在节理岩石隧道的三轴相似模型试验研究中,应用数字照相变形量测技术,采用自行研发的岩土工程数字照相量测软件系统PhotoInfor,对隧道围岩的变形破坏模式和不同围压作用下的变形破裂演变过程进行试验观测和定性、定量分析;针对隧道围岩破裂带量测难点问题,提出一种基于图像相关分析的围岩破裂带的准确识别新方法--图像钻孔法,通过在试验图像上沿着隧道周边径向设置多组pixel测点(一组测点称之为一个图像钻孔,各组测点间距为1 pixel),利用PhotoInfor得到隧道围岩破裂带分布图,根据各组图像钻孔测点位移的突变位置,可对围岩破裂带的范围进行准确界定,同时发现,隧道围岩破裂带产生后破裂区内岩块再破裂的现象,这将有助于进一步深入分析岩体破坏后的力学行为.研究结果表明:数字照相量测不仅在砂土模型试验中应用效果良好,也是岩石相似模型试验中有效的变形量测手段,在岩土力学与岩土工程试验研究领域中可广泛进行推广应用.
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 Photolnfor. 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.