反井钻开挖大倾角斜井导孔的工程实践

针对柳洪水电站压力管道下斜段洞身长、倾角陡、工期紧、地质条件复杂、安全隐患突出等问题,开挖中采用反井钻开挖斜井导孔与人工开挖斜井导洞对接技术,安全隐患少,施工效率高。介绍了反井钻开挖大倾角斜井导孔的施工程序、操作步骤和导孔纠偏措施。在反井钻施工中通过调整主副泵工作压力、转速,合理调整稳定钻杆分布等措施控制孔斜,取得了反井钻实际钻孔129 m、平均日进尺7.5 m、导孔钻头落在距斜井中轴线下方1.8 m处的良好效果,成功与人工开挖导洞对接。

Practice of using raise boring in excavation of guide hole for shaft with large angle of inclination

In consideration of some problems in second inclined section of the pressure conduit project at Liuhong Hydropower Station,such as long distance to be excavated,large angle of inclination,short construction period,complicated geological condition,and some hidden dangers,a construction scheme,i.e.excavation of the guide hole for the inclined shaft with raise boring and connection of the guide hole with another hole excavated manually,was adopted.The technique overcomes some hidden dangers and has high efficiency in construction.In this paper,the type selection for raise boring,steps for guide hole excavation,and measures for deviation rectification were introduced.By regulation of the working pressure and rotational speed of main pump and sub-pump,reasonable allocation of boring rods,and adoption of reasonable deviation rectification measures to control the angle of inclination,a satisfactory result with the length of excavation being 129?m,the daily mean excavation being 7.5m and the drill bit being located at 1.8m under the axis of inclined shaft was obtained,and the excavated guide hole was successfully connected with the manually excavated one.