Research On Failure Mechanism Of Deep Roadway With Large Deformation And Pressure Relief Support Technology Of Slotting Chimerism

Under the influence of high ground stress,the surrounding rock of deep roadway often appears nonlinear large deformation failure,and the surrounding rock structure and mechanical performance continue to deteriorate.When the traditional method is used to strengthen the support,the high stress in the surrounding rock is easy to lead to the damage of the support structure,resulting in the failure of the support structure,laying a huge potential safety hazard for the normal use of the roadway.In this paper,Majialiang coal mine 4# coal seam belt haulage roadway as the engineering background,comprehensive use of field measurement,theoretical analysis,mechanical testing,numerical simulation,field application and other methods,to study the deep large deformation roadway surrounding rock failure mechanism and stability support and other issues,from the surrounding rock stress control point of view,put forward a new type of cutting chimeric pressure relief support technology,The application effect of field industrial test is good,which can effectively control the deformation of surrounding rock of roadway,and provides a new control method for large deformation of surrounding rock of deep roadway.The main conclusions are as follows:(1)The depth of the main roadway in the 4# coal belt transportation roadway in Majialiang coal mine is large,the surrounding rock deformation is obvious,and the original support is damaged seriously.According to the results of in-situ stress measurement,the roadway is in a high stress environment;The results of physical and mechanical parameters test of roadway coal and rock samples show that the physical and mechanical properties of surrounding rock are poor,and the strength and bearing capacity are low;The results of roof drilling show that the joint fissures of surrounding rock are developed,the integrity is poor and the stability is low.(2)In view of the failure reasons of surrounding rock of deep large deformation roadway,the comprehensive analysis shows that high stress is the fundamental cause of large deformation failure of surrounding rock of roadway;The physical and mechanical properties of surrounding rock are poor,the strength and bearing capacity are low,and the joints and fissures are relatively developed,which aggravate the deformation of surrounding rock;The original support scheme can not adapt to the deformation of surrounding rock,the support strength is low,and it is difficult to meet the support requirements,which is the direct reason for the deformation and failure of surrounding rock.The mechanical theory analysis shows that the deformation of surrounding rock increases with the increase of the original rock stress and the thickness of the broken area.The control of large deformation of surrounding rock in deep roadway can be considered from two aspects: reducing the stress state of surrounding rock,improving the stress environment of surrounding rock;Or increase the support strength,enhance the surrounding pressure of rock mass,improve the residual strength of rock mass,and reduce the crushing degree of shallow rock mass.(3)From the point of view of stress control of surrounding rock,a new type of slotting chimeric pressure relief support technology is proposed,and the support mechanism is expounded combined with the energy support conversion law.Based on the analysis of mechanics theory,the best formula of pressure relief in theory is given.After the mechanical test of different pressure relief materials,the appropriate pressure relief material is selected as the large aperture pressure relief material,and the hole arrangement of the large aperture pressure relief material is optimized.Through the mechanical test,the best hole arrangement is determined as the triangle arrangement.(4)Through FLAC3D numerical simulation,the influence of slotting embedded with different layers,rows and columns of pressure relief materials on surrounding rock deformation is analyzed.With the increase of layers,rows and columns of pressure relief materials,the deformation of surrounding rock first decreases and then increases.It is determined that the single block size of pressure relief material with large aperture is 200 mm×200 mm×400 mm,the best embedding amount in surrounding rock is 3layers,3 rows and 2 columns;At the same time,through the comparative analysis of the cutting groove chimeric pressure relief support scheme and the original support scheme,it is found that the cutting groove chimeric pressure relief support technology can effectively improve the distribution characteristics of surrounding rock stress field,displacement field and plastic zone by inserting pressure relief materials into the two sides of the roadway,which verifies the rationality of the cutting groove chimeric pressure relief support technology.(5)The field industrial test results show that compared with the original support scheme,the maximum roof subsidence is reduced from 993.3 mm to 262.7 mm,the maximum approach of two sides is reduced from 1066.3 mm to 348.2 mm,and the deformation of roof and two sides is reduced by 73.6% and 67.3% respectively.The roadway deformation is effectively controlled,and the roof separation is in a safe range,The bolt stress is reasonable,the I-steel metal support is basically intact,and the surrounding rock is in a stable state,which can meet the requirements of roadway pedestrian and transportation,and verify the feasibility of slotting chimeric pressure relief support scheme.