| The stability of surrounding rock of coal roadway is the basic guarantee for safe and efficient production of coal mine,which puts forward higher and higher requirements for roadway quality.The 3-1 coal in Menkeqing Coal Mine is brittle,endogenous fissures and high in-situ stress,which makes strata behavior of 3108 main haulage roadway serious.As a result,the surrounding rock needs to be continuously expanded to form a rectangular section during the roadway driving,and then the displacement and deformation of the surrounding rock are increased and the shallow part is more loose and fragmented,which seriously affects quality and stability of the coal roadway.In coal roadway field,it is found that when the speed of roadway driving is accelerated,the strata behavior moderates,the side brushing is decreasing,and the surrounding rock structure is more complete and stable.In this regard,taking 3108 main driving roadway as the engineering prototype,the mechanical parameters of coal samples are determined through field investigation and physical experiment,the mechanism of the speed effect of strata behavior in coal roadway is analyzed by theoretical analysis,and the law of the speed effect of strata behavior in coal roadway is summarized by FLAC3 D numerical simulation,which is finally verified by engineering practice.The main conclusions are as follows:(1)The uniaxial compressive strength,tensile strength,elastic modulus,cohesion and internal friction angle of 3-1 coal are 16.67 MPa,0.66 MPa,3.89 GPa,2.32 MPa and 30.7 degrees respectively.(2)It is concluded that the increases of driving speed of coal roadway reduces the deformation of surrounding rock by analyzing the time effect of surrounding rock deformation of coal roadway.The driving model of vertical stress of coal roadway about axial is established,and the stress driving is determined to be the speed effect mechanism of strata behavior in coal roadway.That is,when the speed of driving is accelerated,the stress transfer is faster,which makes the stress on the shallow part of surrounding rock.When the coal roadway keeps a high driving speed,the shallow part of the surrounding rock of the coal roadway always bears less stress,and its deformation is smaller,that is to say,the strata behavior moderates.(3)With the increases of driving speed,the stress of surrounding rock of coal roadway shows the laws of driving.When the coal roadway is drived at a speed of 1000 m per month,the shallow part of surrounding rock of coal roadway always bears low stress,which is the fundamental reason for moderate of strata behavior in coal roadway.The displacement and deformation of surrounding rock of coal roadway show the law of speed effect.When the driving speed increases from 600 m per month to 1000 m per month,the maximum moderate ratio of displacement and deformation of coal roadway is 57%,The increases of driving speed has the greatest effect on the moderate of strata behavior of coal roadway sides.The instant strata behavior makes up 68% of the final strata behavior,which is the most important part of the law of speed effect of strata behavior in coal roadway.The above laws are the actual effects of increasing the driving speed.(4)The convergence of surrounding rock in coal roadway decreases with the increase of driving speed: When the driving speed increases from 600 m per month to 1000 m per month,the moderate ratio of roof subsidence is 30%,the moderate ratio of convergence of the coal roadway sides is 31%.(5)In the coal roadway field,the fissures of surrounding rock with high driving speed are fewer and smaller.The bolt support installed in the coal roadway at 1000 m per month rises faster,loses less,has greater stability value,and is more stable after supporting.The strata behavior of coal roadway at 600 m per month is the most serious,and the expansion of surrounding rock gradually decreases to 0 m with the increase of driving speed.The increase of driving speed is more beneficial to control surrounding rock of coal roadway. |
PDF Full Text Request