A Study on Geometric Design Parameters of Grille Sunshades in Highway Tunnels
(1. School of Civil Engineering, Southwest Jiaotong University, Chengdu 610031; 2. Key Laboratory of Transportation Tunnel Engineering, Ministry of Education, Southwest Jiaotong University, Chengdu 610031; 3. China Railway 14th Bureau Group Co., Ltd.,Jinan 250101)
Abstract：
In order to improve the design parameters of the grille sunshade, vehicle tests are carried out in the tun? nel group section of the Ya′an-Kangding expressway with an eye tracker. The change rate of the driver′s pupil diameter and the driver′ s subjective comfort were used as evaluation indicators to verify the shading effect of the grille sunshade. On this basis, two types of grid sunshade models, annular and portal, are built with DIAlux software.The shading rate of grill sunshade under different portal directions and different grill spaces is calculated, and the influence of different parameters on the shading effect of the sunshade is explored. Based on the relationship between the driver′s pupil area at the tunnel portal and the ambient illumination, the illumination requirements for different positions in the sunshade at different design speeds are given. The research shows that the grille sunshade effectively improves the driver′ s visual comfort at the entrance and exit of the tunnel. There is no obvious difference in shading effect between circular and portal sunshades. Affected by the natural light and the dark environment in the tunnel, there is a drastic transition between light and dark within the range of 5~10 m at both ends of the sunshade. The illumination of the middle section of the sunshade is relatively stable, which can be used as the basis for calculating the shading rate of the grille sunshade. The portal orientation has a great influence on the shading effect,and the shading rate of the east-west portal orientation is 5%~10% higher than that of the north-south portal orientation. Linear reduction is not the best option for gradual light reduction in the sunshade. The value can be calculated according to the relationship between illuminance and speed and the distance from the portal or according to the field illuminance test results.
YU Li1,
2 WANG Song1,
2 LUO Xiang1 etc
.A Study on Geometric Design Parameters of Grille Sunshades in Highway Tunnels[J] MODERN TUNNELLING TECHNOLOGY, 2023,V60(1): 34-46
2023, Vol. 60 