Drainage ventilation systems for underground structures II: simulation of transient response.

The propagation of low-amplitude air pressure transients within the drainage and vent systems of underground habitable structures may result in system failure due to trap seal loss and foul odour ingress into the occupied space. This paper develops the simulation of such transient response, and presents comparisons between predicted system air pressures and those monitored during the operation of the drainage and vent system in a large London Underground tube railway station. The use of the model to investigate system operating regimes ahead of installation as a direct design aid is demonstrated.