| 摘要 |
<p>PROBLEM TO BE SOLVED: To realize a long and precise drilling of the ground without any lubricant or slurry by a small and light drilling machine. SOLUTION: In this drilling method of the ground, a first large diameter auger 801 is used to push in the first large diameter casing 5 while excavating the ground 10. When the excavating efficiency of the auger 801 has decreased, the auger is pulled out, in the first drilling process. The second middle diameter casing 6 having a smaller outer diameter than the inner diameter of the first large diameter auger 801 and the second middle diameter auger 802 having a smaller outer diameter than the inner diameter of the second middle diameter casing 6 are used in the second drilling process, against the drilling part of the first drilling process. Subsequently, the third, the fourth,... casings and augers are used likewise until the drilling is completed in the third, the fourth... processes.</p> |
