METHOD FOR DETERMINING APPROPRIATE AIR FEEDING PRESSURE TO CAISSON WORK ROOM IN PNEUMATIC CAISSON METHOD

摘要

PROBLEM TO BE SOLVED: To measure an amount of groundwater flowing into a pit and clarify a relationship between an air feeding pressure and the amount of groundwater flowing in, when the pit is drilled in a roughly vertical direction into a ground to be surveyed for reproducing a construction work state of a pneumatic caisson method, and air pressure inside the pit is raised at the same time raising a degree of saturation of the ground to be surveyed, and allowing a certain amount of groundwater to flow into the pit from the ground to be surveyed.SOLUTION: Air is sent into a casing 10 at a prescribed air feeding pressure, to fill the air inside the casing 10 to a lower edge part. Air is injected into a ground for desaturating the ground. Then, the air feeding pressure is lowered to allow groundwater to flow into the casing 10, and the air feeding pressure is measured that brings about a predetermined water level of the groundwater. At the same time, an amount of groundwater flowing into the casing 10 is measured after draining the groundwater flowing into a drainage pipe with drainage means. Thus, a relationship between the air feeding pressure and the amount of groundwater flowing in is clarified.SELECTED DRAWING: Figure 4