Jet Ventilation For Super-long Tunnels And Ventilation Technology For Tunnels With Multiple Working Faces

Due to the development of underground space technology, the underground excavation space of traffic works, hydro-power works and Metro works grows larger and larger. During the construction of tunnels and underground works, it is of great importance to ensure the health of the construction workers. Construction ventilation is one of the major measures to ensure the health of the construction workers. Super-long Yuanliangshan tunnel is the first tunnel in China that has been excavated by drill and blast method and for which jet ventilation technology has been adopted through parallel pilot. The jet ventilation technology has provided satisfactory working environment for the tunnel construction.Construction jet ventilation belongs to gallery ventilation. Jet ventilation technology is a mature technology for tunnel operations; however, the air volume of the jet ventilation technology for tunnel constructions may vary because of the local fans. In the paper, non-linear equations are established on basis of the air routes in the ventilation networks and by means of the air pressure balance law and the air volume balance law, the air volumes of the construction jet ventilation are obtained, the effects on the air volumes of the local fans imposed by the locations of the jet ventilation fans are determined and the most energy-saving cross-gallery air flow control methods are decided.By taking comprehensive gas prevention and control measures, the safety of the construction of Yuanliangshan tunnel under gas conditions is guaranteed. By means of professional management of construction ventilations, the design of the construction ventilation is realized thoroughly and satisfactory ventilation effects are achieved. Finally, brief comments are made on the future research trends.On basis of the features of Yuanliangshan tunnel, jet ventilation technology has been successfully used in the construction of the tunnel and the calculation method for the air volumes of construction jet ventilations are improved. The calculation method for the air volumes of construction jet ventilations is not only suitable for gas tunnels consisting of twin tubes, but also suitable for long tunnels with ancillary adits and large-scale underground structures.