Specimens of steel fiber reinforced concrete （SFRC） in volume ratios of 0%, 0.5%, 1% and 1.5% were prepared to study the supporting effect of SFRC at these diffterent volume ratios in a deep soft rock tunnel. Experi...Specimens of steel fiber reinforced concrete （SFRC） in volume ratios of 0%, 0.5%, 1% and 1.5% were prepared to study the supporting effect of SFRC at these diffterent volume ratios in a deep soft rock tunnel. Experiments with mechanical properties of compressive strength in cubic specimens, cleave strength in cylindrical specimens and four-point flexure strength of sheet metal specimens were carded out. The experimental results indicate that SFRC in a volume ratio of 1% is superior in ranking to other volume ratios in terms of technique and economics. By means of a numerical simulation, given the characteristics of soft rock deformation and damage at great depth, a new support substitution scheme of SFRC to replace plain concrete is proposed. The results of an industrial trial show that the support provided by SFRC can withstand large deformations of the surrounding rock. Good resuits have been obtained in a practical anplication.展开更多
The heat How generated from the infinite rock mass surrounding the underground tunnels is a major cause for the increasing cooling demands in deep mine tunnels.Insulation layers with lower thermal conductivities on tu...The heat How generated from the infinite rock mass surrounding the underground tunnels is a major cause for the increasing cooling demands in deep mine tunnels.Insulation layers with lower thermal conductivities on tunnel walls and roof ceilings are believed to supply a thermo-barrier for heat abatement.However,it is found that no systematic theoretical investigations were made to predict and confirm the effectiveness of underground thermal insulation.Specifically,investigations on the underground insulation problems involving heat flows through the semi-infinite hot rock mass and insulation layer were not sufficient.Thus,in this paper,the thermal characteristics,accompanied with heat flow through the semi-infinite rock mass and the insulation layer,were modeled by both analytical and numerical methods with focus on underground mine tunnels.The close agreements between models have indicated that the thermal insulation applied on tunnel surfaces is able to provide promising heat abatement effects.展开更多
We have studied three plans for re-use of the abandoned mine roadway tunnels as an energy center. These are the thermostat plan, the thermal accumulator plan, and the CAES plan. Calculations show that the thermostat p...We have studied three plans for re-use of the abandoned mine roadway tunnels as an energy center. These are the thermostat plan, the thermal accumulator plan, and the CAES plan. Calculations show that the thermostat plan can provide over 15,000 m2 of building air-conditioning/heating load for each kilo- meter of roadway, but electric power is needed to run the system. Numerical research proved that the accumulation of hot water in the roadway for seasonal heating purposes （a temperature swing from 90 to 54 ℃） is a viable possibility. The CAES plan proposes using the discarded coal mine tunnel as a pea ing power station with an energy storage density over 7000 kj/m3. It can be concluded that presently abandoned coal mines could be reformed into future energy centers for a city.展开更多
In order to research spread law and distribution law of temperature nearby fire sources on roadway in mine, according to combustion theory and other basic, the theory model of temperature attenuation was determined un...In order to research spread law and distribution law of temperature nearby fire sources on roadway in mine, according to combustion theory and other basic, the theory model of temperature attenuation was determined under unsteady heat-exchange between wind and roadway wall. The full-size roadway fire simulation experiments were carried out in Chongqing Research Institute of China Coal Technology & Engineering Group Corporation. The development processes of mine fire and flow pattern of high temperature gas were analyzed. Experimental roadway is seen as physical model, and through using CFD software, the processes of mine fire have been simulated on computer. The results show that, after fire occurs, if the wind speed is less than the minimum speed which can prevent smoke from rolling back, then the smaller wind speed can cause smoke to roll back easily. Hot plume will lead to secondary disasters in upwind side. Because of roadway wall, hot plume released from roadway fire zone has caused the occurrence of the ceiling jet, and the hot plume has been forced down. Whereas, owing to the higher temperature, buoyancy effect is more obvious. Therefore, smoke rises gradually along the roadway in the flow process, and the hierarchical interface appears wavy.Oxygen-enriched combustion and fuel-enriched combustion are the two kinds of combustion states of fire. The oxygen content of downwind side of fire is maintained at around 15% for oxygen-enriched combustion, and the oxygen content of downwind side of fire is maintained at around 2% for fuel-enriched combustion. Furthermore, fuel-enriched combustion can lead to secondary disasters easily.展开更多
基金Project 50490274 supported by the National Natural Science Foundation of China
文摘Specimens of steel fiber reinforced concrete （SFRC） in volume ratios of 0%, 0.5%, 1% and 1.5% were prepared to study the supporting effect of SFRC at these diffterent volume ratios in a deep soft rock tunnel. Experiments with mechanical properties of compressive strength in cubic specimens, cleave strength in cylindrical specimens and four-point flexure strength of sheet metal specimens were carded out. The experimental results indicate that SFRC in a volume ratio of 1% is superior in ranking to other volume ratios in terms of technique and economics. By means of a numerical simulation, given the characteristics of soft rock deformation and damage at great depth, a new support substitution scheme of SFRC to replace plain concrete is proposed. The results of an industrial trial show that the support provided by SFRC can withstand large deformations of the surrounding rock. Good resuits have been obtained in a practical anplication.
