Umbrella body for shaft and backfill method around shaft

摘要

PROBLEM TO BE SOLVED: To improve work efficiency of backfilling when filling the space between a cylindrical structure 3 and a soil retaining wall 1 surrounding the same, after forming a shaft 4 by building the cylindrical structure 3 in an underground working space 2 excavated surrounded with the soil retaining wall 1.SOLUTION: An upper end of the cylindrical structure 3 is covered with an umbrella body 10 projecting upward, for example, a quadrangular pyramid shape. As a result, sediment for backfilling can be equally distributed by putting the sediment for backfilling on the umbrella body 10.SELECTED DRAWING: Figure 4