长大海底盾构隧道施工期环境温度分布实测分析及影响因素研究

Measurement and Influencing Factors of Environmental Temperature Distribution During Construction Period of Long and Large Submarine Shield Tunnels

为开展长大海底盾构隧道施工期独头通风流场分布及参数优化后环境降温效果研究,通过现场监测数据明确隧道沿程环境温度和风速特征,并对海底盾构隧道主要热源进行统计,建立长大海底盾构隧道施工期的温度场三维数值计算模型,探究盾构掘进长度、通风量和入口风温等因素对隧道环境温度场和通风死区分布的影响。研究结果表明:1)盾构主机和1号台架下层和中层设备为主要的散热源,设备后方的大范围通风死区处有局部异常高温;2)从盾构主机至始发井,隧道内回风风速先骤减再略微增加后基本保持稳定,通风量损失主要在盾构刀盘后配套作业区;3)隧道沿程环境温度呈骤降—缓降—缓升的变化规律;4)在盾构掘进长度小于6 km时,盾构主机处温度呈快速线性增大随后增速放缓的变化特征;5)通风死区范围随着盾构掘进长度和通风量的增加分别呈指数上升和指数衰减的趋势,加大通风量能有效消除隧道内通风死区。

Herein,the field monitoring method is performed to clarify the distribution of environmental temperature and ventilation flow field in a long and large submarine shield tunnel.Subsequently,the primary heat sources of submarine shield tunnels are identified and a three-dimensional numerical model of the temperature field is established.These steps investigate the effects of shield tunneling length,ventilation rate,and wind temperature on the temperature and ventilation blind zone distribution in the tunnel.The primary conclusion points are as follows:(1)The main machine of the shield and equipment on the lower and middle floors of the No.1 framework are the main heat sources.A large ventilation blind area behind the equipment exhibits a locally-high temperature.(2)The return air velocity in the area from the shield main machine to the launching shaft sharply decreases and then gradually increases before stabilizing.Air loss occurs mainly in the postshield support workarea.(3)The wind temperature undergoes a sudden decrease,followed by a gradual decrease and then a gradual increase.(4)When the excavation length of the shield is<6 km,the temperature at the shield main machine exhibits a rapid linear increase,which is followed by a slowdown in the growth rate.(5)The range of the ventilation blind zone increases and decreases exponentially with the increasing tunnel excavation length and ventilation inlet air volume,respectively.Increasing the ventilation volume can effectively minimize the ventilation blind zone.