不同送风方式对地铁隧道导洞台阶法施工锚喷作业粉尘影响
Influence of different air supply modes on dust in bolting and shotcreting operation in construction of metro tunnel pilot tunnels by bench method
摘要：
为了有效控制地铁隧道导洞台阶法施工锚喷作业时高浓度粉尘对作业人员的健康影响,本研究采用现场采样、数值模拟等方法,分析了风管安装位置、送风口到掌子面距离、风管风速对粉尘扩散的影响,研究了作业人员呼吸区粉尘浓度的动态变化,以确定最佳通风方案。结果表明:现场高浓度粉尘是由于隧道内部存在逆流现象,粉尘聚集于下台阶前侧,作业人员平均粉尘接触质量浓度超过500 mg/m3,当送风口与掌子面距离增大到20 m时,粉尘质量浓度降低150 mg/m3,若风管风速增大到15 m/s,局部降尘率达到50%以上;风管位于底拱处,风速增大至15 m/s,局部降尘率可达51.92%,可获得最佳抑尘性能;此外,现场需采取个体防护和环境净化除尘措施来减少粉尘污染。
Abstract：
In order to effectively control the influence of high concentration dust in the bolting and shotcreting operation in the construction of metro tunnel pilot tunnels by bench method on the health of operators,this study uses field sampling and numerical simulation to analyse the impact of the air duct installation position,the distance between the vent and the tunnel face,and the wind speed in the air duct on dust diffusion,and studies the dynamic changes of dust concentration in the breathing area of operators to determine the best ventilation scheme.The results show that the high concentration dust on site is due to the countercurrent phenomenon inside the tunnel,and the dust collects on the front side of the lower steps.The average dust contact mass concentration of operators exceeds 500 mg/m3.When the distance between the vent and the tunnel face increases to 20 m,the dust mass concentration is reduced by 150 mg/m3.If the wind speed in the air duct increases to 15 m/s,the local dust reduction rate reaches more than 50%.When the air duct is located at the bottom arch and the wind speed increases to 15 m/s,the local dust reduction rate can reach 51.92%,which can achieve the best dust suppression performance.In addition,individual protection and environmental purification and dust removal measures need to be taken on site to reduce dust pollution.
Keywords:metro tunnel; construction; ventilation and dust removal; dust; diffusion law; air duct position; wind speed