硬质岩滑坡深大抗滑桩一体化旋挖成孔技术及应用

Integrated rotary drilling and hole forming technology and application for deep and large anti-slide piles with hard rock

摘要:

硬质岩深大抗滑桩桩孔成孔效率是滑坡灾害防治的难点问题之一。选取川西南典型复杂山区硬质岩滑坡抗滑桩成孔为研究对象，系统分析了裂隙弱发育深部硬质玄武岩地层抗滑桩传统工艺成孔存在的问题，对此设计了9种组合旋挖成孔工艺方案进行现场试桩试验，从钻进效率、技术及经济可行性等方面进行了分析论证。现场试验及分析结果表明：采用“大扭矩截齿筒钻旋挖+扩孔直径差0.4 m”分级扩孔一体化成孔技术在硬质岩地层中钻进效率较高、钻具损耗较低、成本较低，验证了硬质岩抗滑桩高效旋挖分级扩孔技术的可行性和高效性，对比现有人工成孔、冲击钻成孔、旋挖一次成孔等工艺，从安全、效率、成本等方面均得到了极大提升。该技术成功应用于白鹤滩迁建集镇后缘滑坡桩基施工，每延米综合耗时1.43 h，较改进前旋挖一次成孔效率提升3倍，成本降低了60%。该技术为复杂地质条件下水敏型、震敏型硬质岩滑坡抗滑桩快速成孔施工提供了高效、可行的技术方案。

Abstract:

The efficiency of pile hole formation for deep and large anti-slide piles in hard rock has always been a highly concerning issue in the industry. This study selected the formation of anti-slide pile holes in typical complex mountainous areas with hard rock landslides in southwestern Sichuan as the research subject. It systematically analyzed the traditional drilling pain points in deep hard basalt formations with weakly developed fractures， and designed nine combined rotary drilling hole formation process schemes for on-site pile testing. An analysis and demonstration were conducted from the aspects of drilling efficiency， technical and economic feasibility. The on-site testing and analysis results showed that the integrated hole formation technology of “large torque cutting tooth barrel drilling rotary drilling and stepwise borehole expansion with optimal cutting diameter difference of 0.4m” has the highest drilling efficiency， lowest tool wear， and lowest cost in hard rock formations. It verified the feasibility and efficiency of the high-efficiency rotary drilling stepwise borehole expansion technology for anti-slide piles in hard rock formations. Compared with existing manual hole formation， impact drilling， and one-time rotary drilling， this technology has greatly improved safety， efficiency， and cost. The technology has been successfully applied to the construction of pile foundations for landslides at the rear edge of the relocated Baihetan Town， with an average time consumption of 1.6 hours per meter， which is three times more efficient and 60% percent less costly than the previous improved one-time rotary drilling efficiency. This technology provides an efficient and feasible construction technical solution for the rapid hole formation of water-sensitive and earthquake-sensitive hard rock landslide anti-slide piles under complex geological conditions.