Improvement Of Surrounding Rock Classification Method For Large Section Cavern And Applied

The demand of energy is increasing year by year in China's economic development and the dependence of energy import is increasing year by year.Underground energy storage has gradually become the main way of foreign energy storage.Underground energy storage is mainly composed of large section caverns,whose stability directly determines the safety of energy storage.In order to ensure the stability of surrounding rock during the construction of underground energy storage,this paper analyzes the advantages and disadvantages of Q-value method and BQ-value method respectively in the field surrounding rock classification method based on a large section cavern project and realizes the automatic identification of joint parameters and the calculation of quantitative index of large section cavern.The results of this paper are as follows:(1)Through the research and analysis of the joint index acquisition process of Q-value method and BQ-value method as well as the determination results of the surrounding rock level,it is found that Q-value method has the advantages of simple joint parameter acquisition and more coverage levels than BQ-value method,that is more detailed description of the surrounding rock joint,but Q-value method also has too much interference of human factors in the process of joint parameter acquisition,resulting in the determination results larger than the actual rock level.The BQ-value method has the advantages of combining qualitative and quantitative methods,and the results are more accurate,but it also has the disadvantages of the complex process of joint index acquisition and the inconsistency of some qualitative and quantitative results;(2)This paper sums up and applies the on-site advanced geological prediction television imaging technology to the joint image acquisition,and successfully transforms the joint image from manual acquisition to mechanical acquisition;Introducing the image processing technology to the joint characterization parameter acquisition process,summarizes the specific algorithm applicable to the joint image processing according to the characteristics of the joint image,and clarifies the corresponding processing flow a complete and effective automatic joint image processing method and joint characterization information extraction algorithm are proposed.(3)Baseing on the K0+990 mileage face in the field,the joint data processed by the above algorithm is compared with the joint data in the field,and it is found that there are some errors in the calculation results of the algorithm,but within the allowable scope of the project,the applicability of the algorithm is verified;By applying the algorithm to the acquisition of nJ index in the Q-value method andvK index in the BQ-value method,the algorithm can be effectively reduced The interference of a large number of human factors on the acquisition of nJ joint group number in the Q-value method simplifies the cumbersome process of vK acquisition in the BQ-value method.The nJ index in the optimized Q-value method and the vK index in the BQ-value method are successfully reapplied to the six groups of face on site and the surrounding rock level calculation is carried out respectively.The results show that the optimized Q-value method can effectively modify the surrounding rock determination results,and this set of joint image acquisition method and the image processing algorithm has applicability in the process of surrounding rock classification.(4)Basing on the numerical simulation calculation of different spans of the large section cavern,the change rule of displacement,maximum principal stress and shear strain increment of the same grade of surrounding rock under different spans is obtained,which verifies that the span has an important influence on the stability of surrounding rock.Considering the above spans,the grouping of physical and mechanical parameters of surrounding rock at all levels in the large section cavern is completed,and each combination is not based on the strength reduction method,the limit of safety factor of surrounding rock at all levels is obtained from three angles of displacement,maximum principal stress and shear strain increment,the mathematical relationship between span and Q-value is established.By means of mathematical fitting,the mathematical relationship between span and Q-value is established,and the calculation formula of Q-value of basic quality index of rock mass is supplemented;(5)With the help of the mathematical relationship between Q-value and span and a large number of face data,the quantitative index of Q-value method is properly adjusted,and the safety factor is introduced into the determination of Q-value method,which improves the basic quality standard of surrounding rock mass of large section cavern;The rock mass corresponding to all levels of surrounding rock mass of large section cavern is obtained by the quantitative index of safety factor reflecting the stability of surrounding rock and the back calculation method physical and mechanical parameters;Based on the idea of rock mass quality index and engineering span surrounding rock classification,combined with the characteristics of large section cavern,the sub classification of tunnel structure and tunnel structure is given and its basic quality index is quantified;Through the limitation of upper limit of hard rock in BQ-value method and the idea of span reflecting classification,the quantitative index in BQ-value method is improved,and based on this quantitative index,the legal description of BQ-value is improved and modified;The improved Q-value method and BQ-value method are used to re determine the surrounding rock level of the above six groups of faces: the improved Q-value method basically eliminates the interference of human factors on its joint index,and the judgment result is consistent with the safety system number and BQ-value method,and a small amount of BQ-value method and Q-value method are modified according to the quantitative index of safety coefficient the judgment result of the inconsistency of law level.