Study On The Method Of Dynamic Surrounding Rock Classification Based On Extension Theory

Based on a tunnel project in Kaiping Yangchun section of Zhongshan Yangchun expressway,this paper studies a dynamic surrounding rock determination method based on extension theory and puts forward a set of feasible solutions to the problems of geological mutation and inconsistency with the designed surrounding rock grade in the determination of surrounding rock grade of tunnel in engineering practice.First of all,due to the limitations of the previous geological survey and the existing surrounding rock classification methods,the traditional surrounding rock classification methods can not well cope with the current stage of tunnel excavation.For example,RQD method only considers a single factor;although RSR method,RMR method and national standard BQ method consider the influence of many factors,they only carry out qualitative analysis without quantitative analysis,and the traditional method does not fully consider the influence of construction on the stability of surrounding rock.In order to solve the construction problem of abrupt change of geological conditions in V-shaped Valley,this paper proposes a set of surrounding rock classification method based on the advantages of the traditional classification method and the theory of extension evaluation of surrounding rock.This method can fully consider the influence of construction on the stability of surrounding rock when rating.At the same time,with the further excavation of the tunnel,the monitoring data can be substituted into the method,so as to achieve The real-time correction of the surrounding rock grade can evaluate the surrounding rock grade in real-time,dynamic and closed-loop way.Applying the above rating method to engineering practice,comparing with the results of national standard BQ method,it is concluded that extension evaluation is feasible and accurate,and has objectivity,dynamic and wide applicability that BQ method does not have.At the same time,the accuracy of the above method is verified in the process of real-time correction of surrounding rock grade.In conclusion,the evaluation method of extension surrounding rock and the construction optimization scheme of V-shaped valley section proposed in this paper are of practical reference significance.