| In recent years,China's fully mechanized mining face complete equipment technology and its efficient coal mining method have developed rapidly and reached the world's leading level.However,China's geological conditions are very complicated and the coal seams are unevenly distributed,and the coal resources in the shallow part are gradually depleted.Therefore,the development of coal resources continues to move deep into the earth.The mining of super-high mining in deep wells of kilometer has become the development trend of efficient mining at this stage.The harsh environment faced by deep mining will pose significant challenges to the safety of the scaffolding equipment and the roof of the work surface.In view of this,this paper uses the combination of theoretical modeling,numerical simulation and field experiment verification to study the mechanical characteristics and stability of the super-high-height hydraulic support and the coupling mechanical properties between the bracket and the surrounding rock,and then determine the fully mechanized mining face.The adaptive support strategy of the super-high-lift hydraulic support group is as follows:The super-high-lift hydraulic support has a large structure and a high center of gravity,and its motion and attitude characteristics are highly concerned by engineering.In this paper,the kinematics equation of super-high-lift hydraulic support is established by vector closed-loop principle.The kinematics model of super-high-height hydraulic support with two degrees of freedom is established.The efficiency and friction coefficient of super-high-height hydraulic support and the external load of shield beam are obtained.The influence law of the position,the inclination of the jack jack,the inclination angle of the horizontal jack and so on.The problem of stability of hydraulic support for super-high mining height in fully mechanized mining face is more and more prominent.According to the principle of force and moment balance,the three-dimensional stability mechanical evaluation model of super-high-lift hydraulic support is established.Based on this,the lateral stability and longitudinal stability of the super-high-lift hydraulic support are studied.The different instability modes of the hydraulic support are obtained.The influence of parameters such as friction coefficient,mining height and external beam load on the stability of super high mining hydraulic support.At the same time,the stability analysis of the column hydraulic cylinder is established,and the structural stability of the column jack is studied to obtain the critical load.In order to obtain the structural strength and bearing characteristics of the super-high-lift hydraulic support,Solidworks modeling software and Workbench software were used to establish a three-dimensional model of the super-high-lift hydraulic support.The strength analysis of the model was carried out to obtain the deformation and stress of the super-high-lift hydraulic support after loading.According to the strain distribution law,the influence law of the upper end load of the top beam on the deformation and stress-strain distribution of the bracket is further studied.The strength analysis model of the column is established.The deformation of the column at both ends,the load end face distance and the angle of the cylinder fold line are studied.And the influence law of strength;finally,the dynamic response model of the hydraulic support beam under impact is established,and the influence of roof pressure and friction coefficient on the response of hydraulic support is studied.Based on the plate-shell theory,the medium-thick plate is used to characterize the top surface of the working face.Considering the different boundary constraints of the top plate during the initial breaking and periodic breaking process,the stability model of the initial breaking and periodic breaking of the roof is established respectively.At the same time,the coal wall stability model considering roof pressure and support force is established,and the influence law of coal body's own parameters,guard parameters and roof pressure parameters on coal stability is discussed,and the coal body elastic parameters are revealed for coal body.The influence mechanism of stability is proposed.Considering the elastic effect of the coal body at the front end of the fully mechanized mining face and the mining roadway on both sides,the hydraulic support is regarded as the elastic foundation,and the coupled hydraulic model of the pre-hydraulic support group-surrounding rock is established.The penalty function method is used to connect the coal wall and the mining roadway to the roof.The constraint function is added to the model;the influence law of different parameters on the coupling group-surrounding rock coupling system is studied,and the coupling law between the bracket group and the surrounding rock roof is revealed,and the adaptive support of the super high mining hydraulic support group is obtained.In order to verify the accuracy and scientificity of the above-mentioned model and research content,the mechanical characteristics of the super-high mining hydraulic support group-surrounding rock coupling support were carried out at the 12401 working face of Shangwan Coal Mine in Shendong Company of Inner Mongolia.At the same time,the super high mining height was carried out.The verification experiment of the hydraulic support operation model verified the rationality and accuracy of the established model.The research results of this paper can provide theoretical basis for the effective maintenance and management of the super-high mining height fully mechanized mining face in the deep mine,and provide theoretical support for the super high mining hydraulic support structure design,strength check and intelligent control,thus ensuring the work.The foundation of safety is laid,with certain theoretical significance and engineering value. |
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