| 摘要 |
PROBLEM TO BE SOLVED: To provide a water flow section forming method for an underground impervious wall capable of reliably forming a water flow section of a required size at a required position without requiring a large-scale execution machine. SOLUTION: A double-structure core material inserted with an inner pipe 8 having a bit 11 at the tip into an outer pipe 10 and protruded with the tip of the inner pipe 8 from the tip of the outer pipe 10 by the prescribed length is used as part or all of the core material of an underground wall 2 serving as an impervious/retaining wall made of soil cement. After the construction of an underground structure is completed, the inner pipe 8 is pulled up while being axially rotated or vertically reciprocated, and part of the underground wall 2 is crushed by the bit 11 to form a water flow section 12 in which underground water can pass. When the inner pipe 8 is pulled up, a water permeable material 6 such as crushed stones filled in the inner pipe 8 in advance is left to secure the water permeability of the water flow section 2.
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