Study On Numerical Simulation Of Ventilation And Smoke Exhaust In New Tunnel Of Three Gorges

The Yangtze River Channel is the most important east-west axis of China's territorial space development,and plays an important strategic role in the overall pattern of national regional development.Under the background of sustained and stable economic development and continuous improvement of navigation conditions in the upper reaches of the Yangtze River,the freight volume of the Three Gorges Dam is increasing continuously,but the navigation capacity of the Three Gorges Ship Lock can not meet the current demand,so it is urgent to build a new Three Gorges Shipping Tunnel to alleviate the shipping pressure of the Yangtze River.On the premise of considering the river regime and topographic conditions,the connection of upstream and downstream routes,the length of the straight section of the ship lock,and the land occupation immigration,the relevant experts have preliminarily designed the routes of five new tunnels in the Three Gorges Dam area.On the basis of summarizing the research results of some experts and scholars on tunnel fire,the author establishes a full-scale numerical simulation model on the basis of line IV.The smoke exhaust effect of vertical ventilation mode with centralized vertical ventilation in the new tunnel of the Three Gorges is numerically simulated.The heat release rates of the fire include 300 MW,100 MW and 50 MW,the location of the fire includes a sluice chamber,a second sluice chamber and a third sluice chamber,the following results have been achieved:(1)When the number of one side of the smoke vent is 2 and the distance between the smoke exhaust is 330 m(that is,two smoke vents on one side are evenly arranged along the longitudinal direction of the tunnel),the ventilation and smoke exhaust effect is relatively optimal.In this thesis,there are three kinds of smoke vent spacing: one is to set the smoke vent along the longitudinal average,the distance between two smoke vents on one side is about 330m;Secondly,on the basis of 330 m,the two exhaust ports move to the nearby ports until the distance between the two ports is 450 m,the exhaust outlets are located in the brake chambers on both sides now;The third is to set two smoke vents in the middle of the tunnel.The distance between the two smoke vents is about 0m,and the two smoke vents are in the middle gate chamber.(2)The exhaust effect of a single smoke vent area of 22.5 m2 is optimal.There are three types of exhaust outlets involved in the thesis,namely 22.5m2,33.75m2 and 67.5m2.After comprehensive comparison,the appropriate single smoke vent area is 22.5m2.(3)The fire fighting strategy and personnel rescue strategy of the tunnel in the new channel of the Three Gorges are put forward.It is suggested to use automatic fire gun for fire fighting,steel ramps should be installed on the side walls of tunnels or embedded side-wall stairs should be constructed directly to guide people to evacuate and escape from the tunnel platform.