Abstract: A method for producing a resin sintered body 1 by applying an ink 3 to thermoplastic resin powder 2 and sintering the powder, the method including the step of immersing an intermediate resin sintered body 1m, which has an unevenly colored region on the surface thereof and the whole of which has been already sintered, in a surface treatment liquid containing sulfuric acid and chromic anhydride, in which the concentration of chromic anhydride is 300 g/L or more, for 5 minutes or longer. When producing a resin sintered body by sintering thermoplastic resin powder, the surface of the resin sintered body can be evenly and sufficiently colored to an extent required without an unevenly colored region on the surface thereof, and also the surface of the resin sintered body can have a good appearance and smoothness.

Abstract: A tunnel boring machine for collecting earth excavated upon rotation of a cutter disk includes a non-pressurized chamber behind the cutter disk for collecting earth excavated by the cutter disk and discharging the earth with a carrying fluid. The machine includes a first open tank arranged in the non-pressurized chamber which serves as a vessel for containing the carrying fluid as well as a hopper for collecting excavated earth. Carrying fluid supply apparatus is provided for supplying the carrying fluid to the first open tank and suction/discharge apparatus is provided for sucking and discharging the carrying fluid supply to the first open tank rearwardly together with the collected earth. Water level control apparatus provided for monitoring a water level of a carrying fluid in the first open tank and keeping the water level between a minimum water level and a maximum water level.