Wall-mounted swirling ventilation is a new type of system in mechanized excavation faces with a dust sup-pression performance that is closely related to the blowing-to-suction flow ratio.Physical and simulation models...Wall-mounted swirling ventilation is a new type of system in mechanized excavation faces with a dust sup-pression performance that is closely related to the blowing-to-suction flow ratio.Physical and simulation models were developed according to the No.C103 mechanized excavation face in the Nahe Coal Mine of the Baise Mining Bureau,Guangxi Province to optimize the blowing-to-suction flow ratio for wall-mounted swirling ventilation.Both the k-εturbulence model and the discrete phase model were utilized to simulate airflow field structures and dust concentration distribution patterns at various blowing-to-suction flow ratios.The results suggest that higher blowing-to-suction flow ratios increase the airflow field disturbance around the working face and weaken the intensity of the axial air curtain.On the other hand,both the intensity of the radial air curtain and the dust suppression effect are enhanced.At a blowing-to-suction flow ratio of 0.8,the wall-mounted swirling ventilation system achieved the most favorable dust suppression performance.Both the total dust and respirable dust had their lowest concentrations with maximum efficiencies of reducing both types at 90.33%and 87.16%,respectively.展开更多
To solve the problem of excavation face dust control,the theory of dust removal after collection was put forward.Through a large number of theoretical and experimental researches,a new wind screen dust-collection syst...To solve the problem of excavation face dust control,the theory of dust removal after collection was put forward.Through a large number of theoretical and experimental researches,a new wind screen dust-collection system which was applied to comprehen- sive excavation face was developed.To set a wind dam in jet stream box,achieve the function of multi-stage and multiple-level regulation,lots of experimentation was carried out to obtain higher jet stream velocity with the minimum loss of energy.Experiments show that the slit width in the exports of wind screen dust-collection system should be 10 to 15 mm.For the general excavation roadway,after wind attenuation,the velocity can be greater than 3 m/s at the roof which meets the requirements of respirable dust control.展开更多
Following a few preliminary remarks on the tunneling methods at the beginning of the 20th century, thesuccessful applications of the full-face method also in difficult conditions are underlined. The attention isposed ...Following a few preliminary remarks on the tunneling methods at the beginning of the 20th century, thesuccessful applications of the full-face method also in difficult conditions are underlined. The attention isposed on the use of a systematic reinforcement of the face and of the ground, by means of fiber-glasselements. A selection of tunnels where this method was used successfully is reported with the purposeof illustrating the wide spectrum of ground conditions where it has been applied. Then, following adescription of the main concepts behind the method, the attention moves from the so-called “heavymethod”, where deformations are restrained, to the “light method”, where deformations are allowedwith the intention to decrease the stresses acting on the primary and final linings. The progress in theapplication of the “light method” is underlined, up to the development of a novel technique, which relieson the use of a yielding support composed of top head steel sets with sliding joints and specialdeformable elements inserted in the primary lining. The well-known case study of the Saint Martin LaPorte access adit, along the Lyon-Turin Base Tunnel, is described. In this tunnel, a yield-control supportsystem combined with full-face excavation has been adopted successfully in order to cope with the largedeformations experienced during face advance through the Carboniferous formation. The monitoringresults obtained during excavation are illustrated, together with the modeling studies performed whenpaying attention to the rock mass time-dependent behavior.展开更多
基金support for this work was provided by the National Natural Science Foundation of China(No.51574123)the Scientific Research Project of Hunan Province Office of Education(No.18A185),which are gratefully acknowledged.
文摘Wall-mounted swirling ventilation is a new type of system in mechanized excavation faces with a dust sup-pression performance that is closely related to the blowing-to-suction flow ratio.Physical and simulation models were developed according to the No.C103 mechanized excavation face in the Nahe Coal Mine of the Baise Mining Bureau,Guangxi Province to optimize the blowing-to-suction flow ratio for wall-mounted swirling ventilation.Both the k-εturbulence model and the discrete phase model were utilized to simulate airflow field structures and dust concentration distribution patterns at various blowing-to-suction flow ratios.The results suggest that higher blowing-to-suction flow ratios increase the airflow field disturbance around the working face and weaken the intensity of the axial air curtain.On the other hand,both the intensity of the radial air curtain and the dust suppression effect are enhanced.At a blowing-to-suction flow ratio of 0.8,the wall-mounted swirling ventilation system achieved the most favorable dust suppression performance.Both the total dust and respirable dust had their lowest concentrations with maximum efficiencies of reducing both types at 90.33%and 87.16%,respectively.
基金the National Natural Science Foundation of China(f010206)
文摘To solve the problem of excavation face dust control,the theory of dust removal after collection was put forward.Through a large number of theoretical and experimental researches,a new wind screen dust-collection system which was applied to comprehen- sive excavation face was developed.To set a wind dam in jet stream box,achieve the function of multi-stage and multiple-level regulation,lots of experimentation was carried out to obtain higher jet stream velocity with the minimum loss of energy.Experiments show that the slit width in the exports of wind screen dust-collection system should be 10 to 15 mm.For the general excavation roadway,after wind attenuation,the velocity can be greater than 3 m/s at the roof which meets the requirements of respirable dust control.
文摘Following a few preliminary remarks on the tunneling methods at the beginning of the 20th century, thesuccessful applications of the full-face method also in difficult conditions are underlined. The attention isposed on the use of a systematic reinforcement of the face and of the ground, by means of fiber-glasselements. A selection of tunnels where this method was used successfully is reported with the purposeof illustrating the wide spectrum of ground conditions where it has been applied. Then, following adescription of the main concepts behind the method, the attention moves from the so-called “heavymethod”, where deformations are restrained, to the “light method”, where deformations are allowedwith the intention to decrease the stresses acting on the primary and final linings. The progress in theapplication of the “light method” is underlined, up to the development of a novel technique, which relieson the use of a yielding support composed of top head steel sets with sliding joints and specialdeformable elements inserted in the primary lining. The well-known case study of the Saint Martin LaPorte access adit, along the Lyon-Turin Base Tunnel, is described. In this tunnel, a yield-control supportsystem combined with full-face excavation has been adopted successfully in order to cope with the largedeformations experienced during face advance through the Carboniferous formation. The monitoringresults obtained during excavation are illustrated, together with the modeling studies performed whenpaying attention to the rock mass time-dependent behavior.
