Study On Influence Of Slope Blocking On Smoke Characteristic Parameters Of Highway Tunnel

Highway tunnel is a typical building with limited and long underground space.In the event of a car accident,mass casualties are more likely to occur than in a wide space.Therefore,it is very important to master the transportation law of smoke in tunnel and control the movement of smoke to reduce casualties and property losses after tunnel fire.According to the literature survey,most previous researches in the field of tunnel fire only consider the influence of single factor.However,in fact,the characteristic parameters of tunnel smoke are affected by many factors.Different from previous studies,this study combines theoretical analysis with size reduction experiment.In this paper,a horseshoe tunnel model with a different rectangular section is adopted to study the countercurrent length and critical wind speed of smoke in a horseshoe highway tunnel under the combined action of slope blocking.The research contents of the smoke movement characteristic parameters of highway tunnel are divided into four parts.In this paper,a 1:10 scale model is built based on the Froude similarity criterion for a real tunnel.Firstly,the variation law of smoke in a flat slope non blocking tunnel is studied by using the scale model.The prediction models of dimensionless countercurrent length and dimensionless critical wind speed were obtained.Compared with the previous research results,it is found that the prediction model of this study is not consistent with the previous prediction model,which is mainly caused by the different geometric dimensions and wall materials of the model;Then,the influence of blockage ratio on flue gas movement is analyzed.The larger the blockage ratio is,the shorter the countercurrent length is.Based on the analysis of the data,the prediction models of dimensionless countercurrent length and dimensionless critical wind speed were found;By changing the slope of the model,the law of smoke movement under the condition of non blocking slope was studied.The results show that the larger the slope is,the shorter the countercurrent length is.Based on the slope correction coefficient,the dimensionless smoke countercurrent length and dimensionless critical wind speed prediction model of inclined tunnel are obtained;Finally,the smoke movement law under the combined action of two factors is studied.Based on the analysis of the data,the prediction model of dimensionless countercurrent length and dimensionless critical wind speed was obtained.