The Research Of Comprehensive Geological Prediction Technology And Fuzzy-analytic Hierarchy Evaluation In Micangshan Tunnel

As the complexity and variability of the tunnel geological hazards,hazards of water inflow,collapse and rock burst happen frequently during tunnel construction,which are huge challenges for the tunnel construction.In order to achieve construction safety,to avoid disastrous incidents and improve the efficiency of excavation,it's quite essential to carry out geological forecast to detect the geological conditions,especially poor geological conditions ahead of the tunnel face before excavation.The geological prediction methods commonly used in engineering were studied In this paper.Firstly,a principle of comprehensive prediction was developed based on the local geological forecasting and relevant research and applied in the practice of geological forecast of Micangshan tunnel.Then the geological hazard risk and overall risk rating in tunnel construction were evaluated by Fuzzy-Analytic Hierarchy Evaluation.The main research contents and achievements are as follows.(1)The principle,composition,data acquisition and processing of geological prediction methods such as geological analysis,TSP,geological radar and TEM were studied in this paper.Also the application scope,advantages and disadvantages as well as their sensitivity to different types of poor geological conditions of various geophysical predication methods were analyzed.(2)The technology system for geological prediction that takes geological analysis as basis,combines various geophysical methods,adopts advance exploratory drilling to verify the results is developed based on the local geological forecasting and relevant research.According to this system,the geological predication is carried out to reveal the geological information.Therefore the quality,position and size of the poor geological as well as the geologic hazard caused by it can be predicted.(3)Then the geological hazard risk and overall risk rating in tunnel construction were evaluated by Fuzzy-Analytic Hierarchy Evaluation.Correspondingly,the assessment methods are from qualitative description by words to quantitative express by mathematical model.This could be more intuitive and meaningful for engineering application.(4)Finally,the system for geological prediction was applied to Micangshan tunnel.The geological hazard risk and overall risk rating in tunnel construction were evaluated by Fuzzy-Analytic Hierarchy Evaluation.There the risk levels of the water bursting,collapse,large deformation and rock burst as well as the overall risk of geological hazard grade were obtained.According to the assessment results,corresponding plan was made to ease the risks.The results showed that the method provided an accurate and rational method to predict the geological hazard and effectively guided the construction.