Study On Action Mechanism And Engineering Application Of Anchor Rod In Rectangular Roadway Of Coal Mine

With the increasing of mining scale and depth of roadway,the engineering geological conditions are becoming more and more complex,and the frequent accidents of roadway make the study of reasonable supporting parameters become the key to ensure the safety of roadway production.Because of the convenience of construction,rectangular roadway is widely used in coal mine development.By equivalent rectangular roadway to circular roadway,the traditional bolt support design method determines the supporting parameters and analyses the deformation of surrounding rock.However,the deformation law of surrounding rock based on circular roadway is different from that of rectangular roadway,which makes the stress characteristics of anchor rod different.Based on the analysis and summary of the existing theory of bolt support,the research status and existing problems of anchor mechanism,the structural model of rectangular roadway is established according to the deformation law of surrounding rock of rectangular roadway.The deformation expression of surrounding rock of rectangular roadway is obtained by elastic-plastic theory analysis,the force of bolt is analyzed.and the design method of bolt support is put forward.At the same time,the model of surrounding rock reinforcement is established,the mechanical characteristics of surrounding rock are analyzed,and the method of evaluating the stability of surrounding rock is put forward.Based on the S12001 of NING TIAO TA coal mine,a reasonable design scheme of bolt support is put forward,combined with numerical simulation and field monitoring to verify the rationality of the theory,and the stability of surrounding rock of roadway is evaluated.The main research results are as follows:(1)The deformation law of surrounding rock of rectangular roadway is analyzed,and the structure model of rectangular roadway is established.According to the plane strain problem,the stress of the structural model is analyzed,and the deformation expression of surrounding rock is obtained by elastic-plastic theory.By example and combined with FLAC3D numerical simulation software,the deformation law of roadway surrounding rock and the deformation amount of surrounding rock are obtained,and compared with the theoretical calculation results,so as to verify the rationality of the theory.It provides theoretical support for bolt support design considering roadway surrounding rock deformation.(2)Based on the coordinated deformation of anchor rod and surrounding rock,the stress models of full length bond anchor rod and local anchor rod are established,and the expressions of shear stress and axial stress in anchor section are obtained.The stress law of anchor section is analyzed and summarized,and the design method of roadway bolt support is put forward.Combined with an example,the supporting design of roadway and the main influencing factors of anchoring section are analyzed.(3)Considering the change of the mechanical state of the surrounding rock,the model of the surrounding rock reinforcement is established,the expression of the mechanical characteristics of the surrounding rock after reinforcement is obtained,and the influence of different bolt support parameters on the mechanical characteristics of the surrounding rock is analyzed.On the premise that the axial stress and shear stress of anchor rod do not exceed the allowable value of stress,the method of evaluating the stability of the surrounding rock is put forward based on the ratio of the ultimate load to the bearing load of the reinforced body as the condition to judge the stability of the surrounding rock.(4)Applying the research results to the support design of the roadway of NING TIAO TA coal mine S12001,by using the numerical simulation and field monitoring results,this paper compared the reinforcement effect of roadway under original support scheme and new support scheme,and also evaluate the roadway stability.The results show that under the premise of ensuring the stability of roadway,the bolt support design based on the deformation of surrounding rock can better play the role of bolt strengthening surrounding rock,improve the self-bearing capacity of surrounding rock,and save the amount of anchor rod.