| 摘要 |
PROBLEM TO BE SOLVED: To inject a chemical solution in a wide range and reduce the number of excavation of a main pipe by providing a plurality of branch rods so as to be retractable into the main pipe and injecting a chemical solution from the front end of the branch rod into a ground. SOLUTION: An excavator is disposed at the peripheral ground of an existing structure, and a main pipe 3 is horizontally advanced into a ground bearing the existing structure. A plurality of branch rods 5 movable along a guide groove 4 in the main pipe 3 are thrusted into the ground from holes 6 formed at the outer periphery of the main pipe 3, and a chemical solution or a solidifier is injected from the front end of the branch rod 5 into the ground. The branch rods 5 are housed into the main pipe 3 and the main pipe is retracted a little and the branch rods are thrusted again into the ground. Such operations are repeated. In this way, the number of excavation of the main pipe 3 is reduced and a chemical solution or a solidifier is injected in a wide range of the ground to prevent liquefaction in the ground bearing the existing structure in an earthquake.
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