Simulaional And Experimental Study On Development And Evolution Of An Anticlinal Structure Mining Overlying Strata Fracture Field

Formation because of tectonic movement or mining not only can lead to stress redistribution,destroy the integrity of the rock strata,will cause the rock formation in the anticline formation of cracks in construction and mining fissure extension and inter-permeation,further development in part for the harmful gas such as confined water and gas channel and storage space,in order to solve the coal mine water inrush and gas disaster prevention and control,the phenomenon of mining face of high stress and safety in the working face support,through under the condition of the anticline structure,Analysis of rock because of the anticline structure formation of crack and the distribution of working face roof and floor stress change in advance,the structure of the roof breakage and damage,etc.,through a combination of theory and methods of similar material simulation and software simulation analysis,a more detailed study of anticlinal structure formed in the process of the extension fracture and fracture distribution,as well as under the condition of the anticline structure development and spatial distribution of the mining-induced fractures and the fracture structure of overburden rock contact problem in time and space,the main research results are as follows:?1?In similar simulations:When the anticline structure continues to move,secondary fissures will be produced in the range of 20?25 cm from the anticline axis.In terms of the distribution of the fissures,the initial fissures are more developed and the fissures are more developed,while the secondary fissures in the anticline structure more,but the lower ones in the roof;From the micro level,it is found that the development of rock fracture extends from the bottom up,at the beginning The maximum width of fracture opening in the fracture zone is 1.8 cm;the two fracture zones are based on the central line of the axis of the anticline structure,and the nearly symmetrical distribution in the two wings of the anticline structure is generally"V"";in the process of formation of anticline structure,the fracture form in the initial fracture zone is roughly"?",while in the secondary fracture zone,the fracture form is mainly"?";?2?Under the condition of anticlinal structure,when the mining face is pushed along the coal seam,the influence of the secondary fracture zone in the anticlinal structure on the roof during the early stage of excavation is great,and the roof fracture and the development degree of the fracture are great.When the mining face is pushed into the initial fracture zone of anticline structure,the mining face support is seriously compressed and the fracture extension and connection degree is high,and the roof is prone to step subsidence.It is suggested that the mining face should strengthen the water exploration and drainage function when it passes through the initial fracture zone of anticline structure,and the working face should be inclined to pass through the initial fracture zone of anticline structure in advance;?3?In similar simulations Under the condition of anticlinal structure,when the mining face is pushed along the coal seam,the influence of the secondary fracture zone in the anticlinal structure on the roof during the early stage of excavation is great,and the roof fracture and the development degree of the fracture are great.When the mining face is pushed to the initial fracture zone of the anticline structure,the mining face support is seriously compressed and the fracture extension and connection degree is high,and the roof is prone to stair subsidence;?4?As for the development of stoping fractures,under the superposition of double stresses of geological movement and mining,stoping in the mining stage has a great influence on the development of fractures,and the fractures develop further.After the roof fracture is broken near the secondary fracture development zone of anticline structure,the lateral fractures begin to develop in the overlying rocks.When the mining is near the axial part of the anticline structure,the fracture development extends rapidly and the maximum height is 18 cm.The stoping fissure is developed laterally in the inclined mining stage.In the whole mining process,as the mining face advances,the roof appears to sink and break,the development and extension of the stope roof fracture shows a dynamic evolution process of"generation?the initial pressure of the roof?--development and extension?the bending and subsidence of the key layer?--closure?the periodic roof fall?;?5?Through FLAC^3D,the anticline structure under the condition of mining face advancing in roof and floor,through analyzing the stress distribution in the initial stages of coal seam mining,the mining face advancing to 15?30 m range,mining near the surface of coal wall stress concentration degree is bigger,coal strata pressure relief range near the start off to behind the mined-out area,and has also been gradually increases;When the mining face advances to the vicinity of the initial fracture zone of the anticline structure,the stress of the coal wall and the top and bottom of the goaf near the mining face changes greatly.In the normal advancing stage,the stress concentration of the coal wall in front of the mining surface gradually increases,while in the inclined advancing stage,the stress concentration in front of the mining surface first increases,and then gradually decreases with the roof breaking.