喀斯特地貌机场场平控制爆破技术实践

Practice of site leveling control blasting technology in airport with non-suspend air in karst landform area

针对贵阳龙洞堡机场三期扩建工程场平控制爆破,机场不得停航,保证飞机安全起降的要求,以工期与工程量来划分爆区,采取大规模深孔爆破为主、小规模大孔径浅孔(115 mm)爆破为辅、机械破碎相结合的方案对扩建场地进行开挖。采用逐孔起爆网路,孔内外雷管均使用双板雷管连接,孔内反向起爆,并在邻近机场围栏爆区监测爆破振动,将其控制在1 cm/s以内。选择地势较低点为起爆孔,将邻近围栏时的自由面朝向避开机场方向,爆破区域预留岩墙、覆盖炮孔,严格控制爆破飞石进入机场围栏。因为爆破区域地质环境属喀斯特地貌,又处于多降雨水地区,所以伴有溶洞且水孔率高。为此,统筹安排钻孔,改进装药方式,引入小型现场混装乳化炸药车,降低水孔率;通过测量装药高度来确定溶洞的存在,以调整炮孔布置,避开溶洞区。爆破施工方案满足了工程要求,当前单次最大起爆药量达80余吨,最大起爆炮孔数超过715个,顺利完成了不停航场平控制爆破,无爆破安全事故发生,无民爆物品流失。

As the construction site of the third-phase expansion project of Guiyang Longdongbao Airport is scheduled to go through control blasting, theairports are not allowed to suspend flights and safe take-off and landing of airplanes must be ensured. The blasting areas are divided based on project duration and work amount. A scheme that integrates large-scale deep-hole blasting, small-scale large-diameter short-hole(115 m) blasting and mechanical crushing are adopted to excavate the expansion site. A hole-by-hole initiation network is employed, and double detonators are connected inside and outside the holes wherein reverse detonation goes off. Besides, monitoring points are set in blasting areas adjacent to the airport fence to monitor blasting vibration and control it within 1 cm/s. The lower ground point is selected as the initiation hole, and the free surface near the fence is directed away from the airport, with rock walls reserved and blast holes covered in the blasting area to maximally prevent flying stones entering the airport fence. Since the blasting area is composed of a karst landform and located in a rain-laden zone, it has karst caves and a high water hole rate. Therefore, an overall plan is made for drilling,improvement made in charging methods and a small-scale on-site emulsion explosive truck introduced to diminish the water hole rate. And charge height is measured to determine the existence of karst caves so as to adjust the hole layout and avoid the cave areas. At present, the maximum single explosive capacity reaches more than 80 t, and the maximum number of blastholes exceed 715. In the fenced construction area of adjacent airports, blasting has been completed withoutany safety accident or civil blasting material lost.