| 摘要 |
In order to form an air-mixed zone containing tiny air bubbles in the ground with feeble cohesion or the cohesionless ground, an air-tight cover 1 covering the air-mixed zone is placed on the ground surface, along the outside periphery of the cover 1 an air-tight cut-off wall 2 extending down to the depth of ground water table is installed, the pipes 4 for blowing air are pushed from the ground surface penetrating through the air-tight cover 1 down into the ground, by blowing compressed air from the tip portion of the pipes 4 and collect the blown air through the pipes 5 for collecting air which are spaced at suitable distance from the pipes for blowing air and pushed into the ground in a simultaneous cycle of work with the pipes 4 for blowing air in repeated cycles so that the blown in air circulates and spreads uniformly in the air-mixed zone and splits into tiny air bubbles. The tiny air bubbles stay in the air-mixed zone semipermanently and the degree of saturation of ground water in there is kept at such a low level that any liquefaction due to violent earthquake does not occur even many dozens of years or several centuries after the air-mixed zone is formed by the above-mentioned method which does not induce any such undesirable defect as land subsidence.
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