STUDY ON APPLICATION OF DIGITAL CLOSE RANGE PHOTOGRAMMETRY TO MODEL TEST OF TUNNEL IN JOINTED ROCK MASSES
数字照相量测在岩石隧道模型试验中的应用研究

The application of the close range photogrammetric technique to the model test of tunnel in intermittent jointed rock masses is presented. The developed software package Photoinfor is used to capture the deformation patterns and to analyze the deformation evolution quantitatively during loading on the model edges. Meanwhile,a simple but effective approach,image borehole method,which is based on the digital image correlation method,is proposed to recognize and measure the rock broken zone around tunnel accurately. In this approach,some groups of image borehole,which are some straight-line-like pixel points with one pixel interval on test image,arrange symmetrically around the tunnel center along the radial surrounding rocks and are analyzed by the software PhotoInfor. The broken rock zone can be determined accurately according to the position of pixel point with rapid displacement change along the image borehole. By the approach,a phenomenon of rock masses re-breaking in broken rock zone is also found. This may be helpful to study the mechanical behavior of rock masses inside the broken zone. The result shows that the photogrammetric technique is a powerful tool for deformation measurement in the geotechnical experiment not only for the granular materials,which is more widely studied at present,but also for the rock similarity simulation test.