SHIELD EXCAVATOR AND SEAL METHOD THEREOF

PURPOSE:To prevent the abrasion in a sliding section of a cutter seal or the incursion of earth, etc., from the sliding section by supplying hard grease to seal gaps in the front of the cutter seal, and preventing the incursion of powder of excavated earth into the seal gaps. CONSTITUTION:Hard grease over No.3 of density is injected into seal gaps 16c and 17c of the front end element in advance before the start of a shield excavator, and entrance side openings 30a and 31a are closed with plugs to start the shield excavator. After that, in the case ground in the ground improvement area is excavated, the incursion of powder of excavated earth including cement into the seal gaps 16c and 17c from the front end of the shield main body 1 is prevented. No influence is given on the drive of a cutter because of non-solidified characteristics of the hard grease. According to the constitution, even if the shield excavator excavates the ground improvement area, the solidification of cement powder or the bad influence on the drive of the cutter and heat caused by friction of a ringshaped seal section 6 with other things are prevented, and the cutter can be smoothly driven.