Single-channel blowing-in longitudinal ventilation method and its application in the road tunnel

Abstract

The longitudinal ventilation method is widely used in extra-long tunnels because of its simple ventilation mode and lower construction and operation costs. This paper originally proposes a new longitudinal ventilation method, the single-channel blowing-in longitudinal method. Only one ventilation channel is set between uphill line and downhill line of main tunnel, and relatively fresh air near the entrance of the downhill line is sent to the section close to the uphill line exit through the ventilation channel. The authors deduced the ventilation theory, design method and applicable conditions in detail, analyzing six cases to reveal the variation regulation of optimal location of single-channel xfit, one-year ventilation energy consumption Pone, total ventilation energy consumption Ptotal, and applicable scope of the tunnel length Lmax. The results suggest the following. (1) The optimal location of single-channel xfit enable the total ventilation energy consumption in serving period Ptotal to be the minimal, but usually it cannot let one-year energy consumption Pone reach the minimum. (2) The single-channel system makes full use of the surplus fresh air and the piston effect of traffic wind in the tunnel, showing a better energy-efficient property from a long-term perspective (3) For the whole serving period, xfit and Ptotal is relatively fixed when the traffic volume changes linearly. Meanwhile, this method has been successfully applied to China Mingtang Mountain Tunnel, and the relevant engineering application experience would be helpful for the similar projects.