公路隧道运营环境的二氧化碳分布特性

Carbon dioxide distribution characteristics of highway tunnel operating environment

为了探究公路隧道运营环境中CO_(2)的分布特性,基于宁波市5处公路隧道的现场实测,研究公路隧道运营环境的CO_(2)体积分数基本水平以及CO_(2)体积分数与隧道交通流状态、平面线形、断面几何特性等的关系.基于4G远程智能化连续监测,分析公路隧道运营环境CO_(2)体积分数随时间的变化.通过数值模拟探讨隧道长度、线形、交通流状态及断面几何特性等对CO_(2)分布的具体影响规律.研究发现,CO_(2)体积分数沿隧道纵向具有明显的线性递增特征,通常情况下隧道出口处的CO_(2)体积分数最高,可达691×10^(−6)~1226×10^(−6),为一般大气环境水平的2~4倍,同交通量情况下通风水平、横通道、加宽带、线形、长度等会提高线性增长的斜率且影响程度依次递减.CO_(2)的断面分布具有明显的扩散现象和重力效应,同一断面的壁面高度越大,体积分数越小,直线隧道两侧的CO_(2)呈对称分布,曲线隧道内侧的体积分数显著高于外侧,加宽带具有一定的缓冲效应且加宽带一侧体积分数略低于另一侧,横通道具有一定的互补式通风效果.CO_(2)体积分数具有明显的时变特征和周期性,8点、12点、17点出现日体积分数极值,周末出现周体积分数极值,体积分数变化与交通量情况显著相关.

The basic level of carbon dioxide volume fraction in the operating environment of highway tunnels and the relationship between carbon dioxide volume fraction and tunnel traffic flow state,plane alignment and crosssection geometric characteristics were analyzed based on the field measurement of five highway tunnels in Ningbo in order to explore the distribution characteristics of carbon dioxide in the operating environment of highway tunnels.The change of carbon dioxide volume fraction in highway tunnel operation environment with time was analyzed based on 4G remote intelligent continuous monitoring.The specific influence of tunnel length,alignment,traffic flow state and section geometric characteristics on the distribution of carbon dioxide was discussed by numerical simulation.Results showed that the volume fraction of carbon dioxide had obvious linear increasing characteristics along the longitudinal direction of the tunnel.Generally,the volume fraction of carbon dioxide at the exit of the tunnel was the highest,up to 691×10^(−6)~1226×10^(−6),which was 2~4 times that of the general atmospheric environment level.Ventilation level,cross channel,broadband,line shape and length will increase the slope of linear growth and the degree of influence will decrease in turn under the same traffic volume.The cross-section distribution of carbon dioxide has an obvious diffusion phenomenon and gravity effect.The higher the wall height of the same section is,the lower the volume fraction is.The volume fraction of carbon dioxide on both sides of the straight tunnel is symmetrically distributed.The volume fraction inside the curve tunnel is significantly higher than that on the outside.The broadband has a certain buffer effect and the volume fraction on the broadband side is slightly lower than that on the other side.The cross channel has a certain complementary ventilation effect.The volume fraction of carbon dioxide has obvious time-varying characteristics and periodicity.The daily volume fraction extreme value appears at 8,12 and 17 o’clock,and the weekly volume fraction extreme value appears at the weekend.The volume fraction change is significantly correlated with the traffic volume.