海底隧道独头钻爆施工通风三维数值分析

3D Numerical Simulation on Construction Ventilation of Subsea Tunnels with Single-head Drilling and Blasting

海底隧道长且竖井少,独头钻爆掘进距离长,施工通风问题突出。以青岛胶州湾第二海底隧道为依托,对钻爆法独头掘进施工的海域段隧道进行了压入式通风条件下掌子面附近风流流场、CO浓度场以及隧道内部粉尘扩散规律的研究。结果表明:根据掌子面处风速要求,风筒出风口距离掌子面40 m处是可行的;隧道通风后,涡流区域粉尘浓度分布不均,隧道风管一侧浓度明显大于另一侧,大部分粉尘在距离掌子面100 m内发生沉降和捕获;并根据CO浓度要求,确定了不同掘进距离和供风量情况下的进洞安全时间。

The long subsea tunnel has few shafts,and the single-head drilling and blasting has a long excavation distance,so the construction ventilation problem is prominent.Based on the second subsea tunnel of Jiaozhou Bay in Qingdao,the wind flow field,the CO concentration field near the tunnel face and the dust diffusion law in the tunnel under the condition of forced ventilation were carried out for research with the tunnel in the sea area excavated by the drill-and-blast method.The results show that it is feasible for the air outlet of the fan to be 40 m away from the face on the wind speed basis.Along with the tunnel is ventilated,the dust concentration distribution in the vortex area is uneven,and the concentration on one side of the tunnel air duct is significantly higher than that on the other side,and most of the dust settles and captures within 100 m from the tunnel face.According to the CO concentration requirements,the safe time for entering the hole under different driving distances and air supply volumes is determined.