The Principle Of Gob-side Entry Retaining And The Stability Of Surrounding Rock In Deep Shaft Gangue Filling Working Face

At present,there are more and more deep coal mining in my country.How to recover deep coal resources safely,efficiently and environmentally is an important issue currently faced by my country’s coal industry and a key issue that must be resolved.It is an effective way to mine the deep coal resources scientifically by gob-side entry retaining after filling the gob with gangue in the fully-mechanized face of deep well.The basic principle is to use gangue filling to relieve the violent pressure of deep mining high-strength mining.Safe and efficient recovery of deep coal resources is achieved through scientific and reasonable methods of staying in lanes and surrounding rock control technology.However,the mechanical environment of the fully-mechanized face in deep wells is complex,and the movement law of overburden rock after the gangue filling in the mined-out area is unclear.The compressive mechanical properties and bearing capacity of the gangue need to be studied.A series of scientific and technical problems need to be solved,such as the control principle and technology of surrounding rock in the gob side entry of the face with gangue filling in deep well.In view of this,with the support of the National Natural Science Foundation of China(51804114),the paper based on the measured data of the 1302N-1 gangue filling face in the Xinjulong Coal Mine discusses the characteristics of the appearance of the ground pressure and the law of overburden movement in the deep well gangue filling face.Comprehensive theoretical analysis,numerical simulation,indoor tests and on-site monitoring,etc.,to study the principle of left-along roadway and surrounding rock stability control technology in deep well gangue filling working face,and to carry out engineering practice in Xinjulong coal mine 2305S-2# gangue filling working face.The main research work and conclusions are as follows:First,it is based on the measured data of hydraulic support working resistance of 1302N-1 gangue filling face in Xinjulong Coal Mine,advance bearing pressure of working face,fracture characteristics of stope surrounding rock and corresponding ground subsidence in filling mined-out area.And by using Udec numerical software,the laws of plastic zone,fracture field and movement of overburden rock in filling mining with caving mining and filling height of 0.6 times,0.8 times and 0.9 times are simulated.The results show that the pressure of the gangue filling in deep fully mechanized coal mining face is not severe.The cover rock in the goaf sinks in stages.The direct roof fall range is small.The basic roof breaks and the movement characteristics are not obvious.The surface settlement is small.When mining by caving method,the range of overburden cracks and plastic zone is large.With the increase of filling height,the range of overburden cracks and plastic zone is obviously reduced after gangue filling goaf.The overburden fracture and movement characteristics of the goaf gradually weaken,and the supporting pressure decreases accordingly.Secondly,the basic physical and mechanical parameters and impact tendency of xinjulong No.3 coal seam,roof and floor strata are tested.It is found that No.3 coal seam and its roof plate belong to the 2 types of coal rock layers with weak impact propensity.It is necessary to carry out anti-shock design.The confined gangue compression test shows that under the same compression displacement conditions,the smaller the gangue particle size,the faster the resistance increase,and the gangue after gradation increases resistance faster than the single particle size gangue.Within a certain particle size range,there is an optimal gradation that makes the gangue increase resistance the fastest.According to the actual measurement of deep well gangue filling working face,it has three typical compression characteristic curves of “step type”,“log type” and “S type” when the gangue filling goaf and direct roof collapse gangue are carried together.Thirdly,based on measured analysis,numerical simulation and rock mechanics test results,a bearing mechanical model of inverted trapezoidal overburden rock along the empty remaining roadway in deep coal gangue filling working face is constructed.Based on this model,the structural characteristics and deformation mechanism of surrounding rock along empty lanes in deep coal gangue filling working face are analyzed.And put forward the deep wells of “reinforce the roof of the roadway in advance and keep the roof intact”,“control the gangue wall bulge,column-wall cooperative bearing”,“prevent the impact of solid coal and control the destruction of coal gang” and “control the bottom drum to ensure the cross section of the roadway”.The basic principle of surrounding rock control along empty roadway in gangue filling working face.At the same time,the principle of supporting roadways along empty lanes in deep shaft gangue filling working face is put forward: that is,“fix the roof first,then protect the roof and then control the bottom”.Including the principle of “advance support,strong surface protection,deep anchoring” to keep the roof intact.Cooperative control of “reasonable width,lateral restraint,cooperative bearing” of roadside structure control.The protection principle of solid coal gang control of “stress relief,anti-shock,and chip control”.And the bottom plate control principle of “transferring high stress and ensuring cross section”.Eventually,a technology system for retaining roadways along the gob in deep well gangue filling working face is formed:(1)advanced strengthening technology of roof and solid coal gang;(2)pressure relief and erosion control technology of solid coal gangway in retaining roadway;(3)cooperative supporting technology of roadside supporting structure.Finally,combined with the actual situation of 2305S-2# working face,the gangue separation wall and the concrete-filled steel tube column are used for cooperative bearing,single+articulated top beam or single+π steel temporary support,and long-anchor cable deep reinforcement and roof lagging grouting reinforcement permanent support the control scheme of surrounding rock in the alleyway is monitored.And the application effect of gangue filling along the remaining alleyway is monitored.The results show that the wall and solid side displacement of the roadway along the gob in the 2305s-2# working face are not large.The roof integrity is good and the subsidence is small.The floor heave is large,and some sections of the floor are hardened and cracked.On the whole,the deformation of the surrounding rock in the left lane is within the controllable range,and the gangue filling working face has achieved remarkable results along the empty left lane.