公路隧道洞口结构因素对废气窜流的影响

Effect of Structural Factors on Waste Gas Cross Flowing Around Portal of Highway Tunnels

为了给减弱公路隧道洞口废气窜流提供洞口土建结构设计方案,对洞口废气窜流影响的显著性因素进行了探讨,从洞口纵向错开不同距离、洞外设置不同位置及高度的挡壁等结构因素出发,借助计算流体动力学技术,进行了多因素异水平混合型数值模拟正交试验,探讨了不利自然风条件下洞外不同组合结构因素对洞口废气窜流的影响规律。结果表明:不同结构因素组合对废气窜流改善效果明显不同,洞口纵向错开改善窜流效果最为明显;在隧道出口侧设置有挡壁的所有组合结构均能较好地改善出口废气窜流,其中最有效的是同时在出口侧、中侧、入口侧设置与洞口等高的挡壁;仅在洞外中侧设置中间挡壁,其高度约为洞口高度的2倍时,可以有效改善废气窜流,其他情况下采用高挡壁结构的改善效果不佳;若同时在两隧道中侧与入口隧道侧设置挡壁则废气窜流改善效果差;若仅在入口隧道侧设置长挡壁,则加剧废气窜流。

In order to offer some references for building structure design of the highway tunnel portal which could reduce the waste gas cross flowing, some possible effective factors on waste gas cross flowing around portal of highway tunnel were studied. Based on CFD technique, orthogonal numerical simulation test on many factors and at different levels was carried out from structural aspects such as different distances of the two portals along vertical direction, different sizes and different places of block wall set up or not outside the tunnel. The influence laws of different combinations of structural factors outside the tunnel with effect on portal waste gas cross flowing were acquired under the disadvantageous natural wind. The result shows that the improvement effects vary under different combinations of structural factors. A proper interval distance of the two portals along vertical direction is most effective. A proper size of block wall set up at the exit of tunnel is considered more effective and block walls with equal height as the tunnel set up at the exit, entrance and between portals have the best effect. A block wall set up only between portals with height two times more than that of tunnel can be effective. Other cases are not effective. It is effectless if a block wall is set up between portals and at the entrance of the tunnel and it will deteriorate the waste gas cross flowing if only a long block wall is set up at the entrance,