Study On The Method And Application Of Surrounding Rock Dynamic Classification Of The Karst Tunnel

Surrounding rock classification is key research and concern problem in thesurvey,design and construction phase of underground projects.Based on plenty ofengineering practices and researches,the scholars in domestic and foreign have gotplentiful and substantial results on surrounding rock classification methods.But thelevel of surrounding rock is difficult to evaluate and the classification method is lackin the tunnels of karst region.Based on taking the karst tunnels of Xuda Railway astypical examples and the basic ideas of BQ method,the paper established the modelof karst surrounding rock and stated how the dynamic classification is achievedthrough the analysis to the effect of commonly surrounding rock classificationmethods in field. The main research results are as fllows:（1）Based on the comparative analysis to the commonly qualitative andquantitative classification methods, and the evaluation on the application effect of Qsystem and BQ system in karst surrounding rock classification.The paper pointed outthe universal contradictions that the classification results in karst tunnels withcommonly methods are different to the actual situation.（2）Based on the research results about karst tunnels and BQ system,the paperput forward the index system and classification method of karst surrounding rock,andbring in the concept of coefficient of karst influence K3.（3）The proportion of index which affect coefficient K3was given by analytichierarchy process.The article qualitatively analysis the position,scale,distance ofhidden karst cave through numerical simulation and summarized the quantitativescoresheets of the7influence index combined with the other research results.（4）The author established the flow chart that how karst surrounding rock dynamic classification is achieved and explained how the level forecast of karstsurrounding rock was carried with geological advanced prediction methods such asgeological sketch,TSP,GPR and advanced drilling.（5）The research results about karst surrounding rock dynamic classificationabove was applied to the surrounding rock classification process of XianRendongtunnel and the results reveal that the method had higher accuracy and operability.