钻爆法隧道出渣粉尘时空扩散规律及运移计算

Spatiotemporal Diffusion Law and Transport Calculation of Slag Dust in Tunnel by Drilling and Blasting Method

为阐明钻爆法隧道出渣粉尘时空扩散规律,明确通风条件下粉尘颗粒运移计算方法,基于粉尘与呼吸性粉尘现场浓度监测数据,分析了其分布特征与规律,优化了颗粒自由沉降末速计算方法,提出了粉尘颗粒沉降速度计算公式和粒径空间分布计算方法.研究表明:时间尺度而言,出渣过程中隧道纵向不同测点粉尘浓度变化规律基本一致,衬砌台车对粉尘纵向扩散有一定阻碍作用;空间尺度而言,从掌子面至二衬台车,粉尘浓度高度分布由“上小下大”型逐渐转为“下小上大”型;不同时刻下,呼吸性粉尘占比始终大于0.6,且在远离掌子面方向显著增大,出渣过程中,呼尘占比变化不大,出渣影响较小;粉尘粒径决定颗粒消散途径,大颗粒粉尘以洞内沉降为主,小颗粒粉尘以洞外扩散为主,相比备受关注的掌子面作业区粉尘控制,通勤区与洞口附近的呼吸质量问题同样值得关注;现场监测与尘样测试结果对比表明,基于颗粒自由沉降末速优化算法的粉尘颗粒沉降速度计算公式和粒径空间分布计算方法具有较高合理性.

In order to clarify the spatio-temporal diffusion law of slag dust in the drilling-blasting tunnel,and to clarify the calculation method of dust particle migration under ventilation conditions,based on the field concentration monitoring data of dust and respiratory dust,the distribution characteristics and laws are analyzed,and the calculation method of the final velocity of particle free settlement is optimized.The calculation formula of dust particle settlement velocity and the calculation method of spatial distribution of particle size are proposed.The results show that:In terms of time scale,the variation law of dust concentration at different measuring points in the longitudinal direction of the tunnel during slag discharge is basically the same,and the lining trolley has a certain inhibitory effect on the longitudinal diffusion of dust.In terms of spatial scale,from the working face to the secondary lining trolley,the height distribution of dust concentration gradually changes from the type of‘upper small and lower large’to the type of‘lower small and upper large’.At different times,the proportion of respirable dust was always greater than 0.6,and increased significantly away from the tunnel face.During slag discharge,the proportion of exhaled dust changed little and the effect of slag discharge was small.The dust particle size determines the particle dissipation pathway.The large particle dust is dominated by the settlement in the tunnel,and the small particle dust is dominated by the diffusion outside the tunnel.Compared with the dust control in the working area of the working face,the air quality problems in the commuting area and near the tunnel entrance are also worthy of attention.The comparison with the field monitoring and dust sample test results shows that the calculation formula of dust particle settling velocity and the calculation method of particle size spatial distribution based on the particle free settling final velocity optimization algorithm are highly reasonable.