| Tunnel engineering is a covered and linear engineering. In most situations, it passes through complicated geological conditions. It’s difficult to find out geological problems in preliminary geological investigation. As a result, there exist many unknown risks and potential safety hazards in tunnel construction. In order to avoid the risks and losses of blind construction, the informational tunnel construction method should be applied to detect geological conditions before excavation, which means the frontage rock condition such as the existence of underground water, fracture zone and other situations will be investigated. Therefore, it’s imperative to apply advanced geological forecast on tunnel construction technology research to detect the geological situation in front of the tunnel face.This thesis took Dongsong Hydropower Station Diversion Tunnel Project in Xiangcheng County, Ganzi City, Sichuan Province as engineering background. The topic focused on geological prediction theoretical principles and application of technology, and numerical simulation research based on the forecast results. By applying advanced geological forecast technology in soft rock tunnel construction process, this thesis set up a Group Penetrating Radar and forecast system of geological sketch method to deal with common geological disasters of soft rock construction. Moreover, on the basis of the forecast results of soft rock tunnel deformation characteristics and support scheme optimization of numerical simulation analyses, this thesis optimized the supporting scheme and excavation method.Research results:In the practical application of advanced geological forecast technology, the thesis verified the accuracy of geological radar advanced geological forecast technology. Thus, the forecasting accuracy rate achieved80%. If weak broken belt or rich hose is found in tunnel advanced geological forecast report, large deformation of surrounding rock would happen easily. Based on the result of practical application in this project, FLAC3D numerical simulation research is applied to study deformation of soft rock, which leads to the further understanding of deformation rule and deformation characteristics, soft rock deformation obtained a general rule:The deeper the tunnel, the greater the deformation of surrounding rock; the greater the lateral pressure coefficient, the greater the deformation of surrounding rock; the higher the strength of surrounding rock, the smaller the deformation of surrounding rock. Through the numerical simulation analysis, in this project, the benching tunneling construction method rather than the whole section excavation method is more suitable. Steel supports in the tunnel bottom adoption curve closed more effectively than the linear control rock deformation. Through the numerical simulation analysis, when tunnel secondary lining was taken into stress analysis, especially on the condition that outside load was about10%, the project would be more economic and reasonable. |
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