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反循环钻成孔灌注桩基本原理反循环钻成孔施工法是在桩顶处设置护筒(护简直径应比桩径大15%左右),护筒内的水位要高出自然地下水位2 m以上,保持孔壁的静水压力在0.02 MPa以上,以保护孔壁不坍塌,省去切削套管。钻机工作时,旋转盘带动钻杆端部的钻头切削破碎岩土;钻进冲洗液(又称循环液,指水或泥浆)从钻杆与孔壁间的环状空间中流入孔底,冷却钻头,并携带岩土钻渣,混合液在负压作用下从钻杆内腔上升到地面溢进沉淀池后返回泥浆池中净化,净化后的冲洗液又返回孔内形成循环,这种钻进方法称为反循环钻进。
Reverse circulation drilling bored pile basic principle Reverse circulation drilling bored construction method is set at the top of the pile casing (nursing diameter should be about 15% larger than the diameter of the pile), the water level inside the casing to be higher than the natural groundwater level 2 m or more, to maintain the hydrostatic pressure of the hole wall above 0.02 MPa, in order to protect the hole wall does not collapse, eliminating the need for cutting casing. Drilling machine work, the rotating disc drive drill bit at the end of broken rock crushing; drilling fluid (also known as circulating fluid, referring to water or mud) from the drill pipe and the hole wall into the annular space between the bottom, cooling Bit, and carrying rock and soil drilling slag, the mixture under the action of negative pressure from the drill pipe cavity up to the ground overflow into the sedimentation tank and return to the mud pool purification, purifying the rinse and return to the hole to form a loop, the drill Into the method known as reverse circulation drilling.