| Rapid progress has been made in the construction of highway tunnels in the last ten years in China. Great difficulties and higher demands have been emerged on ventilation technology during the construction of longer and longer tunnels. Based on the extra-long highway tunnel in Qinling mountains in Shannxi Province(18,020 meters in length), and the highway tunnel in Qidaoliang mountains in Gansu Province(4,000 meters in length), and the highway tunnel in Xuefeng mountains in Hunan Province(7,000 meters in length), the paper eager to the research on the ventilation technology of highway tunnel and the write of a network compute procedure of ventilation for highway tunnel.Nowadays, more and more multi-shafts ventilation systems have been applied in highway tunnels in the world, such as Kan-etsu tunnel, which is the longest tunnel in Japan with two vertical shafts, Tokyo Gulf undersea tunnel with one vertical shaft, and Laerdal tunnel with only one shaft in Norway is the longest tunnel so far built in the world. There is only one tunnel in the world with three or more shafts and with blowing and exhausting longitudinal ventilation system, which is in Taiwan, namely Pinglin tunnel (three shafts, 12,900 meters in length). Therefore, the Qinling extra-long highway tunnel may be of the largest scale in the world, which include three or four shafts blowing and exhausting longitudinal ventilation, utilizing parallel piloting train piston wind in railway tunnel, and a group of small shafts without power as comparison of ventilation schemes. It's significant to study the ventilation systems.In order to solve the difficulties in calculation of complicated ventilating system in highway tunnels, the paper introduces the ventilating network theory and establishes network mathematical models of pressure calculation in shafts. Momentum law is taken into consideration in local and loop of draught to establish the model. In the paper, many productions have been doon, e.g. ①the pressure formulas for ventilation resistance about positive and reverse blowing, positive and reverse exhaust have been deduced, ②blowing and exhausting shaft network model have been established, ③directionality simulation of blowing and exhausting wind flow in tunnel have been resolved successfully, ④especially simulation were done well for promoting pressure of air jet at a high speed in blowing outlet. It has been more closer between simulation operating mode and real state for the application ofthe model in the tunnel ventilating network technology into blowing and exhausting ventilation of highway tunnel.In deeply embedded tunnel, the depth of the shaft is up to several hundred meters. As the temperature of terrestrial heat power affects ventilation system remarkably, ventilation network terrestrial heat model have been established comparatively perfect in the paper, which can reflect the contribution of natural wind factors better such as ground temperature difference of hot location and exceeding static differential pressure between ports to highway tunnel ventilating system.Disaster precaution and relief during tunnel fire is a very impotent problem, which must be paid attention to in ventilation design and calculation in deep shaft of highway tunnel. The high temperature and gas in fire will produce very greet pressure of hot air in the deep shaft. A dynamic ventilating network fire model has been established in the paper, in which the pressure changes with some factors such as ventilation speed in highway tunnel. It can realize dynamic air pressure simulation in fire location better such as throttle effects in different fire locations and buoyancy effect of contaminated area fire.Researching systemically on the ventilation technological characteristic of highway tunnel, an entire model of highway tunnel ventilation network has been established, which includes six special models (natural wind resistance model, traffic wind pressure model, axial fan model, jet fan model, traffic wind pressure model, dynamic model of fire pressure), and also a complicated highway tunnel ventilation network calculating procedure has been developed. The procedure, in Visual Basic language, include three functions: ? dividing wind calculation for ventilation network, ?network fan disposition . @fire operating mode simulation calculation when the tunnel is open to traffic. The procedure also has very strong data tracing and error-correcting functions.The procedure has been applied in the research of operating ventilation technologies for the Qinling extra-long highway tunnel, provided powerful support for ventilation system design and comparison of methods, and providing reliable data for optimization design of ventilation system for the Qidaoliang highway tunnel and the Xuefengshan highway tunnel in the analysis of operational ventilation and fire precaution.In order to obtain sufficient data and information for ventilation design andcalculation, plentiful field tests have been made on special items— ventilation resistance factor and distribution rule of air temperature in the multi-shaft tunnels and climate changes between tunnel portals etc. which ensure the safety of ventilating calculation and design.Also, computing fluid dynamical technology has been employed to analyze three-dimension model on local ventilation simulation of blowing and exhausting shaft in the paper, which validates correctness of local network model of blowing and exhausting shaft.Finally, the paper checks the calculating results of complex ventilation network calculation procedure in highway tunnel. Comparison between the calculating results by using the procedure mentioned above and the conventional methods specified by the "Specifications for Design of Ventilation and Lighting of Highway Tunnel (JTJ 026.1-1999)", which proves the reliability of the network calculation procedure. The factor e.g. different traffic volumes, different traffic velocities and dual direction traffic situations are considered in the calculations, which show that the procedure has comprehensive analysis functions.
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