Study On Stability Control Of Surrounding Rock Of Large Section Roadway With Variable Inclination And Buried Depth

In recent years,with the continuous exploitation of coal resources in our country,the coal resources with shallow burial,good geological conditions and easy to exploit will be finished soon.Those coal resources with poor geological conditions will become the object of our mining,and the difficulty of mining is increasing.Controlling the stability of surrounding rock of roadway will be the basic guarantee for the safe and smooth exploitation of coal resources.Combining with the scientific research project of "Long Quan Coal Mine South Roadway Supporting Scheme Optimization",this paper makes a thorough study on the control of surrounding rock stability of roadway under complex geological conditions by means of theoretical analysis,numerical simulation and engineering measurement.The main conclusions are as follows:(1)The results of peeping the roof surrounding rock of the southern belt roadway show that the peeping depth of the southern belt roadway reaches 15 m,the roof is fragmented and the cracks are developed in the peeping depth range,especially in the range of 1-2m and 6-7m of the roof plate,accompanied by longitudinal cracks,and water gushing out from time to time,which has a significant impact on the stability of the surrounding rock of the southern belt roadway.Therefore,the anchorage quality of bolts and cables must be guaranteed,and the anchorage length of roof cables should be lengthened appropriately(from 1.55 m to 1.8m),so as to improve the quality of roadway anchorage and the overall stability of surrounding rock.(2)According to the characteristics of large variation of buried depth in South belt roadway(buried depth varies from 200 m to 600 m),the numerical analysis results show that when buried depth is 600 m,the roof and floor closure and convergence of both sides are three times as much as that when buried depth is 400 m,the stress of surrounding rock increases by 50% compared with that when buried depth is 400 m,and the plastic damage range of surrounding rock of roadway is obviously larger than that when buried depth is 200 m and 400 m.Therefore,when the buried depth of roadway section is less than 400 m,the original support scheme can basically meet the stability requirements of roadway surrounding rock;when the buried depth of roadway section is more than 400 m,the support intensity should be improved,and the monitoring and management of the constructed roadway should be strengthened,so as to ensure the safety of roadway.(3)According to the obvious change of inclination angle of South belt roadway,the research shows that with the increase of inclination angle of roadway,the weight of overlying strata generates component in inclined and vertical direction of inclined roadway,which leads to the increase of shear stress between strata and the decrease of vertical stress compared with horizontal roadway,and then causes the shear action between strata to be strengthened continuously,and the shear breakage of bolts and anchor cables occurs.The shear stress will offset part of the horizontal stress,and the bottom heave phenomenon will be weakened with the increase of inclination angle.When the inclination angle is 20 degrees,the roof subsidence increases by about 33.85% compared with the horizontal roadway,the floor heave decreases by 6.85% compared with the horizontal roadway,and the convergence of both sides increases by about 40% compared with the horizontal roadway,which is not conducive to normal safety production.It can be seen that the change of inclination angle of roadway has a certain influence on the stability of surrounding rock.Therefore,in practical engineering,it is suggested to increase the diameter and pre-tightening force of anchor bolts and cables to increase the shear resistance between rock layers.(4)Based on the analysis of the influencing factors and the stability of surrounding rock of the south belt roadway,the support parameters of the south belt roadway in Long Quan Coal Mine are optimized when the depth of the roadway is more than 400 m.The results of engineering application and monitoring show that when the buried depth is more than 400 m,the maximum deformation of the two sides of the roadway is 33 mm,the maximum subsidence of the roof is 45 mm,the maximum separation of the roof is 10 mm,the stress of the anchor cable is more reasonable,and the damage scope of the roadway is obviously reduced.It shows that the support effect of the optimized support scheme is good,the stability of the roadway is obviously improved,and the roadway surrounding is basically satisfied.Stability requirements of rock.