NUMERICAL SIMULATION OF FLOODING INTRUSION FLOW CHARACTERISTICS ON STAIRCASE WITH THE EFFECT OF REST PLATFORM

摘要

To evaluate the effect of rest platform on the safe evacuation of evacuator under underground flooding events, a numerical model of staircase with two rest platforms were developed to simulate the flow characteristics of the flooding intrusion flow on staircase with rest platform. The model was solved by the commercial software and validated by the experimental data and the available data of previous works for flow on staircases and stepped spillways. In order to make sure the formation of the air cavity under the nappe tongue downstream the rest platform, the ventilation gap opened at the step vertical face was introduced in the numerical model. As a result, the hydraulic characteristics of nappe tongue (the shape, the thickness and the drop length) and the cavity sub-pressure agree with the measured data and the available theoretical data well, the transversal velocity profiles of fully developed flow on staircase meet the rule of the skimming flow on the stepped spillway and present a good similarity. The simulated results also show that the nappe occurs and the velocity magnitude increases downstream the platform due to the existence of the rest platform. This phenomenon would cause negative effects on the safe evacuation for people evacuating from the underground space through a flooding staircase with a rest platform.