Study On Roof Structure And Movement Law Of Fully Mechanized Mining Face With Large Mining Height In Licun Mining Area

The main problems in the study of mine pressure and strata control are the law of destruction and movement of overlying strata.With the continuous progress of the working face,the size and distribution of the mine pressure have been in the dynamic changing process.Because of the continuous movement of the surrounding rock,the hydraulic support and the surrounding rock of the rodeway are constantly under force,and the size,property and change law of the stress are inseparable with the movement of the overlying strata.With the increase of mining height,the law of destruction of surrounding rock of the stope has certain particularity.Therefore,it is of great significance to find out the movement and development law of overlying strata under the condition of large mining height for safe and efficient production of the working face.In this paper,based on the research of the 1301 coal mining face in Licun coal mine,based on the mechanical properties and thickness of the roof,the roof is divided into three types,the immediate roof,the similar main roof and the main roof.The similar main roof is a hard rock which is located between the top of the immediate roof and the main roof.In the process of backstoping,it will cause the pressure of small initial pressure and small period of the working face,and the roof will eventually fall into the goaf,and can not form the beam of the transfer force for a long time.Through the method of theoretical analysis,numerical simulation and field measurement,the paper studies the roof failure and movement law of the large mining and high stope in Licun coal mine.The main conclusions are as follows.(1)There are also primary caving and periodic caving in similar main roof.The first collapse is still a "voussoir beam" structure,but the cycle collapse may appear two types of collapse,"voussoir beam"structure and "cantilever beam" structure.Based on the "S-R" stability theory,the stability of the basic roof is analyzed,and the work is explained by the roof model containing the crack.On the inclined plane direction,the strata behavior appears to be segmented and migratory.(2)Using the UDEC numerical simulation software and the 3DEC numerical simulation software to simulate the working face,the roof movement rules in the recovery process are summarized as follows:the first fall distance of the main roof is 30m,the periodic caving distance is 8m,the cycle fall form is the "cantilever beam" structure,and the initial pressure step distance of the main roof is 80m,and the periodic pressure step distance is 20m.(3)Using the theoretical analysis method and the data measurement method to calculate the support resistance of the support in the large-height mining face,and the support resistance of the support is R H=5326.28kN by the theoretical analysis method.The resistance of the support is R H=5326.28kN through the data measured method.(4)Field measurement of the strata behavior law of the 1301 working face.The measured results show that there is a phenomenon of periodic pressure in the working face during the recovery period.During the observation period,the average caving interval of the main roof period is about 10m,and the average period of the main roof is about 23m,the maximum deformation of the surrounding rock of the transport CIS slots is 84mm,and the maximum value of the deformation amount of the surrounding rock in the return trough is 67mm.The supporting force is 5901.24 kN,and the maximum resistance at the end of the cycle is 10516.66 kN.