基金The financial support from an Engage Grant in the Natural Sciences and Engineering Research Council(NSERC),Canada,is gratefully acknowledged
文摘The heat How generated from the infinite rock mass surrounding the underground tunnels is a major cause for the increasing cooling demands in deep mine tunnels.Insulation layers with lower thermal conductivities on tunnel walls and roof ceilings are believed to supply a thermo-barrier for heat abatement.However,it is found that no systematic theoretical investigations were made to predict and confirm the effectiveness of underground thermal insulation.Specifically,investigations on the underground insulation problems involving heat flows through the semi-infinite hot rock mass and insulation layer were not sufficient.Thus,in this paper,the thermal characteristics,accompanied with heat flow through the semi-infinite rock mass and the insulation layer,were modeled by both analytical and numerical methods with focus on underground mine tunnels.The close agreements between models have indicated that the thermal insulation applied on tunnel surfaces is able to provide promising heat abatement effects.
基金supported financially by the National Natural Science Foundation of China (No. 50908225)
文摘We have studied three plans for re-use of the abandoned mine roadway tunnels as an energy center. These are the thermostat plan, the thermal accumulator plan, and the CAES plan. Calculations show that the thermostat plan can provide over 15,000 m2 of building air-conditioning/heating load for each kilo- meter of roadway, but electric power is needed to run the system. Numerical research proved that the accumulation of hot water in the roadway for seasonal heating purposes （a temperature swing from 90 to 54 ℃） is a viable possibility. The CAES plan proposes using the discarded coal mine tunnel as a pea ing power station with an energy storage density over 7000 kj/m3. It can be concluded that presently abandoned coal mines could be reformed into future energy centers for a city.
基金Projects(51274099,51474106)supported by the National Natural Science Foundation of ChinaProject(10C0660)supported by the Scientific Research Fund of Hunan Provincial Education Department,China
文摘In order to research spread law and distribution law of temperature nearby fire sources on roadway in mine, according to combustion theory and other basic, the theory model of temperature attenuation was determined under unsteady heat-exchange between wind and roadway wall. The full-size roadway fire simulation experiments were carried out in Chongqing Research Institute of China Coal Technology & Engineering Group Corporation. The development processes of mine fire and flow pattern of high temperature gas were analyzed. Experimental roadway is seen as physical model, and through using CFD software, the processes of mine fire have been simulated on computer. The results show that, after fire occurs, if the wind speed is less than the minimum speed which can prevent smoke from rolling back, then the smaller wind speed can cause smoke to roll back easily. Hot plume will lead to secondary disasters in upwind side. Because of roadway wall, hot plume released from roadway fire zone has caused the occurrence of the ceiling jet, and the hot plume has been forced down. Whereas, owing to the higher temperature, buoyancy effect is more obvious. Therefore, smoke rises gradually along the roadway in the flow process, and the hierarchical interface appears wavy.Oxygen-enriched combustion and fuel-enriched combustion are the two kinds of combustion states of fire. The oxygen content of downwind side of fire is maintained at around 15% for oxygen-enriched combustion, and the oxygen content of downwind side of fire is maintained at around 2% for fuel-enriched combustion. Furthermore, fuel-enriched combustion can lead to secondary disasters easily.
