| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent contamination of soil, underground water, lake water, river water, seawater, or the like due to spouting of an excavation fluid at a reduced part of earth covering of an underground hole or due to dissipation of the excavation fluid in an area where an unstable stratum exists around the underground hole, in excavating the underground hole using the excavation fluid. Ž<P>SOLUTION: In excavating the underground hole 10 using the excavation fluid, bore holes 41, 42 for extracting the excavation fluid are provided beforehand in an area with a risk of the excavation fluid dissipating in the ground 20 around the underground hole 10 or in a region with a risk of the excavation fluid spouting to the ground surface 21, and the underground hole 10 is excavated to communicate with the bore holes 41, 42. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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