Large Eddy Simulation of Construction Ventilation in Diversion Tunnels

• 1、State Key Laboratory of Hydraulic Engineering Simulation and Safety，Tianjin University，Tianjin 300072，China

Abstract：Construction ventilation is a key factor which influences the construction schedule and construction personnel health in diversion tunnels. Current researches in the field of ventilation numerical simulation of tunnel construction are limited to averaged flow field calculated by RANS, lacking reseach of fine and instantaneous change process of flow field. In this paper, a high-resolution three-dimensional grid by grid sensitivity analysis was built to simulate the dynamic development process of the construction ventilation in diversion tunnels with Large eddy simulation method. Instantaneous wind speed, wind pressure distribution results was obtained and campared with the result of RANS method.The results show that large eddy simulation can figure out a plurality of eddies in the 5th and 10th second of the ventilation, nevertheless, only one obvious eddy can be solved by the Reynolds time-averaged method. The wind flow nearly achieves stability in the 1200th second, and eddies near the working face can transitorily detain the pollutant. The average wind velocity on the respiratory zone height of working face is 0.91m/s, which conforms to the minimum wind speed standard of the criterion, and the pression of two high pressure areas formed on top and bottom of the working face can be 36Pa.

Keywords： diversion tunnel construction ventilation large eddy simulation