| 摘要 |
PROBLEM TO BE SOLVED: To effectively prevent natural ground from being frozen and expanded by a freezing method. SOLUTION: When an underground cavern 14 with a large cross section is constructed, a leading tunnel (roof shield tunnel 6) is arranged around a construction area, so as to form an improved zone which surrounds the construction area, and so as to form an end section-frozen zone 10 along the cross section of the construction area in the position of the end of the constriction area. The zones 10 are formed in a multiple manner at intervals in the axial direction of the construction area, and the unfrozen natural ground is left between the zones 10. A peripheral section-frozen zone 11, which surrounds the unfrozen natural ground left between the multiple end section-frozen zones, is formed integrally with the zones 10, in the state of adhering to an outer surface of the leading tunnel. COPYRIGHT: (C)2008,JPO&INPIT |
