厚砂层深桩旋挖成孔施工技术

Construction Technology of Rotary Drilling and Hole Forming for Deep Pile in Thick Sand Layer

针对旋挖钻机在全砂质地层施工时,容易产生的孔内颈缩、侧壁塌方甚至坍孔、成孔后孔底沉渣厚度偏大等质量缺陷,通过使用旋挖钻机专用高效聚合物化学泥浆代替传统的膨润土泥浆,及采用经适当改造的锥形斗齿双门双底捞砂斗替代直筒斗齿单底捞砂斗,有效地消除了使用传统泥浆和捞砂斗对施工的不利影响,极大地提高了旋挖钻机在深孔、厚砂层和富水地层的成孔效率,加快了桩基施工进度,具有良好的推广价值。

Aiming at the quality defects which are easy to occur in the construction of rotary drilling rig in whole sandy layer, such as hole necking, side wall collapse and even hole collapse, large thickness of sediment at the hole bottom after drilling, the traditional bentonite slurry is replaced with high-efficiency polymer chemical slurry for rotary drilling rig, and the straight bucket-tooth single-bottom bailing bucket is replaced with a suitably modified conical bucket-tooth double-door double-bottom bailing bucket. It effectively eliminates the adverse effects of traditional slurry and bailing bucket on the construction, greatly improves the hole forming efficiency of rotary drilling rig in deep hole, thick sand layer and water-rich layer, speeds up the construction progress of pile foundation, and has good popularization value.