PURPOSE: To naturally collapse a block and to prevent the burying of a dam and the lowering of a river bed at a downstream by using a deposited sand collected at the upstream as an aggregate, adding a binder, cement, admixture, etc., to the aggregate to obtain the block easy to collapse and arranging the block on the downstream side of the dam.
CONSTITUTION: A deposited sand collected on the upstream side of a dam is used as an aggregate, the aggregate is mixed with a binder (e. g. converter slag), cement and an admixture (e. g. methylcellulose) or mixed with cement and a crushing material (e. g. sodium sulfate) to form a concrete block easy to collapse. The concrete block is arranged at a place on the downstream side where the water current is easily collided. Water is infiltrated into the block to gradually and naturally collapse the block into sand which is allowed to flow toward the downstream side.
OWAKI EIJI
MARUYA TAKESHI
MATSUOKA YASUNORI
