海底隧道三洞并行施工通风方案优化研究

Research on the Ventilation Scheme of 3 Holes Parallel Construction in Subsea Tunnel

研究目的:针对钻爆法施工有害气体扩散规律的研究,目前对单洞独头掘进研究较多,对“三洞并行”施工通风研究较少。为探究海底隧道三洞并行施工较优的通风方案并优化风机布置,以青岛胶州湾第二海底隧道工程为依托,重点对海域钻爆段“三洞并行”施工污染物运移规律进行研究。通过建立“双孔大断面正洞+小断面服务隧道”的“三洞并行”三维模型,使用FLUENT软件三维紊态RNG k-ε模型和组分输运模型模拟隧道爆破后CO浓度分布,分析三种通风方案下CO浓度场变化规律,在此基础上对横通道射流风机布置进行优化。研究结论:(1)三洞并行工况下,利用中间服务隧道可以有效排出多个工作面钻爆施工产生的污染物,但在横通道区域会有污染物滞留现象;(2)在服务隧道内加入射流风机后,全程无明显CO滞留现象,并且可以明显降低浓度峰值,加快CO排出浓度速率;(3)距离横通道中心10 m处为横通道射流风机最佳放置位置;(4)本研究成果可为相关海底隧道施工通风的设计与施工提供参考和借鉴。

Research purposes:At present,aiming at the diffusion law of harmful gas in drilling and blasting construction,there are more studies on single tunnel blind heading,but the ventilation scheme of 3 holes parallel construction is rarely studied.In order to explore the optimal ventilation scheme for the parallel construction of the three-hole subsea tunnel and optimize the fan arrangement,based on the second subsea tunnel in Qingdao-Jiaozhou Bay,this paper focuses on the pollutant transport law of 3 holes parallel construction in the drilling and blasting section in the sea area.In this paper,the 3 D model of 3 holes parallel-double large section main tunnel+small section service tunnel-are established.The CO concentration distribution after tunnel blasting is simulated by the 3 D turbulent RNG k-εmodel and component transport model in FLUENT.And the variation law of CO concentration under three ventilation schemes is analyzed.On this basis,the distribution of cross channel jet fan is optimized.Research conclusions:(1)Under the condition of 3 holes parallel construction,through the intermediate service tunnel,the pollutants produced by drilling and blasting construction of multiple working faces can be effectively discharged.However,there will be pollutant retention in the cross channel area.(2)After the jet fan is added into the service tunnel,there is no obvious CO retention in the whole process.And the concentration peak can be significantly reduced and the discharge concentration rate of CO can be accelerated.(3)The best position of jet fan is 10 m away from the center of cross passage.(4)The research results can provide reference for the design and construction of related subsea tunnel.