CONTROL METHOD OF EXCAVATION OF BOTTOM EXPANDING SECTION IN CONSTRUCTION OF BOTTOM EXPANDING SHAFT

摘要

PURPOSE:To form the shape of a bottom expanding section accurately according to a design by detecting the lowering depth and expanding width of a shell for expanding a bottom and controlling excavation while being compared with a previously programmed specified excavation pattern. CONSTITUTION:Both sidewalls of the shaft bottom section of a shaft 6 to be excavated are excavated and a bottom expanding section is formed, and concrete is placed, thus constituting a bottom expanding pile. In the method of construction, a shell 10 for expanding a bottom open-close driven by a hydraulic driving plate just above the shaft bottom section is elevated and lowered while biting in specified width to both sidewalls. The lowering depth detecting means 30 of the shell 10 and an oil gage as an expanding width detecting means are mounted at that time, and the depth and expanding width of the leading section of the shell 10 are computed automatically. A hydraulic control means and an elevation and lowering means are driven and controlled while the state is compared with a previously programmed fixed excavation pattern.