Adaptability Analysis Of Large Mining Height Hydraulic Support

As the supporting equipment for coal mining,the hydraulic support is the key equipment to realize the comprehensively mechanized and automated coal mining,which main function is supporting the roof of the stope,preventing the roof falling and maintaining the safe operating space.It can be known from above that the adaptability of hydraulic support is the key factor to decide whether the working surface can be produced safely and efficiently.Therefore,designing the hydraulic support with high performance and reliability is an important way to improve the mechanization degree of coal mining.In the large mining face,due to the large thickness of coal seam mining and the large overlying strata caused by the periodic breakage,the impact dynamic load of the working surface becomes more and more intense.Therefore,the adaptability analysis of the large hydraulic support is of practical guiding significance.In this paper,the 8.2 meters large mining height support was taken as the research object.Firstly,the structural adaptability of the large mining height support to the supporting working surface was analyzed.According to the working conditions,the overall structure design of the large mining height support is completed.Then the mechanical characteristics of the support were analyzed by establishing the support mechanics model.The change rule between the joint force of the top beam,the front and the rear link force,the pressure of the back end of the top beam,the pressure on the front end of the base,the actual supporting strength and the support height were compared.Secondly,a finite element model of large mining height support was built based on Workbench,and the strength adaptability of large mining height support to support surface was analyzed.In this paper,the strength of the support between internal and external loading modes were compared and analyzed for the first time,and the change rule of the stress and the displacement of the large mining height support under 11 kind of working conditions were obtained by analyzing the internal loading mode.The paper also focused on the external laoding mode,and obtained the stress difference of support by comparing and analyzing with the two laoding modes.Because fatigue failure is also one of the key factors of support failure,the analyse of fatigue life adaptability of large mining height support was carried out on the basis of strength adaptability analysis,and the area of the minimum fatigue life times of large mining height support was obtained.At the same time,in order to avoid resonance phenomenon between the large mining height support and the frequency of the mining surface,the modal analysis of the large mining support was carried out.The above analysis showed that:(1)The front force and the cutting force of the top beam,the joint force of the top beam,the pressure of the back end of the top beam and the strength of the support all increased with the rise of the support,while the pressure on the front end of the base gradually decreased,and the forces of the forward and backward connecting rods gradually increased with the rise of the support.(2)The torsional case was the worst condition,under which the base and top beam were loaded the maximum stess.Under the eccentric loading condition,the stress value of the front connecting rod reached the maximum value in all the test conditions,and the displacement decreased and then increased from the top to the bottom.(3)The contractive analysis showed that the stress values of shield beam,base,connection rod and jack had little difference between the internal and external loading modes,except the stress of top beam,which will lay a theoretical foundation for the external loading experiment of large mining height support in the future.(4)The fatigue life times of the hydraulic support were smalle in the torsional and eccentric conditions,and the smalle position of the life times was in the top beam and the base plate.Most of the positions of the stents had been tested for more than 40 thousand times and reached the requirement of high reliability.Based on the above analysis and field application results,the design of the large mining height support was reasonable and reliable,and can meet the needs of large mining height support face.The adaptability analysis method of large mining height supports proposed in this paper can provides a new direction for optimal design of scaffolds.