the displacement observation of the similar material model for the first time. The control grid was placed independently around each measuring point and pictured by digital camera, and digital photos were processed by the conventional mapping software, then obtain image coordinates of control grid angle point and markers of measuring points. By choosing the suitable model coordinate transformation and the correction model of image distortion and lens to calculate the actual coordinates of each measuring point in the independent control grid. The research of similar material model in a cetain mining area of Tongchuan shows that, this method is simple and practical, determined high-precision and reliable in measuring displacement, so it has some value of popularization and application.