Study On 3D Geological Modeling Of Railway Tunnel System

While in the process of the actual tunnel excavation, the geological environment changes of the rock, the complexity geological construction of the rock will both have negative effects on the construction. Therefore, having a clear understanding of geological characteristics of underground rock, the formation, geological distribution and risk parameters of the tunnel excavation contributes a lot to safe and scientific tunnel digging. The traditional 2D geological project method and single project technology can not meet the rapid development of railway construction.Based on what mentioned above, the thesis focuses on virtual tunnel excavation and risk forewarning system, combining with tunnel geological disaster risk assessment and prediction system, with 3D geological modeling and visualization system of long railway tunnel project as the settings. Aiming at the questions of security, science and planning in tunnel excavation, this thesis puts forward using computer virtual technique to realize simulation of tunnel excavation and research of risk forewarning module. The inner geological changes of the rock and the risks that may exist in the tunnel excavation are showed. This brings forward scientific foundation to the real tunnel excavation.For railway tunnel modeling, the study puts forward a tunnel modeling algorithm. The basis thought of the algorithm creates geological tunnel model with the use of Model Clipping Algorithm, taking original geological data as the bases. After building of the tunnel model, Formation Block Connection Algorithm is put forward to create 3D tunnel model by connecting the block with same properties together. The geological construction of the tunnel rock is revealed by tunnel roam technology, as well as the showing of the risk forewarning.The thesis elaborates the research method and theory of Model Clipping Algorithm. For there are some deficiencies in Weiler-Atherton algorithm: spaces are wasted by adopting complicated tree structure, time is wasted by calling the algorithm to do some needless clipping, and some special points can not be handled correctly. This thesis puts forward a improved polygon clipping algorithm. The improved algorithm uses single-linked list to store polygon, uses pre-handling method that can eliminates the situation of one polygon contains the other or one parts from the other, avoids clipping errors that caused by different direction of the two polygons. The special points are handled in the improved clipping algorithm that reduces the space complexity and computational time complexity and improves the accuracy of the algorithm.This thesis discusses interactive graphics software technology, puts forward a three-dimensional geological scene tree modeling method, which uses body, surface, line and point to separate 3D geological model. The Building of geological scene tree modeling provides a great convenience to the virtual display and software development of 3D tunnel model.This thesis quotes information that provided by TSP, develops a display subsystem of the risk forewarning. The system can forecast the risk information that may be existed in front of tunnel construction, such as the source type of risk, location and scale and other related information. It shows the forwarning infomation with graphics, and sets up a set of flashing caution light, indicates different levels by different colors.Studying of this system is of great significance and necessity in the realization of people-oriented spirit of the scientific concept of development, the use of advanced technologies and methods to achieve the scientific management, scientific design and safe construction of the construction of railway projects. It is also of great significance and necessity in the railway tunnel construction in China to enter the world's advanced level.