Research On Rapid Building Technology Of Mined-out Area Closed Wall

Goaf gas leak accumulation,explosion and residual coal spontaneous combustion in goaf has been a serious threat to the safety of coal mine production and people’s life and property,closed wall constructed in mined-out area is one of the effective methods to prevent such accidents.Existing closed wall has many problems,such as it is easy to crack under pressure,the process is complex,the equipment is heavy and difficult to operate,and its construction speed is slow.To solve these problems,this paper proposes a kind of goaf closed wall quickly filling technology.In this paper,set Chengzhuang coal mine 4320 fully mechanized caving face of Shanxi Coal Group closed wall building as engineering background.First of all,through using theoretical analysis and numerical simulation method,Analysised stress distribution and deformation of contact roadway,result showed that:the best position is 3m~5m far away from the intersections of contact roadway and return airway,reasonable closed wall thickness is 2 m.Then,discussed the performance requirements of closed wall materials,to improve the performance of expansion and toughness,we did modification ratio experiments on high water filling materials,thus we obtained a new kind of closed wall materials,then discussed its major performance.Results showed: under conditions of water-cement ratio of 1.5,the material’s 2h uniaxial compressive strength reached to 4.45 MPa,28d strength reached to 7.9MPa,90 d strength reached to 9.54 MPa.When material’s expansion is 19.72% and the amount of compression is 7%,there sidual strength of the material can reach to 63%.Secondly,according to the characteristics of the underground closed wall filling,designed underground mobile filling system.The existing filling has many problems,for example,equipment structure is complex,using too many people,so we developed a new filling equipment,which set the quantitative cutting,stirring and pumping into one,simplified the filling system,reduced the manual labor.We designed the filling template.Finally,we designed closed wall filling process scheme based on high water filling,then we did field industrial experiments and effect observation at several place of 4320 face.Practice results showed that:the using of new materials、new equipment and new technology to build a closed wall is with rapid construction,less material consumption,good confined effect,and is with a real promotional value.