水利工程中的钻孔工程具有特殊的工况,采用正循环潜孔锤钻进方法在狭窄封闭的洞室内进行钻孔施工,粉尘污染严重,施工环境恶劣,影响作业工人的身体健康。为了解决施工洞室内的粉尘污染问题,在某水电站的排水孔施工中,首次应用了潜孔锤反循环钻进技术,并在上仰孔和下行孔施工试验中获得成功,有效控制和降低了洞室内的粉尘问题,有利于维护良好的施工环境。设计的A、B两种结构类型钻头主要差别是内喷孔的位置不同,A型钻头的内喷孔设计在花键上的各个平键之间,B型钻头的内喷孔则设计在花键的平键上。CFD数值模拟计算结果显示,A型钻头对环空抽吸的空气量是0.199 987 04kg/s,略大于B型钻头的0.177 524 64kg/s,说明A型钻头的抽吸能力优于B型钻头。上仰孔和下行孔的钻进试验结果表明,内喷孔设计在花键上的各个平键之间且具有双排12个内喷孔的A型钻头结构更为合理,在施工中A型钻头比B型钻头的孔口粉尘少。从反循环排渣效果看,A型钻头破碎的大部分岩粉和大颗粒岩块从中心通道排出,反循环排渣效果优于B型钻头。
The drilling tasks in hydraulic engineering were usually under severe conditions.In the narrow closed cavity, the normal DTH hammer drilling technique was generally applied to drill boreholes,but dust pollution will seriously affect the working environment and workers’health.To solve the dust pollution in the cavity,reverse circulation drilling technique with DTH air hammer was firstly applied to drill the drain holes in the cavity of a hydropower station, and the upward and downward holes were successfully drilled.The reverse drilling technique with DTH air hammer can control and reduce the dust pollution in the cavity.Furthermore,this technique can maintain good working environments.Two types of drill bits with different structures were designed for test,which were named as type A and B,respectively.The main difference between type A and B drill bits were the positions of suction nozzles.The suction nozzles of type A drill bit were evenly distributed between any two flat keys of the
