重探试验锤击数的杆径换算研究

Study on Rod Diameter Conversion in Hammering Numbers of DPH

摘要:

目前，国内绝大多数规范规定重探试验应采用φ42 mm钻杆，但从施工方便等因素的考虑，很多工程勘察单位趋向于采用φ50 mm的钻杆进行重探试验。通过分析重探试验要点及其影响因素，基于重探试验锤击数修正系数表，推导出杆径换算系数为0.89，并以海南省某岛礁水运工程实例加以验证。结果表明，同一地貌单元，埋深12 m以浅的珊瑚碎屑层，采用φ42 mm钻杆进行重探试验的击数与采用φ50 mm钻杆进行重探试验的击数之比值为0.875，与推导结果基本一致。

Abstract:

φ42mm rod is regulated for DPH in most standards of China, but a lot of engineering investigation units tend to use φ50mm rods based on the consideration of construction convenience factors. By the analysis on the testing points of DPH and the influencing factors, based on the revision coefficient table of DPH, the derived coefficient of rod diameter conversion is 0.89, which has been verified by a waterway engineering instance in island reefs of Hainan. The results show that for the coral clast formation of buried depth less than 12m in the same geomorphic units, the ratio of hammering numbers of DPH with φ42 drill pipe and DPH with φ50 drill pipe is 0.875, which is in close agreement with the derived results.