| Hydraulic support is the main support equipment of comprehensive mechanized coal face which plays an important role in supporting the roof,preventing the roof from falling and ensuring the safety of equipment and personnel on the working surface.With the development of full-mechanized mining technology,the support height of hydraulic support increases gradually,the working force increases accordingly and the impact dynamic load becomes more and more obvious,which cause the stress condition of hydraulic support and the bearing condition of working face bottom plate become worse.Therefore,it is of great significance to analyze the mechanical characteristics and the specific pressure of the floor of the hydraulic support with extra high mining height.The paper takes ZC21000/38/82D as the research object,gives the space mechanics analysis method of hydraulic support and built a spatial mechanical model of the hydraulic support.Based on the multi-body dynamics simulation software Adams and meshing software Hypermesh,a numerical simulation model of rigid support and rigid-flexible coupling of hydraulic support was built.Based on the rigid body simulation model of hydraulic support,the variation law of support load under different support heights and different roof pressures was analyzed.Based on the rigid-flexible coupling simulation model of the hydraulic support,the thesis analyzes the changing law of the mechanical response of hydraulic support under five typical working conditions,and discusses the influence on different roof horizontal forces on the bearing characteristics of the support.It is concluded that as the support height of the hydraulic support decreases,the stress on the hinge points of the top beam and shield beam,the hinge point of the front link and the hinge point of the rear link all increase.Secondly,for the bad floor supporting conditions of large mining height working face,the bearing mechanical model of the support floor was established based on the elastic foundation beam theory.Based on the display dynamics software LS-DYNA,a specific pressure analysis model including supports,flexible roofs and bottom plates was built.The distribution rules of the bottom plate specific pressure under five typical working conditions and five supporting heights were analyzed,and different working conditions and the effect of the support height on the specific pressure of the bottom plate is different.But the specific pressure of the bottom plate is the largest at the corresponding position of the base socket,and the specific pressure of the bottom plate of the rear end is small,or even 0.Then,the thesis analyzes the influence mechanism of different floor geological conditions and base structure on the specific pressure distribution characteristics of the floor height of the super-large mining height hydraulic support.In terms of geological conditions,the three rock bottom plates of siltstone,argillaceous sandstone and coal rock were taken as the research objects respectively.By numerically simulating the distribution characteristics of the bottom plate of the support under five typical working conditions,the three lithological bottom plate conditions were analyzed.The distribution law of the specific pressure of the bottom plate of the lower bracket.Different floor rock properties have a significant effect on the floor pressure distribution.The softer the floor is,the smaller the floor pressure and the more uniform the distribution is.In terms of the base structure,the three types of structural bases,one-piece column sockets,"ten-shaped" socket ribs,and longitudinal ribs added behind the base,were compared with the original base structure.And the effects of different structural bases on the bottom plate specific pressure were analyzed.It is concluded that the specific pressure distribution of the bottom plate is affected by the base structure.The integral column socket and the "ten"-shaped column socket rib plate help to increase the load transmission path and reduce the specific pressure of the bottom plate.Longitudinal ribs are added to the rear end of the base to increase the rigidity of the base,which also helps to reduce the specific pressure of the bottom plate.In terms of roof pressure,the magnitude of the periodical pressure generated by different burial depths or periodical pressure steps is different.Five different magnitudes of roof pressure are selected for loading,and it is found that as the pressure of the roof decreases,the specific pressure of the bottom plate decreases increase.Finally,based on the planar structure of the hydraulic support,the post angle and force monitoring method of the hydraulic support,the balance jack length and the top plate pressure as independent variables,and the bottom plate specific pressure analysis method are established.Hydraulic support monitoring software. |
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