Deformation Law And Deflection Study Of The Deep Shaft In Thick Soil And Thin Bedrock Strata Under The Influence Of Mining

In recent years,deep vertical shafts in thick soil and thin bedrock strata,represented by the Juye coalfield,have experienced new damage problems due to shaft deviation.This is distinct from the previous vertical compression failure of shafts,and its deviation mechanism is unclear,posing a huge hidden danger to the safety production of coal mines.The deformation and failure of the shaft are essentially the result of the interaction between the shaft structure and the surrounding strata,and coal seam mining is the main factor that changes the state of the strata.Therefore,in order to explore the deformation law of the deep vertical shaft in thick soil and thin bedrock strata and analyze its deviation mechanism,it is necessary to conduct in-depth research on the deformation law of the thick soil and thin bedrock strata and the shaft movement under mining.This thesis conducts relevant research using analytical analysis,numerical calculation,physical simulation experiments,and on-site measurement analysis methods.Firstly,a dynamic prediction model for deformation and movement of thick soil and thin bedrock strata and shaft was established,and its analytical solution was obtained.Considering the particularity of thick soil and thin bedrock strata,the probability integration method cannot accurately describe the movement and deformation changes of the soil rock double layer medium strata.Therefore,based on the combination of probability integration method and the Knohe time function,the vertical displacement on the surface of the bedrock layer caused by coal seam mining is regarded as the change in soil settlement caused by mining thickness,Furthermore,a dynamic prediction model can be established to describe the changes in thick soil and thin bedrock strata,as well as deep vertical shaft changes.By analyzing the variation of shaft displacement with geological parameters,mining parameters,and predicted subsidence parameters,the deformation law of deep vertical wells in thick soil and thin bedrock strata under mining conditions was obtained;The reliability of the model is verified by the surface subsidence monitoring data and the auxiliary shaft Deformation monitoring monitoring data validation of Zhaolou Coal Mine in Juye Coal Field.The results indicate that the dynamic prediction model proposed in this thesis can better calculate the deformation of strata and shaft caused by mining in thick soil and thin bedrock formations.Secondly,a three-dimensional numerical calculation model for mining thick soil and thin bedrock was established,and the displacement solutions of strata and shafts under different mining forms were solved using this model.The influence of coal seam mining on the movement and deformation of strata and deep shaft shafts was studied,and the influence of different mining factors on shaft deformation was revealed.On this basis,the possibility of symmetrical mining to reduce the risk of shaft deviation in thick soil and thin bedrock strata was studied.The results indicate that compared to symmetrical mining,unilateral mining of coal seams does indeed result in more significant horizontal displacement of the shaft,providing a research basis for symmetrical mining methods to reduce shaft deviation in thick soil and thin bedrock strata.Thirdly,a three-dimensional similarity simulation test model for the deformation of thick soil and thin bedrock surface and shaft under mining with large similarity ratio has been established.Based on the experimental principle,a similarity test system has been developed.Based on the similarity theory,a physical simulation model for mining deformation of deep vertical shafts in thick soil with a similarity ratio of 1:1000 was established for the first time using a seepage hydraulic simulation gravity field and the "kilometer surface soil freezing method drilling simulation test system".The impact of mining on surface vertical deformation and the influence of different mining methods on shaft deflection deformation were studied.The results show that coal mining will cause horizontal movement of the shaft towards the mining direction of the working face,with the maximum horizontal displacement value at the shafthead;As the mining thickness increases,the horizontal displacement value of the shaft caused by mining increases,and shows an approximate linear relationship.Comparing the horizontal displacement values of the shaft caused by three mining methods,it was found that the order of influence of different methods on the horizontal displacement of the shaft is: unilateral mining>symmetrical sequential mining>symmetrical simultaneous mining.Finally,a comprehensive study of various research methods revealed the mechanism of shaft deviation in thick soil and thin bedrock strata,and provided methods to reduce the risk of shaft deviation.Based on the measured mining parameters of the working face,shaft deformation and strain data,the influence of mining on shaft deformation was verified.By comparing and analyzing the theoretical analysis,numerical simulation,and physical simulation test results,the boundary angles of the three calculation models were calculated,and then the size of the protective coal pillar under the current standard was calculated,which is in line with the actual range of protective coal pillar size.The rationality of the three model calculation methods for displacement calculation in thick soil and thin bedrock strata was verified.Comparing three mining methods,it is concluded that asymmetric mining is the main cause of shaft deviation.The shaft within the influence range of mining is disturbed by rock and soil,resulting in deformation towards the working face direction.However,symmetrical mining in the mining area can also cause shaft deviation.Compared to asymmetric mining,symmetrical mining brings smaller shaft deviation,And the shaft deviation caused by symmetrical sequential mining in the mining area is greater than that caused by symmetrical simultaneous mining in the mining area.Based on the actual situation,suggestions for the prevention and control of shaft deviation in thick soil and thin bedrock strata are provided regarding the layout of mining areas,providing new ideas for the prevention and control of deep shaft deviation in thick soil and thin bedrock strata.In this thesis,there are 102 figures,22 tables and 171 references.