Research On The Response And Internal Correlation Of Bolt Support With Different Rock Mass Grades

During the exploitation of underground resources,the stability of rock roadway directly determines whether the mine engineering can be carried out safely.Certain support methods can effectively improve the stress state of rock mass and alleviate stress concentration.Bolt support which is the way of active support is the most important support method.Therefore,it is of great engineering significance to study the influence of bolt support on the stability of different rock mass during excavation.Based on an iron ore in East China,this paper uses FLAC3 D numerical simulation software,combined with numerical analysis and theoretical analysis,to study the minimum safety factor of surrounding rock and support structure under different rock mass classes and support parameters during rock tunnel excavation.The following research results have been achieved.(1)Based on a variety of surrounding rock classification theories,bolt support mechanism and previous research results,the values of bolt support parameters and rock mass parameters were studied.At the same time,when the load of the surrounding rock is greater than the ultimate bearing capacity of the rock mass,the surrounding rock is very likely to be damaged.(2)The orthogonal experiment method is used to simulate the excavation and support of the rock roadway,and 7 kinds of support schemes,20 kinds of surrounding rock grades,and a total of 140 kinds of simulation schemes are adopted.To obtain the corresponding curves and stability evaluation criteria by analyzing mechanical characteristics such as displacement,stress distribution and plastic zone of surrounding rock.Obtaining the minimum safety factor by analyzing the force of the supporting structure(anchor rod,plain shotcrete),and then getting the empirical formula by data fitting.(3)According to the above results and relying on the project,analyze the secondary disturbance of the rock roadway excavation to the existing rock roadway in the upper part.The results show that the vault displacement of the rock roadway is reduced by 17.2%,the horizontal displacement is reduced by 19.11%,and the bottom settlement of the existing rock roadway is reduced by 17.9% after using the bolt with plain shotcrete support.