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1 概述1.1 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(其直径比桩径大15%左右),护筒内的水位要高出自然地下水位2m以上,保持孔壁的静水压力在0.02MPa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
1 Overview 1.1 Reverse circulation drilling bored pile basic principle Reverse circulation drilling bored construction method is set at the top of the pile casing (its diameter is about 15% larger than the diameter), the water level inside the casing to be higher than the natural groundwater level 2m or more, to maintain the wall of the hydrostatic pressure at 0.02MPa above to protect the hole wall does not collapse, eliminating the need for cutting casing. Drilling rig work, the rotary disc drive drill bit at the end of cutting broken rock and soil; drilling flushing