Research And Application Of Foamed Concrete With High Volume Of Fly-ash In End Filling Technology

With the adoption of roadway driving technology with narrow coal pillar, the coal pillar along gob side is easily to crush which forms air leakage resulting into mine fire. This thesis focuses on the fire prevention requirement of 73beneath03 working face in Baodian mine, takes thought about the fly- ash waste disposal, and put forward the idea of end filling of foamed material with high volume of fly-ash. First, a brief analysis about foam stability and reaction mechanism of each component is given out, and then a series of different mixtures with varying fly-ash contents is conducted with a combination of single factor analysis and orthogonal analysis method. Meanwhile, gob filling and plugging effect is analyzed by theoretical analysis and numerical simulation. Finally, filling system and process is carefully designed to industrial test implement. The main conclusions are as follows:(1) The foam stability mechanism and chemical reaction between the components of fly-ash slurry are analyzed. It is found that foam stability can be improved by enhance the surface viscosity and improve the uniformity of foam particle which helps to choose the appropriate foaming process; and the fly-ash stimulation methods are concluded through analyze of chemical reaction.(2) The effects of different components of the foamed fly-ash material are analyzed through experiments. A series of foamed fly-ash material specimens with different ratio of ingredients were made with the guidance of single factor analysis and orthogonal test method to conduct compressive strength test, and the relationship between compressive strength, dry density and solid/liquid ratio, fly-ash component, foam content, W/C ratio and additives content are analyzed to obtain the comprehensive best chose; and the relationship between ther mal conductivity and dry density, foam content are analyzed by the measurement of different levels of density sample; The “anti-crisp” compressive properties of material are analyzed through the contrast of load-strain curves.(3) The formation environment and factors of spontaneous fire in goaf are analyzed, and the effect of permeability on the field flow in goaf is studied by numerical simulation. To simulate the end filling material permeability on flow field in goaf distribution effect, through the end filling with foamed fly-ash material, the air leakage of gob can be effectively reduced.(4) The "Preparation- Transport-Mixing" system and bag end- filling process of foamed fly-ash materials are designed. In order to solve the high W/C ratio problem of ground pulping station, concentrated slurry system is taken; and pipe –wind foaming machine is developed with laboratory confirming test with 0.5MPa foaming pressure; end- filling process with bags have been put forward with "flexible net surplus lateral deformation and to pull in limit axial deformation” control method...