SOIL IMPROVEMENT METHOD BY BOARD DRAIN MAKING USE OF FREEZING-THAWING

摘要

PROBLEM TO BE SOLVED: To shorten a construction period, increase strength, lessen ground subsidence after execution by draining excessive water from a board drain by thawing frozen earth after freezing a soft ground and dewatering and consolidating unfrozen part.;SOLUTION: A board drain 3 is inserted in a casing 5 and driven into a ground. Then, the casing 5 is pulled out and a freezing pipe 4 is inserted into the generated hole space to pass a refrigerant therein and freeze the ground. The frozen earth is expanded by frost heave action and the unfrozed part is contracted by dewatering. Hot water is fed in the freezing pipe 4 when reaching an expected freezing range, and the freezing pipe 4 is lifted up. As the frozen earth part 1 is thawed by natural thawing or forcible thawing, the ground settles down owing to consolidation action. the frozen and thawed part has a large coefficient permeability because the structural framework is broken, and hence water is easily transferred to the board drain 3. In this way, the strength of the ground can be increased owing to highly densified ground and the residual subsidence after execution can be reduced.;COPYRIGHT: (C)2001,JPO