水炮泥降尘施工隧道粉尘粒度分布演化的非稳态分析

Unsteady analysis of dust particle size evolution in construction tunnel based on water stemming

分别以氯化钾(KCl)基水炮泥和氯化钠(NaCl)基水炮泥为堵料对隧道炮孔进行封堵后爆破,采用相关仪器对掌子面爆破后施工作业区内粉尘颗粒及浓度值进行现场采集,通过图像处理软件对2段试验中粉尘分散度及外形参数进行分析。研究结果表明:不同基料降尘剂对炮眼封堵爆破后,相同周期通风时间条件下呼吸性粉尘与总粉尘浓度演化趋势基本一致,但粉尘粒度分布出现明显差异,粉尘颗粒长径比参数均在1附近发生窄幅震荡;各粒径粉尘颗粒频率分布基本符合正态分布,呼吸性粉尘粒径分布峰值范围在5~7μm之间;以氯化钠(NaCl)作为降尘剂基料时小粒径粉尘的降尘效果优于氯化钾(KCl)基降尘剂,掌子面爆破通风60 min后氯化钠(NaCl)基降尘剂条件下呼吸性粉尘与粒径小于2μm的肺泡区高沉积呼吸性粉尘的平均累计分布较氯化钾(KCl)基降尘剂条件下分别下降38.68%和69.65%;隧道粉尘净化效果进行判断时除考虑呼吸性粉尘与总粉尘浓度下降率外,还要将粉尘粒度的分布变化情况纳入判断依据。

KCl-based stemming and NaCl-based stemming were respectively used as the blasthole plugging materials to seal and blast in construction tunnel,dust particle and concentration was collected using related instrument in construction site after working face blasting,meanwhile the dispersity and shape parameter of dust were analyzed by image processing software.The results indicate that the concentration of total dust and respirable dust have evolved in a similar way when the ventilation time was same,however there were significant differences in dust particle size distribution after blasting under different dustfall agents.The draw ratio of dust particle were distributed at around 1 during the experiments.The frequency distribution of dust fitted the normal distribution basically,and the peak of respirable dust range 5μm to 7μm.When NaCl is used as the base material of dustfall agent,the effect of small-particle dust remover is better than that of KCl-based dust agent,the average cumulative distribution of respirable dust and dust with particle size less than 2μm were decreased 38.68%and 69.65%,respectively,compared with that of KCl-based dust agent after blasting and ventilation for 60 min.In addition to concentration of total dust and respirable dust,the distribution and change of dust particle should also be taken into account when judging the purification effect of tunnel dust.