Study On Stability And Adaptability Of Four-Leg Support In Large Mining Height Down-Dip Mining Face With Deep Soft Rock

The stability and adaptability of hydraulic support vary with geological conditions,and it is not completely homogeneity and universality.This thesis is based on the "13th Five-Year plan" National Key R&D Program of China " Surrounding rock control and intelligent mining technology of 1000 meters deep coal mine ",with its demonstration mine,that is,the occurrence conditions of large mining height down-dip mining face with deep soft rock of Kouzidong coal mine,which belongs to china coal Xinji energy in Huainan mining area,as project background.By means of theoretical analysis,laboratory experiments,numerical simulation and field measurement,this thesis focuses on the instability form and mechanism of the four-leg support with large mining height,and the formation mechanism and control strategy of the non-ideal posture,as well as the roof load distribution characteristics and the adaptability of the support,and then the application of ZZ18000/33/72 D four-leg support with large mining height is studied,and the innovative research results are as follows:(1)Based on the analysis of the interaction characteristics between support and surrounding rock,the stability of the support can be divided into four types: no-load static and dynamic,load-bearing static and dynamic.The mechanical model of "supportadvancing mechanism" no-load and loading stability and mechanical model of mechanism stability of four-leg support in large mining height down-dip mining face are established,the bearing characteristic curve and kinematic relationship of the support are modified,and the no-load and loading instability mechanism of four-leg support in large mining height down-dip mining face is revealed,which provides theoretical guidance for the stability and adaptability design of support in strike-dip working face.(2)The analytical formula of critical load of four-leg support in large mining height down-dip mining face is derived,and the design method of differential rated working resistance of the front and rear legs of the four-leg support is put forward.The coverage index of the corresponding critical load on the canopy when the action point of the base resultant force is located at the front toe of the base,and the controlling index of the support to the stability of the end face were proposed,and the adaptability and optimization design principle of hydraulic support based on double quantitative evaluation index are established.(3)The kinematic relationship of one-to-one mapping between the position and attitude of the support and the driving ram is deduced,the necessary conditions for the canopy of the four-leg support to move in the desired posture and the posture change characteristics of the canopy and base during the setting load pressurization process were obtained.A cooperative double closed-loop adaptive control method for the canopy posture of four-leg support is proposed,simulation results show that this method can approach the target value with a good posture of the canopy;The joint adjustment strategy of ram in non-ideal posture of base under the condition of soft floor is put forward,which can provide guidance for field operation.(4)Based on the adaptability analysis of the support type and advancing mechanism type to the large mining height down-dip mining face with deep soft rock of Kouzidong coal mine,it is found that the no-load stability of the developed 7.2m high mining height four-leg support is not lower than that of the two-leg support of similar model,as well as the overall dimension and quality of the support,bearing stability,formation of non-ideal posture,adaptability between the critical load curve and the roof load distribution characteristics of the scene,and the controllability of the end-face stability and the specific pressure of the base are obviously better than those of the two-leg support;The reversed-mounted hinged relay bar is more suitable for the mining conditions of the mine,and the practice shows that it plays a good role in helping to clean the floor coal.(5)The support condition monitoring system is developed based on Lo Ra.It is found from the observation of support posture and mine pressure that the canopy is probably connected with the roof in the depression posture in the setting support,and the "lowering-moving-lifting" process of the support is stable and controllable,without sliding,toppling,mechanism instability and base into the floor during the period;The compressive strength of the roof is small,the overall distribution frequency of the roof load along the length of the canopy is in the shape of chinese characters "several",and about 85% of the load is located in the compression area of the front leg and the rear leg;The roof and coal wall are well controlled,and the working resistance of the whole 18000 k N and the rated working resistance of the front and rear legs shall be distributed in the proportion of 6:4 to meet the support requirements of the working face,and the protection height of 3.6 m face guard meets the protection requirements.In this thesis,according to the geological conditions of large mining height downdip mining face with deep soft rock of Kouzidong coal mine,a new model,improved technology and regulation strategy to improve the stability and adaptability of support are put forward.The test application shows that the stability and adaptability of ZZ18000/33/72 D four-leg support with large mining height are significantly improved,the surrounding rock control effect is good.It can provide theoretical guidance and practical experience for the mining of coal seams with similar occurrence conditions.