Application construction method null of the plug of the shaft lower part in the underground

摘要

PURPOSE:To prevent the leakage of gas and water by a method in which water- tight concrete is placed around a casing, and grout is injected into the space between the rockbed and the concrete through a grouting pipe after the concrete hardens to form a plug. CONSTITUTION:A ringed casing support 3 of reinforced concrete is constructed near the lower part of the vertical pit 2 of underground storage tank 1. A lowest metal casing 4 with an upper end flange 4a is set on the support 3. A short metal casing 5 is then welded to the upper end of the casing 4 and a grouting pipe 6 is attached to the periphery of the casing 5. Water-tight concrete 7 is placed around the casing 5 and hardened. Afterwards, a grout is injected into the space between the rockbed and the concrete 7 through the pipe 6. A casing 8 is additionally connected to the upper end of the casing 5 and water-tight concrete 9 is placed between the casing 8 and the rockbed to form the whole of a vertical pit 2.