| With the rapid development of national economic, projects of hydraulic engineering and traffic engineering is flourishing, and so is the tunnel construction, which is always confined mainly by various kinds of geological disasters. In order to ensure the normal operation of tunnel construction, it plays a decisive role to do geological prediction in the process of tunnel information-based construction.Although more and more attention are paid to geological prediction ahead of working face during tunnel construction at home and broad, the prediction level is not high and the method is not mature. The key reason of this situation is that the information of most prediction method is from investigations before construction, or simply depends on geophysics explorer means and ignores the geological information disclosed during construction. How to predict geological situation ahead of working face using the geological information disclosed during construction, is the core of information construction. In this thesis, this thought is through out the whole research.Relying on Geological Prediction Ahead of Working Face during Tunnel Construction of Zhuyong Highway (Taizhou Part) in Zhejiang Province and National Natural Science Foundation of P. R. China (40272117), some research is carried on in this thesis. Baihe tunnel, a part of Zhuyong highway in Zhejiang province, locates in Xianju County, the physiognomy features of which are mid-low hill controlled by cathaysian and neocathaysian structural system. The dominant rock mass is weakly or slightly weathered tuff. Joints and cracks are well developed, mainly trending N.W and N.N.E, widely opened, weak cementation, with a result of collapse and water inrushing.In this thesis, it is introduced the standard of layer division and property structure of all layers in the 3D geological information database based on GeoDataBase. 3D geological information database of Baihe tunnel is built, which consists of graphics library including contour, drilling hole, stratum information, joints and cracks, and monitoring instruments position, etc. and property databases, such as database of joints and cracks, monitoring database. And geological information disclosed in the process of tunnel excavation is spatial informationized, which provides a database support to do data mining and geological prediction ahead of working face.Through a deep understanding of the 3D GIS model, the 3D modeling approach working for geological prediction ahead of working face during tunnel construction is developed. The way of building 3D tunnel model based on GIS, and conversion between geodetic coordinates and construction stake number are introduced as well as 3D model of Baihe tunnel is successfully built. Besides, the way to express and construct drill data is suggested, and then the 3D stratum model of Baihe tunnel is built based on the drill data and Kriging interpolation. Finally, 3D display of Baihe tunnel as well as simulation and analysis come to fulfillment, after the construction of 3D physical model and joints and cracks model.Based on the GIS platform, mining useful knowledge from the previous 3D GeoDataBase, sufficiently analyzing the engineering information and geological data disclosed during construction, the intellectualized prediction model of 3D information in advance of geological disaster during construction is built. The general technical route of the study is informationized construction that is forecasting the condition of undisclosed part and modified the original design in real time according to the information of disclosed part. Thus, it provides the basis to modify support scheme, excavation method and working sequence, is a technical support and protection to safe construction reducing geological disaster.Introduce data mining theory to the system of geological prediction in advance to do knowledge finding and data mining in 3D engineering geological database and predict in advance the disaster possibly existing ahead of tunnel working face in the view of time and space using the disclosed geological information. From the standpoint of space, draw information of dominant instruction surface after analyzing the joint data from excavation process using 3D net work numerical modeling technique for random discontinuities of rock mass and fuzzy clustering analysis; build decision information table of tunnel geo-disaster using rough set theory; do data mining and knowledge finding in 3D engineering geological database adopting the function of attribution reduction in rough set theory; judge the influence factors to rock mass stability as well as the weight coefficient computing; and predict the possible disaster and stability of rock mass applying artificial net work and extenics theory. From the standpoint of time, combining the BP net work and ARMA model, do trend abstract and prediction of the monitoring data of rock mass pressure in both aspects of trendy and random. 3D visual output of prediction result on the platform of GIS, which is powerful in query and spatial analysis, is convenient to query and analysis of result.The main algorithms adopted in this thesis are rough set theory, fuzzy clustering analysis, artificial neural network, and Extenics in data mining theory. Based on the Arc Objects 9.2—GIS component of COM, with the development platform of Visual Basic, the system of tunnel construction forecasts in advance is developed on the basis of GIS. The system comprises some modules such as the management of spatial database, the construction of 3D model, the simulation of 3D net, spatial overlay analysis, spatial query, geological forecast, etc. what the system can do are data inputting, inquiring and managing of drilling data, joints statistic data and monitoring data; 3D model building of drilling hole, stratum and tunnel; 3D net simulation of discontinuities based on GIS, as well as computing RQD, abstracting dominant surface; spatial analysis and inquiring characterized by click inquiry and location query by special property; geological prediction ahead of working face by both approach of ANN and extenics; 3D rock classification, and analyzing the influence basin of shuttered zone applying the 3D analysis of the buffer zone in GIS; and forecasting time series of monitoring data by both approaches of BP network and BP-ARMA.Adopting the way and the system mentioned in this thesis, geological prediction ahead of working face is pursued in typical part of Baihe tunnel, and some conclusions can be obtained as below:1. The main origins of collapse and water inrushing in Baihe tunnel are its considerable length, developed joints and cracks, widely opened structure surface and its weak cohesion.2. By the attribute reduction in rough set, to analyze the affect factor of the stability of rock mass in Baihe tunnel, the result suggests that RQD, the angel between the tunnel axes and the controlling structural plane, the type of structure plane, the length of structure plane, etc. influenced the stability by different level, especially the type of structure plane as well as the character of groundwater.3. Comparing the results of stability of rock mass predicting from extenics and BP network, it can be found that these two prediction results are similar and accordant actual situation, which indicate that nonlinear theory is effect in dealing with geological prediction ahead in tunnel construction4. Time series analysis of rock mass pressure using BP-ARMA model indicate that this model can be used to analysis and predict monitoring data of rock mass pressure. Trend term extracted by BP reflects the overall trend of rock mass pressure, and ARMA reflects the random induced by rock mass structure and excavation progress. Compared with BP prediction, this method has higher accuracy.5. The prediction result of rock mass stability indicate that geological prediction ahead in tunnel construction using geological information disclosed in excavation is scientific and feasible. The research method is innovative and has application and promotion value.
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