Investigation On Failure Characteristics And Control Technology Of Roadway Surrounding Rock In Thick Coal Seam With High Gas And Rich Water

Gas and water are important hidden dangers for safe and efficient excavation of underground roadways.Due to the large area damage around the roadway caused by mining,a large number of macro fractures are generated,which makes gas and water rush into the roadway and cause underground safety accidents.Secondly,water and gas lead to the weakening of the strength and integrity of the surrounding rock,resulting in large deformation of surrounding rock.In serious cases,large area of roof caving and other roadway damage phenomenon occur.Therefore,it is of great engineering significance to study the damage characteristics and control technology of roadway surrounding rock under the condition of high gas and rich water.Based on the engineering background of 2606 Transportation lane of Zhangcun Coal Mine,Shanxi Lu ’an Chemical Industry Group,this paper analyzed the failure characteristics of coal rock containing gas and water by field investigation,laboratory test,theoretical analysis,numerical simulation and field application,built a multi-physical coupling model of plastic failure of coal,and explored the control technology of surrounding rock of roadway containing high gas and water.The following conclusions are drawn:(1)The surrounding rock composition of 2606 haulage roadway in Zhangcun Coal Mine is mainly quartz,mica and kaolin,among which kaolin is highly absorbent and easy to soften when exposed to water,and mica is easy to change the internal structure of coal rock when exposed to water,which is the internal reason for the failure of surrounding rock.The mechanical parameters of coal rock decrease with the increase of water content,which is the external reason for the failure of surrounding rock.After the confining pressure is discharged,the coal sample is mainly fractured longitudewise,and the macro-crack runs through the whole coal sample,and the permeability increases rapidly,which is the main reason for water infiltration into the roadway.(2)Based on the Drucker-Prager criterion matching the Mohr-Coulomb criterion to determine the plastic deformation of the coal body after the excavation of the roadway,a coupled multi-physics field model of the plastic damaged coal was constructed.COMSOL Multiphysics was applied to simulate the deformation of surrounding rock under the gas and water seepage condition.Water seepage leads to the increase of deformation and plastic zone of roadway surrounding rock.The roof subsidence for 30 days increased by 80% compared with that for 1day,and the movement of the two sides increased by 29.4%.Compared with water,gas has less influence on the deformation of roadway surrounding rock,but the increase of permeability after roadway excavation will cause gas to rush into the working face quickly.(3)Aiming at the geological conditions of high gas and rich water,the surrounding rock control method combining gas control and support is proposed,and the simulation method of bolt-cable combined support of roadway with high gas and rich water based on COMSOL Multiphysics is proposed.Firstly,the evolution of gas content under different drilling arrangements of gas predrainage and excavating-drainage collaboration on roadway head was analyzed,and the reasonable layout parameters were determined.Then,the displacement evolution law of roadway surrounding rock under different schemes of high prestressed bolt and cable cooperative support is analyzed,and the optimal numerical scheme of high prestressed bolt and cable cooperative support in lane 2606 of Zhangcun Coal Mine is determined.(4)The surrounding rock control technology scheme of high gas rich water thick coal seam roadway is tested and monitored on site.During this period,the gas desorption indexes K1 and S meet the safety requirements.The subsidence of the roof is stable at 140 mm,and the proximity of the two sides is stable at 75 mm.After a certain period of supporting time,the force of anchor bolt and anchor cable is stable,and there is no fracture,so the supporting effect is ideal.The research results of the paper can provide reference for the control of the surrounding rock under similar working conditions.This paper has 53 figures,9 tables and 82 references.