| As the main support equipment of fully mechanized mining face,the main task of hydraulic support is to support the roof and floor of working face steadily,to prevent the roof from collapsing abnormally,maintain the efficient production of coal mining and transportation equipment in the working face,and protect the lives and safety of underground workers.Different coal mining faces have different requirements on the working performance of hydraulic support according to coal rock properties,coal seam thickness and mining height.Generally speaking,hydraulic supports need to have stable support capacity,reliable bearing capacity,and good adaptability.In the ultra high mining working face,the mining height is too high,the roof control distance is too large,and the roof pressure is more intense.This has higher requirements and stricter tests for hydraulic support's mining height control,fast and stable support,safe and reliable bearing.Therefore,this paper takes an 8.2m high mining hydraulic support as the research object,and makes a related analysis and Discussion on the stability and load-bearing characteristics of the high mining hydraulic support.This paper is supported by the 13th five-year plan of national key research and development program called surrounding rock control and intelligent mining technology of one thousand meters deep coal mine.In order to analyze the stability of the hydraulic support for extra-large mining height,this paper studied the instability mechanism of the support,found out four common instability conditions of the support,established the critical instability mathematical models of each condition according to the moment balance relationship,and obtained the theoretical solution of the critical instability angle of the support through theoretical calculation.Based on Pro/E,the three-dimensional model of the support is established,and the simulation model of the support instability is completed by ADAMS.The numerical solution of the critical instability angle of the support is obtained through simulation analysis.The theoretical solution and numerical solution are summarized and compared,and ultimately the ultimate instability angle of the hydraulic support for extra-large mining height under various working conditions is determined.In order to study the load-bearing state of the hydraulic support for extra-large mining height under different working heights,this paper equated the leg and balanced cylinder as springs,calculated the stiffness of hydraulic cylinders according to their working characteristics,established the theoretical load-bearing model of support,and obtained the theoretical solution of the force on the key hinge points of the support through MATLAB calculation.With the help of HYPERMESH and LS-dyna,the load-bearing simulation model of hydraulic support based on roof subsidence is established.Through the simulation calculation,the numerical solution of the force on the key hinge points of hydraulic support and the pressure distribution of roof and floor are obtained.In order to study the force transmission characteristics of the hydraulic support for extra-large mining height under impact load,this paper analyzed the support state of the hydraulic support at the working face,and summarized the way of the impact load acting on hydraulic support.The rigid-flexible coupling dynamic simulation model of hydraulic support is established by HYPERMESH and ADAMS.In the model,the leg and balanced cylinder are replaced by variable stiffness spring equivalently.According to the load-bearing mode of the support,the simulation of three working conditions of the top beam being impacted,the shield beam being impacted,the top beam being impacted and the shield beam being impacted at the same time are carried out respectively.The force on the hinge point of the hydraulic support under the impact load is obtained,and the sensitive impact area of the hydraulic support is summarized.It provides technical support for structural optimization of hydraulic support with large mining height and its application in working face. |
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