Key Technology Study On Ventilation In High-Altitude Single-Hole Bidirectional Extra-Long Highway Tunnel

With the improvement of construction level, highway tunnels has a tendency to become extra-high and extra-long. The number of low-level single-hole bidirectional extra-long highway tunnels whose altitude exceeds 3000m receives a substantial growth. Due to the growth of the altitude, ventilation of these tunnels encounters technical difficulties. Construction process is seriously affected and the safety of people and property is threatened in construction stage, while the heavy expenses in operation stage also remain to be a serious problem. As the number of high-altitude low-level extra-long highway tunnels continues growing up, solution to the ventilation technical problems becomes more urgent and important.Based on a single-hole bidirectional highway tunnel (SBHT) called Balang Mountain tunnel with the altitude of 3850m and the length of 7954m, theoretical analysis, field measurement and numerical simulation were used to study ventilation design and operation energy-saving techniques of high-altitude extra-long highway tunnels. The results are obtained as follows:1.Calculation method of multi-vehicle smoke height coefficient applying to tunnels whose altitude exceeds 2400m and the one for the multi-vehicle CO height coefficient applying to tunnels whose altitude exceeds 2200m are established.2. Flat-directed indentation three-transverse-gallery resistance-reducing and ventilation energy-saving technique of high-altitude single-hole bidirectional extra-long highway tunnel is established, and the ventilation energy-saving technique under the precise control of fan based on different traffic volumes is established.3. Altitude modified method of fan efficiency is established by the research on the tunnel fan efficiency.4. Natural wind velocity formula without inclined shaft in high-altitude highway tunnel is demonstrated. Natural wind velocity data at all time during one year is obtained by filed test in meteorological station. Combined with mechanical ventilation in tunnel, energy-saving technique based on using natural wind in high-altitude single-hole bidirectional extra-long highway tunnel (HSBEHT) is established.