Study On Deformation Failure Laws And Adaptability Of Bolt Supporting In Deep Roadway With Broken Roof

With the increasing depth of coal mining,the stress and geological environment in the surrounding rock become extremely complicated.Especially the tunnel in the geological structure area,the roof often shows the characteristics of breakage.It is difficult to ensure the stability of the surrounding rock by the traditional bolt supporting technology.Based on the comprehensive research methods of theoretical analysis,numerical simulation,laboratory test and field monitoring,I analyed the influence factors of surrounding rock stability in deep broken roof roadway,dicussed the characteristics of deep broken roof laneway and put forward the evaluation method of roadway roof breaking degree.After that,I studied the relationship between rock fragmentation and the effectiveness of bolting support through experiments,and carried out the field test of deep broken roof roadway stability control.The main research results are as follows:(1)Through theoretical analysis and numerical calculation,we stuided the influence factors and depth of surrounding rock stability in broken roof roadway,the strength of the roof rock layer,and the influence of the roof joint properties and other factors on the Fissure-Evolving laws of surrounding rock mass of roadway.The lower the strength of roof joints are,the greater the density of fracture development.The development of the roof fissure mainly depends on the mechanical parameters of the fracture itself.The strength of the roof stratum has a very significant influence on the expansion of the plastic zone.(2)By comparing and analyzing the feature image data of borehole structure surface,we put forward the evaluation method for the degree of roadway roof crushing,and the comprehensive width of fracture width on the borehole image of unit length is used as a comprehensive index to evaluate the degree of rock fragmentation.It is applied to the analysis of the roof breaking degree of the roadway.Then we found that the strength of the fracture development of the roof surface,the bolt support end and the structural surface at the junction between top coal and upper direct roof strata are low,and are easy to appear the phenomenon of fissures and layers.(3)Through the similar material experiment,we can found that the anchor effect can not be fully utilized in fractured rock masses,and the adaptability of bolt to fractured rock masses support is reduced.Under the condition of high fractured roadway surrounding rock,the supporting function of bolt can not be brought into full play,and other auxiliary supporting measures should be taken to form a joint and coordinated support form to effectively control the surrounding rock of the broken roof roadway.(4)For the shallow roof with high crushing degree,high strength anchor is used to reinforce the bearing structure.For the deep roadway roof with high crushing degree,the“long anchor cable+short anchor cable" is adopted to improve the overall bearing capacity of the broken surrounding rock.For the broken surrounding rock of the roadway surface,we adopted the strengthened support measures combined with metal frame and reinforced concrete beam.It not only improves the integrity and strength of surrounding rock,but also effectively controls the deformation and maintains the stability of surrounding rock structure.