Study On Reasonable Coal Pillar Size And Support Mode Of Mining Roadway Excavating Along Gob In Nalinhe No.2 Mine

With the increase of coal mining depth,the mining stress state is more complex.Under the influence of"three heights and one disturbance",the problem that the mining roadway is generally difficult to support is increasingly prominent.At the same time,it increases the risk of rock burst.In this paper,the goaf roadway excavation at the 31120 working face of Nalinhe No.2 Mine was taken as the research object.Through theoretical analysis,numerical simulation and field measured data analysis,the failure mechanism of surrounding rock of the goaf roadway at the 31102 working face in the same plate with 31120 was analyzed,and the reasonable coal pillar size of the goaf roadway excavation at the 31120 working face was studied.The initial design scheme suitable for 31120 working face is put forward,which provides certain theoretical basis and reference for mine safety mining under similar conditions.Using WQCZ 56-type of surrounding rock strength test device and SYY-56type hydraulic fracturing in-situ stress measurement instrument of 31120 working face under the specific circumstances of geostress and rock strength test,provide the basis for study of theoretical analysis and numerical simulation on the back data to support.In order to better maintain the stability of gob-side roadway and design a reasonable support system,the stress and deformation characteristics of surrounding rock of gob-side roadway in Nalinhe No.2 Mine 31102 working face（which is the same as the research object 31120 working face in the 31st panel）are analyzed and studied,and the causes and mechanisms of deformation and failure are found out and summarized.It lays a theoretical foundation for the reasonable arrangement of gob-side roadway and the design of effective support system on 31120 working face.Based on the theory of arc triangle block structure and the limit equilibrium theory of surrounding rock,the reasonable size range of coal pillar for goaf roadway excavation at 31120 working face is calculated theoretically.The reasonable size range of coal pillar is determined to be 5.01～6.8m theoretically.Considering that slabs occur during roadway excavation and cracks are relatively developed at the side,in order to ensure the overall stability of coal pillar,the size of small coal pillar is taken as 6m.According to the results of the previous geomechanical tests and the parameters of 31120 working face,the FLAC^3D numerical model was established to simulate the goaf roadway excavation with different coal pillar sizes（3～10m coal pillar）in the period of heading and stoping.By co MParing and analyzing the stress and displacement changes of goaf roadway excavation with different coal pillar sizes in the period of heading and stoping,the stress and displacement changes of goaf roadway excavation were analyzed.The coal pillar size of 6m was selected to verify the theoretical analysis.In view of the strong rock burst risk characteristics of the roof of 31120 working face,the reasonable selection of bolt（cable）support material parameters was analyzed theoretically and simulated.On this basis,different bolt（cable）support schemes were simulated and co MPared to select the most suitable support mode for the roadway of 31120 working face.Based on the arrangement and monitoring of the mine pressure measuring station on the 31120 working face,the seismic events,the law of energy change,the deformation of the roadway and the stress of the anchor rod（cable）are analyzed.The field application shows that the coal pillar size of 31120 working face is reasonable,and the supporting method of roadway excavation along the goaf is suitable for the condition of rock burst.This thesis has 52 figures,15tables and 101 references.