Research Of Tunnel Face Geology Information System Based On Digital Image

Starting from studying tunnel face geological images, this paper analyzes and processes tunnel face geological images through digital image processing technology. Structural planes, such as rock mass bedding, joints and faults, are automatically or semi-automatically extracted. For those obvious structural planes, they are corresponded between neighboring faces so that the three-dimensional geological structure model of the tunnel having been excavated part is rebuilt according to three-dimensional modeling technology. From this model, the information of rock mass structures in front of current face is predicted. All this information is given to tunnel design and construction, so as to offer important technical support for realizing tunnel information design and construction.The main conclusions and achievements are as follows:1. By using digital imaging technology, face images are pre-processed, edge-detected and boundary-extracted. For a structural plane, if any of its' boundaries are not continuous, boundary polymerization, auto boundary linking algorithm are introduced to connect this discontinuous boundary lines. These boundaries can be regarded as those in geological sketch. Once much manual intervention is applied, the boundary graphs can form geological sketchs. This will improve geological sketch speed. Correspondingly, the situation that manual sketch results are very different because of different sketch operators is efficiently controlled.2. Considering that undetected and false boundaries are often exist when structural plane boundaries are extracted automatically, manual intelligent scissor which combines auto extracting image boundary with manual intervention is introduced to semi-extracts structural plane boundaries. This method dismisses boundary extraction errors. And it also reduces boundary extraction time, energy, and inaccurate positioning. These cases often exist if completely manual intervention is adopted.3. Rock masse characters in faces are statistically analyzed by using digital image processing technology. The natural characters of structural planes, such as structural plane length, joint length of unit area, average distance between structural planes, RQD, are acquired. According to these data, the conditions of surrounding rocks in tunnel faces are described. So the function that automatically analyzed and evaluated face surrounding rock conditions is realized.4. For the surrounding rocks that are adjacent to faces and not laid lining, these questions that need to be cared during image collections are analyzed. And how to produce geological launched maps is researched.5. By digital image processing technology, characteristic extraction is applied to lots of rock image samples, which are gained through closely shooting many kinds of rocks. According to BP neural network algorithm, image characters are trained so as to obtain parameter model. This model can be used to automatically classify the lithology of different tunnel faces.6. In accordance with actually measured attitude information of structural planes, how to correspond with structural planes between neighboring faces is discussed. In the light of OpenGL three-dimensional modeling technology and correlatively three-dimensional rebuilding algorithms, the tunnel three-dimensional geological structural model is rebuilt, which means that the visualization of tunnel geological structure is realized. So the geological condition of having being excavated part of tunnel is acquainted more directly.7. Based on the three-dimensional geological structural model, the unexcavated part in front of current face is predicted. From the predicted model, geological launched map, cross-cutting surface, longitudinal cutting face and virtual geological drilling are built. At the same time, with the special coordinate relation of structural planes in geodetic coordinate system, all structural planes'attitudes and the angle between strike and the direction of tunnel excavation are analyzed and computed. All the information is useful to extensively learn about and analyze tunnel geological conditions.8. According to the analysis of tunnel faces, "Tunnel Face Geology Information System(TFGIS) 2008" has been developed, which provides strong technical support for tunnel information design and construction.