Excavator for constructing underground continuous wall and construction method using the excavator

An excavator for constructing an underground continuous wall, comprising a vehicle for traveling on the ground;

• a boom horizontally extending from the vehicle and having an end outwardly projecting from one side of the vehicle;
• an endless chain cutter including an extensible vertical guide post connected to the end of the boom, a chain driving wheel at an upper end portion of the guide post, a chain sprocket at a lower end portion of the guide post, an endless chain extending around the chain driving wheel and the chain sprocket and a plurality of cutter bits and a plurality of agitator bars alternatively arranged on the endless chain;
• a jet pipe in the guide post for connecting to a fluid supply source and having a plurality of nozzles branched from the jet pipe;
• wherein each of the agitator bars comprises a base plate attached to one link of said endless chain, plural arms attached to the base plate so as to project from the base plate, and bar members fixed to free ends of the arms, respectively.