钻爆法施工隧道空气质量现场测试

为明确钻爆法施工爆破后隧道的粉尘与有害气体分布情况,检验通风、防尘效果,分别利用风速仪、粉尘仪和气体检测仪对兰渝铁路四座高瓦斯隧道的风速、粉尘和有害气体进行现场测试。测试结果显示:穿山甲风机配合螺旋式风管的压入式通风的效果最好,采用这种配置通风20 min左右,掌子面附近的粉尘、SO₂等有害气体浓度即降至允许浓度以下,通风30 min左右CO浓度降至允许浓度以下。隧道内风速主要受断面大小、掘进长度和通风设备及其维护等影响,隧道断面对净化空气所需要的通风时间影响最大,风管漏风率次之,再次为通风长度。在确保设备维护和通风管理情况下,穿山甲风机高档配合螺旋风管可实现长距离通风。

Air Quality Field Testing in Tunnel Construction with the Drilling and Blasting Method

To find out the distribution of dust and harmful gases and check the effect of ventilation and dust prevention after blasting in tunnel construction with the drilling and blasting method, the wind velocity, dust concentration and the concentration of harmful gases inside the four high gas tunnels of Lanzhou-Chongqing Railway were tested by using anemometers, dust monitor and gas detector respectively. The results of these field tests show that: there is the best ventilation effect by forced ventilation with the“Pangolin” fans and the spiral duct. After ventilating with this configuration about 20 min, the content of dust and SO₂ near the working face fell below the allowable concentration, then the content of CO dropped below the allowable concentration about 30 min of ventilation. The wind velocity inside the tunnels is mainly affected by the cross-section size, length of excavation and ventilation equipment and its maintenance. The greatest impact on the ventilating time needed to purify the tunnel air is the cross-section size and followed by the air leakage rate, then the ventilation length. So, on the condition of good equipment maintenance and ventilating management, a long distance ventilation can be achieved.