湖北恩施某铁路隧道定测深孔钻探施工技术

Deep hole drilling technology for final survey of a railway tunnel in Enshi， Hubei Province

摘要:

针对湖北恩施某铁路隧道定测深孔地层中存在的溶洞发育、岩体破碎严重及持续漏失等复杂地质条件，提出采用多级口径跟管扩孔钻进结合套管隔离技术，作为穿越上部溶洞地层的有效解决方案。介绍了钻具坠落（跑钻）事故的处理方法，分析了常规低固相冲洗液、炭质灰岩孔段专用冲洗液及破碎带冲洗液的应用效果，阐述了聚乙烯醇（PVA）通过吸附胶结成膜作用稳定孔壁的机理。同时，总结了导致3个钻孔报废的主要原因。为类似铁路隧道深孔钻探确立了溶洞发育区安全钻进的技术范式。

Abstract:

To address the complex geological conditions in the deep boreholes of a railway tunnel survey in Enshi， Hubei， including karst cave development， severely fractured rock masses， and persistent fluid loss， a multi-diameter casing pipe reaming drilling technique combined with casing isolation technology is proposed as an effective solution for traversing the upper karst cave formations. This paper introduces the handling method for drilling tool falling （drill string runaway） accidents， analyzes the application effectiveness of conventional low-solid-phase flushing fluid， special flushing fluid for carbonaceous limestone sections， and fractured zone flushing fluid. In addition， it elaborates on the mechanism by which the polyvinyl alcohol （PVA） stabilizes borehole walls through adsorption， cementation， and film-forming. In the meantime， the primary causes leading to the abandonment of three boreholes are summarized. This establishes a technical paradigm for safe drilling in karst development zones for similar deep-hole drilling in railway tunnels.