郑万高铁巫山特长隧道长风室接力通风污染物运移特征研究

Pollutant Diffusion Law in Relay Ventilation of Long Ventilation Chamber in Wushan Tunnel on Zhengzhou-Wanzhou High-Speed Railway

为解决巫山特长隧道洞内作业空间污染物产量大、新污风置换效率低下、有害气体局部集聚严重等一系列环境问题,通过现场监测数据分析和全尺寸数值模拟方法研究长风室通风布设形式下,隧道单洞掘进、双洞协同掘进时CO和粉尘等污染物的动态运移特征和衬砌台车对粉尘扩散的阻碍作用。研究结果表明:1)隧道风流场稳定性受纵向回风速度大小干扰,当回风速度为0.5~0.7 m/s,风流场波动幅度相对较大,不利于污染物排出;2)CO扩散时,污染物以整体质量浓度降低的形式同步排出,单洞和双洞掘进情况下通风900 s可满足掌子面200 m范围内CO容许质量浓度要求;3)台车对爆破粉尘的扩散具有明显的阻碍作用,二次衬砌台车段整体降尘率较无台车施工段降低约42%,无台车情况相较于有台车情况,降尘效率约提升2.5倍。

During the construction of the Wushan extra-long tunnel,several environmental problems emerged.These included the large release of pollutants in the working space,inefficiency in replacing sewage wind,and dangerous local concentration of harmful gases.To address these challenges,the dynamic diffusion law of pollutants such as CO and dust is examined.This analysis is based on field monitoring data and employs a full-scale numerical simulation method.Moreover,the hindering effect of lining trolleys on dust diffusion is explored under various conditions,including singlehole tunneling,double-hole synergistic tunneling,and within a long ventilation chamber.The results reveal the following findings:(1)The air flow field stability is affected by the longitudinal return air velocity of the tunnel,leading to relatively large fluctuations in the air flow field within the 0.5~0.7 m/s range,hindering the pollutants′discharge.(2)Pollutant is ultimately discharged synchronously by decreasing the overall concentration when CO diffuses.The 900 s ventilation proves sufficient for the allowable CO concentration within 200 m of the working face during both singleand double-hole tunneling conditions.(3)The presence of a trolley has a remarkable blocking effect on the blasting dust diffusion,resulting in an approximate 42%lower overall dust reduction rate in the section with secondary lining trolleys compared to the construction section without the trolleys.Moreover,the dust reduction efficiency without a trolley is approximately 2.5 times higher than that with a trolley.