Research On The Risk Assessment And Geological Prediction Method Of Tunnel Geological Hazards

In recent years, the transportation infrastructure developed rapidly in our country, andthe highway construction in full swing, but China has vast territory, there was largedifferences across geological and topographical conditions, the tunnel contained in somehighways have continued to increase, especially with the national implementation of thewestern development strategy in2000the highway mileage increased sharply in southwest,as well as the tunnel mileage. In the process of building the tunnel, there was often cannotaddress the disaster area all hide in geological conditions in the pre-survey and design phasewhich brings to the construction process risks due to the complexity of the geologicalconditions and the limite of technical conditions. In order to minimize the possibleemergence of geological disasters, to protect the safety of the tunnel construction process,this paper studied the geological disaster risk assessment and geological prediction methodin tunnel construction, the main research contents and results showed as follows:On the basis of comparison of various advanced prediction technology, this papermainly analyzed the basic working principle of the TSP tunnel advance geological forecastanalysis system.On this basis,it mainly discusses the elastic properties of the rock mass, thekinematics theory of seismic wave and elastic wave theory,the basic characteristics andattenuation law of the seismic wave propagating in different medium are described indetail,which embodies the superiority of the TSP analysis system in the tunnel advancegeological forecast analysis.The geological landform conditions and tunnel engineering survey of FuSong tunnelarea are analyzed and introduced, the analysis results show that most sections of FuSongtunnel are buried deep,the lithologies are upper Jurassic brecciated tuff,containing calcareoussilty mudstone and grey mudstone,at the same time,it contains the hard rock and softrock,and the tuffaceous sandstone is hard rock.There is F1fault getting through the body,andmost of the surrounding rocks are weak permeable rocks,which won’t appear a large number of water burst phenomenon,the inward and outward mountain slopes are basically stable.Theengineering geological conditions are relatively poor. The composition and working processof TSP analysis system are introduced in detail,which is used in YingSong high-speed andFuSong tunnel project,based on the concrete analysis of the natural conditions andgeological structures in construction areas,the sensor and its ancillary equipments arescientifically and reasonably laid in the test sites,and the testing data are collected andanalyzed in strict accordance with the standard steps,so as to determine the characteristics ofrock mass and the grade of surrounding rock.Test results show that,using the TSP system oftunnel geological advanced prediction is of high accuracy,longer forecast distance,shorterdata processing time,and less influence on construction. Using the system can provideimportant geological information for the tunnel construction,and play an important guidingrole for the safety and smooth progress of the tunnel construction.In the comparison of several kinds of commonly used tunnel geological disaster riskassessment methods at present,analytic hierarchy process is selected to evaluate the tunnelgeological disaster risk.According to the difference of surrounding rock grade along tunnelsections,it is divided into three risk assessment sections,according to the evaluation results,combined with the risk factor check list,it is known that the major risk event of Ⅲ levelsection of surrounding rock is landslide,so is for Ⅳ level section of surrounding rock,andthe major risk events of Ⅴ level section of surrounding rock are landslides and water inrush.Combined the important geological information from the TSP advance geologicalforecast method with the geological disaster risk assessment methods, can be more accurateand effective to determine the tunnel construction geological conditions and thecorresponding constraints in front of the possible risk events, more targeted for constructionpreparation work and the preventive measures for the safety of the tunnel constructionsmoothly play an important guiding role.