The invention discloses a construction method of an air shaft cast-in-situ bored
pile. The construction method comprises the following steps of (1) setting out and positioning, (2)
pile casing burying, (3) drilling
machine in-place, (4) drilling hole forming, (5) primary hole cleaning, (6) hole forming detection, (7) reinforcement cage placement, (8) guide
pipe lowering, (9) secondary hole cleaning and (10) concrete pouring and
pile casing pulling. The
water level in the hole is higher than the
water level of underground water in the drilling process; after the drilling
machine drills to the designed hole depth, a
drill bit is lifted 300-500 mm away from the bottom of the hole,
slow rotation is performed, primary hole cleaning is performed, and the time is 2-3.5 h; when pebbles or gravelswith the
diameter smaller than 10 cm exist at the bottom of the hole, a reverse circulation method is adopted for hole cleaning; and when the size of pebbles or gravels existing at the bottom of the hole is larger than 10 cm, a pumping reverse circulation method is adopted for secondary cleaning in the hole. According to the construction method, the
drill hole is effectively prevented from collapsing, and drilling tool clamping and burying and main
winch steel rope breakage are avoided.