In order to research the influence of coal-rock mass morphology of mining space on the flow law of gas,the laboratory physical model and numerical computation methods were adopted to simulate coal mining activities.Th...In order to research the influence of coal-rock mass morphology of mining space on the flow law of gas,the laboratory physical model and numerical computation methods were adopted to simulate coal mining activities.The simulation results indicate that,after coal seam mining,the loose rock accumulation body of free caving,ordered rock arrangement body of plate damage rich in longitudinal and transverse fractures and horizontal fissure body formed by rock mass deformation imbalance are formed from bottom to top in the mining space.For these three types of accumulation bodies,there are essential differences in the accumulation state,rock size and gas breakover characteristics.According to this,the coal-rock mass in the mining space is classified into gas turbulence channel area,gas transitional flow channel area and gas seepage channel area.In the turbulence channel area,the gas is distributed transversely and longitudinally and gas diffuses in the form of convection with Reynolds number R_e more than100;in the transitional flow channel area,one-way or two-way gas channels are crisscross and gas is of transitional flow regime with R,.between 10 and 100.In the seepage channel area,there are a few vertical gas channels with R,.less than 10.In this paper,the researches on the gas orientation method in different partitions were further carried out,gas orientation methods of low-level pipe burying,middle-level interception and high-level extraction were determined and an on-site industrial test was conducted,achieving the effective diversion of gas and verifying the reasonableness of gas channel partition.展开更多
The evolution of gas bearing channels in the roof,and their spatial distribution,was studied.A complete consideration of gas flow changes through the stress-strain changes in the roof near a working face is made.The t...The evolution of gas bearing channels in the roof,and their spatial distribution,was studied.A complete consideration of gas flow changes through the stress-strain changes in the roof near a working face is made.The theoretical abutment pressure distribution using displacement monitors and borehole visual recording instruments allow a theoretical analysis.Field test research determined the conditions for formation of macroscopic gas channels.These appear along the working face roof,normally distributed to it.These results show that the coal rock stratification becomes a macroscopic gas channel boundary if its deformation is less than the lower layer,or greater than the layer above it.At the same time the stability is greater than the distance from the roof for hanging dew conditions.The working face advances and the roof gas channels experience a cycle of development.Microscopic channels dominate the initial stage then macroscopic gas channels form,develop,and close.The evolution of the macroscopic channels depends on the ratio between the distances from the new compaction area in the goaf to the initial stress area in front of the working face.The amount of daily advance of the face also affects channel development.The experimental observations in one mining area showed that the main gas channels are located about 2 and 6.2 m above the lower surface of the roof and that they have an evolution period 7 to 11 days long.展开更多
基金Financial supports for this work,provided by the State Key Basic Research Program of China(No.2011CB201204)
文摘In order to research the influence of coal-rock mass morphology of mining space on the flow law of gas,the laboratory physical model and numerical computation methods were adopted to simulate coal mining activities.The simulation results indicate that,after coal seam mining,the loose rock accumulation body of free caving,ordered rock arrangement body of plate damage rich in longitudinal and transverse fractures and horizontal fissure body formed by rock mass deformation imbalance are formed from bottom to top in the mining space.For these three types of accumulation bodies,there are essential differences in the accumulation state,rock size and gas breakover characteristics.According to this,the coal-rock mass in the mining space is classified into gas turbulence channel area,gas transitional flow channel area and gas seepage channel area.In the turbulence channel area,the gas is distributed transversely and longitudinally and gas diffuses in the form of convection with Reynolds number R_e more than100;in the transitional flow channel area,one-way or two-way gas channels are crisscross and gas is of transitional flow regime with R,.between 10 and 100.In the seepage channel area,there are a few vertical gas channels with R,.less than 10.In this paper,the researches on the gas orientation method in different partitions were further carried out,gas orientation methods of low-level pipe burying,middle-level interception and high-level extraction were determined and an on-site industrial test was conducted,achieving the effective diversion of gas and verifying the reasonableness of gas channel partition.
基金provided by the State Key BasicResearch Program of China(No.2011CB201204)the National Natural Science Foundation of China(Nos.51204187 and 51234005)
文摘The evolution of gas bearing channels in the roof,and their spatial distribution,was studied.A complete consideration of gas flow changes through the stress-strain changes in the roof near a working face is made.The theoretical abutment pressure distribution using displacement monitors and borehole visual recording instruments allow a theoretical analysis.Field test research determined the conditions for formation of macroscopic gas channels.These appear along the working face roof,normally distributed to it.These results show that the coal rock stratification becomes a macroscopic gas channel boundary if its deformation is less than the lower layer,or greater than the layer above it.At the same time the stability is greater than the distance from the roof for hanging dew conditions.The working face advances and the roof gas channels experience a cycle of development.Microscopic channels dominate the initial stage then macroscopic gas channels form,develop,and close.The evolution of the macroscopic channels depends on the ratio between the distances from the new compaction area in the goaf to the initial stress area in front of the working face.The amount of daily advance of the face also affects channel development.The experimental observations in one mining area showed that the main gas channels are located about 2 and 6.2 m above the lower surface of the roof and that they have an evolution period 7 to 11 days long.
