| 摘要 |
PROBLEM TO BE SOLVED: To provide an improvement area formation method for forming a polygonal checker arrangement (diagonal arrangement) improvement area such as a quadrangular columnar improvement area, a triangular columnar improvement area, also a quadrangular checker arrangement (diagonal arrangement) improvement area and a triangular checker arrangement (diagonal arrangement) improvement area.SOLUTION: A method for injecting liquid including a hardener liquid under high pressure from an injection nozzle provided in the rod tip part peripheral direction by inserting a rod into the ground, is the improvement area formation method for establishing the quadrangular columnar improvement area K2 in which the length of respective one sides of a quadrangle is L1 and the improvement length (a height) is L2, and an underground arrival distance L3 of the hardener liquid injected under the high pressure from the injection nozzle satisfies L3≥(L1)/2, and after inserting a rod into the predetermined depth in a corner part of the quadrangular columnar improvement area K2, while injecting the hardener liquid under the high pressure from the nozzle, the rod is extracted by the length of L2 while repeating substantially 90-degree rocking or substantially 90-degree vertical motion rocking (wave type rocking) or substantially 90-degree oblique rocking (lightening type rocking) in the predetermined direction by the predetermined number of times, so that the quadrangular columnar improvement area K2 is formed. |
