PURPOSE: To constitute the shape of a tunnel after branching in a circular and other free shapes by housing two shield excavators into a cocoon type shell body and branching and starting the shield excavators while giving reaction to the shell body at a branch point.
CONSTITUTION: In a shell body 1, into which two shield excavators 2 are housed, two cylindrical bodies having circular cross sections are connected and the cross sections are formed in a cocoon shape, and a plurality of shell body jacks 11 are arranged around the inside of the shell body 1. The shield excavator 2 having approximately the same external shape as the inside diameter of a short cylindrical body is received in the short cylindrical body 1A having a circular cross section, and the shield excavator 2 having an outside diameter smaller than the inside diameter of a long cylindrical body is housed into the long cylindrical body 1B having a notch circular cross section. When the two shield excavators 2 are disposed in parallel and excavation is conducted, both shield excavators 2 and the shell body 1 are forward moved integrally, and segments are given reaction by the shell body jacks 11 and advanced. When the excavators are branched the shield excavators 2 on the insides are stated from each cylindrical body, and each segment is assembled in the shell body 1.
BESSHO TOSHIHIKO
ITO HIROYUKI
UEHARA TOSHIAKI
ISHIKAWAJIMA HARIMA HEAVY IND