| The coalfield geological conditions in China are complex.The fault structure in the mine field is developed,and the communication aquifer causes serious water gushing and drenching in the process of the roadway excavation.Being in the drenching environment for a long time will significantly weaken the strength of roadway surrounding rock.In addition,the surrounding rock itself in the fault zone is seriously broken,which further increases the difficulty of roadway support in water filled fault structure.In this thesis,the theory and method of coalfield tectonics,hydrogeology,hydrochemistry,fluid-structure coupling simulation and so on are used to study the water control mechanism and unclear water inflow source in water filled fault structural area,and reveal water immersion weakening ability and internal meso mechanism of surrounding rock.Water softening of fluid-solid coupling model was developed,the fault zone seepage coupling mechanism of water stress and fracture-and its effect on the stability of the roadway was revealed,the corresponding control technology of surrounding rock was put forward.An intelligent system for real-time monitoring of surrounding rock stress and bolt support status was developed to realize the real-time monitoring of surrounding rock stress and bolt support effect in water filled fault structure area.The main innovative achievements and understandings are as follows:(1)A comprehensive identification method of water inflow source based on conventional hydrochemical ion characteristics,trace elements and isotopes is proposed,and the hydraulic connection and water source characteristics of each aquifer in Beixinyao mine are determined.In most areas of the mine field,the Ordovician limestone water has hydraulic connection with the groundwater of Taiyuan Formation and Shanxi formation,and the Ordovician limestone water has vertical overflow;There is hydraulic connection between Cenozoic and Shihezi Formation,and there is hydraulic connection between Shihezi and Cenozoic and Shanxi Formation and Taiyuan Formation in some areas,with little impact on the whole.On this basis,three identification charts are established: Piper and Durov identification charts of conventional hydrochemical components and deuterium tritium isotope identification charts,which provide reliable support for the rapid identification of water sources in each aquifer and play an important guiding role in the rapid identification of mine water sources.(2)The weakening characteristics of coal and rock samples under the influence of water content are obtained,and the weakening mechanism of water rock interaction is revealed.The compressive strength and tensile strength of coal and rock samples have a negative exponential relationship with water content.With the increase of water content,the plastic characteristics of coal and rock samples are enhanced,and the acoustic emission count and cumulative acoustic emission energy of coal and rock samples are gradually reduced.In addition,the acoustic emission count and cumulative acoustic emission energy curve reflect the phased law of internal damage evolution of coal and rock samples with different water content.After the coal sample is soaked in water,the original joint fracture of the coal sample opens and the strength is further weakened,making the damaged fracture expand along the original fracture,resulting in the corresponding strength reduction,and weaking the acoustic emission signal.(3)A quantitative analysis method of pore and mineral composition evolution of coal and rock samples is proposed,and the pore evolution mechanism before and after water immersion are revealed.The threshold range of mineral composition reconstructed by CT scanning was accurately determined by XRD;the threshold range of pore and fissure reconstructed by CT scanning was determined by NMR.The increase of pores of coal and rock samples before and after water immersion is mainly caused by the decrease of clay mineral composition.After the coal and rock samples are immersed in water,the connecting hole communicates with the external water samples.The clay minerals in and around the connecting hole begin to expand,soften and dissolve in water and begin to diffuse.In the process of diffusion,some clay minerals diffuse into the external water,resulting in the increase of porosity of coal and rock samples;The other part diffuses and adheres to the connecting hole,resulting in the reduction of large fracture aperture and more uniform overall pore size distribution of coal and rock samples.(4)A fluid solid coupling numerical simulation method considering water immersion weakening is developed.This method calculates the water content and permeability of rock mass based on the fracture aperture.Then the fluid solid coupling numerical simulation method are embedded into UDEC numerical simulation software by FISH language.The fluid solid coupling analysis of the stability of roadway surrounding rock under the condition of water immersion weakening can be realized.On this basis,through the tensile strength and UCS test results of coal and rock mass under different water content in the laboratory,the block and joint parameters in the model are inversed,and the parameter changes of coal and rock mass under water immersion weakening in the numerical model are accurately obtained.(5)The instability mechanism of roadway in water filled fault structure area is revealed,and the roadway support technology in water filled fault structure area is put forward.The damage development of roadway surrounding rock can be divided into four stages: mining failure stage,fault activation stage,fault seepage stage and water immersion damage stage.The shear damage in the water filled fault structure area plays a leading role in the failure process of roadway surrounding rock,and the amount of shear damage is 4.5 times that of tension damage.The relationship between roadway roof subsidence and surrounding rock damage and calculation time increases in logarithmic form.On the basis,the solutions of drainage fault penetrating roof aquifer +grouting reinforcement of original fault fracture + strengthening support are put forward.(6)An intelligent monitoring device for real-time monitoring of surrounding rock stress and bolt stress is developed.The developed intelligent stress monitoring device for surrounding rock realizes the three-dimensional stress-strain monitoring of the normal and vertical plane of roadway surrounding rock.The developed metal intelligent stress monitoring device can monitor the axial force,tensile stress and strain,bending moment and shear force under the condition of bolt support without damaging the bolt body,and then analyze the safety degree of bolt support.The developed intelligent bolt is used to monitor and analyze the three-dimensional stress variation characteristics and bolt bolting effect of surrounding rock in normal roadway area and water filled fracture roadway area of Beixinyao mine.The progressive damage of roadway surrounding rock in water filled fault structure area is predicted and warned in advance,which provides a basis for the stability and safety evaluation of roadway surrounding rock. |
PDF Full Text Request