METHOD AND APPARATUS FOR RECOVERING MUD WATER IN MUD WATER-PRESSURIZING TYPE SHIELD EXCAVATION

PURPOSE:To simplify the structure of device as well as reduce the setting space of the device by a method in which excavated soil-mixed mud water is charged to a sieve to recover only mud water and then subjected to a low-speed centrifugal separator. CONSTITUTION:A mud water recoverer 20 consists of the primary treating facility 2 to remove coarse solids and the secondary treating facility 3 to remove fine particles. In the primary treating facility 2 having a sieve 4 and a decanter 21, soil-mixed mud water coming from a shield machine S is put into the sieve 4 and then supplied to the decanter 21 where fine particles are removed due to operation of 30-400G-low centrifugal forces but effective mud water material containing colloids smaller than the fine particles is left in the discharge liquid without separated. Mud water containing only effective mud water material can thus be recovered in an excess mud water tank 7 and the amount of waste mud water can be reduced.