To realize a stable addition of foaming agent used for foam technology, a new adding method using the jet cavitation was introduced, and its performance was investigated experimentally under different operating condit...To realize a stable addition of foaming agent used for foam technology, a new adding method using the jet cavitation was introduced, and its performance was investigated experimentally under different operating conditions. Experimental results show that the bubble region in the jet device has a constant vapor pressure, which creates a good condition for liquid absorption, while it shrinks with increasing outlet pressure. The liquid absorption amount keeps unchanged when the outlet pressure is lower than a critical value. The critical outlet pressure increases by 40% with decreasing cavitation absorption amount, which is especially suitable for mini-flow quantitative addition of foaming agent used for foam dust suppression. Its effectiveness on suppressing mine dust was evaluated in a heading face of underground coal mines. Field application indicates that the reliable and simple foaming system adopting the new adding method makes a marked dust suppression effect. The working environment of heading face is significantly improved, ensuring the safe tunneling and personal security.展开更多
The advantages and disadvantages of various outburst prevention measures inheading face were analyzed.The mechanism of outburst prevention about hydraulic extrusionmeasure was studied, the technological parameters wer...The advantages and disadvantages of various outburst prevention measures inheading face were analyzed.The mechanism of outburst prevention about hydraulic extrusionmeasure was studied, the technological parameters were introduced, and the effectof outburst prevention was investigated.The in-situ experimental results show that thehydraulic extrusion measures are applied in serious outburst mine, not only the stress ofstimulate outburst is eliminated effectively but also the gas in coal seam is released efficiently,the measures get obvious effect on coal and gas outburst prevention, and theroadway driving speed is increased by 1.5 times, implementing a safe and rapid excavation.展开更多
The layout of the buckets for tunnel boring machine(TBM)directly affects the muck removal efficiency of cutterhead during excavation.In order to improve the muck removal performance for TBM,the optimal design of bucke...The layout of the buckets for tunnel boring machine(TBM)directly affects the muck removal efficiency of cutterhead during excavation.In order to improve the muck removal performance for TBM,the optimal design of bucket layout was investigated.The whole muck transfer process was simulated by discrete-element method(DEM),including the muck falling,colliding,pilling up,shoveling and transferring into the hopper.The muck model was established based on size distribution analysis of muck samples from the water-supply tunnel project in Jilin Province,China.Then,the influence of the bucket number and the interval angle between buckets on muck removal performance was investigated.The results indicated that,as the number of buckets increased from four to eight,the removed muck increased by 29%and the residual volume decreased by 40.5%,and the process became steadier.Different interval angles between buckets were corresponding to different removed muck irregularly,but the residual muck number increased generally with the angles.The optimal layout of buckets for the cutterhead in this tunnel project was obtained based on the simulation results,and the muck removal performance of the TBM was verified by the actual data in the engineering construction.展开更多
基金Project(51474216)supported by the National Natural Science Foundation of ChinaProject supported by the Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions,ChinaProject(2012DXS02)supported by the Fundamental Research Funds for the Central Universities,China
文摘To realize a stable addition of foaming agent used for foam technology, a new adding method using the jet cavitation was introduced, and its performance was investigated experimentally under different operating conditions. Experimental results show that the bubble region in the jet device has a constant vapor pressure, which creates a good condition for liquid absorption, while it shrinks with increasing outlet pressure. The liquid absorption amount keeps unchanged when the outlet pressure is lower than a critical value. The critical outlet pressure increases by 40% with decreasing cavitation absorption amount, which is especially suitable for mini-flow quantitative addition of foaming agent used for foam dust suppression. Its effectiveness on suppressing mine dust was evaluated in a heading face of underground coal mines. Field application indicates that the reliable and simple foaming system adopting the new adding method makes a marked dust suppression effect. The working environment of heading face is significantly improved, ensuring the safe tunneling and personal security.
文摘The advantages and disadvantages of various outburst prevention measures inheading face were analyzed.The mechanism of outburst prevention about hydraulic extrusionmeasure was studied, the technological parameters were introduced, and the effectof outburst prevention was investigated.The in-situ experimental results show that thehydraulic extrusion measures are applied in serious outburst mine, not only the stress ofstimulate outburst is eliminated effectively but also the gas in coal seam is released efficiently,the measures get obvious effect on coal and gas outburst prevention, and theroadway driving speed is increased by 1.5 times, implementing a safe and rapid excavation.
基金Project(51475478)supported by the National Natural Science Foundation of ChinaProject(2012AA041801)supported by the National High Technology Research and Development Program of China+1 种基金Project(2014FJ1002)supported by the Science and Technology Major Project of Hunan Province,ChinaProject(2013CB035401)supported by the National Basic Research Program of China。
文摘The layout of the buckets for tunnel boring machine(TBM)directly affects the muck removal efficiency of cutterhead during excavation.In order to improve the muck removal performance for TBM,the optimal design of bucket layout was investigated.The whole muck transfer process was simulated by discrete-element method(DEM),including the muck falling,colliding,pilling up,shoveling and transferring into the hopper.The muck model was established based on size distribution analysis of muck samples from the water-supply tunnel project in Jilin Province,China.Then,the influence of the bucket number and the interval angle between buckets on muck removal performance was investigated.The results indicated that,as the number of buckets increased from four to eight,the removed muck increased by 29%and the residual volume decreased by 40.5%,and the process became steadier.Different interval angles between buckets were corresponding to different removed muck irregularly,but the residual muck number increased generally with the angles.The optimal layout of buckets for the cutterhead in this tunnel project was obtained based on the simulation results,and the muck removal performance of the TBM was verified by the actual data in the engineering construction.
