| 摘要 |
PROBLEM TO BE SOLVED: To provide a construction method for a tunnel capable of dispersing load caused by preceding variations in a ground and having no use for bearing the load on a preceding erection timbering. SOLUTION: A drift 16 is excavated in front of a cutting face by making it out that the drift precedes the cutting face, a steel pipe 9 is driven to a direction crossing over the direction of the tunnel excavation from the drift 16, a ground improvement material is poured into the ambient ground 7 from the steel pipe 9 to improve the ground in the ambient ground 7, an artificial ground arch 6 is constructed by the steel pipe 9 and improved ground 7, and in a construction method of a tunnel for excavating a main tunnel by making use of the artificial ground arch 6, preceding variation absorbing devices 12 and 15 absorbing preceding variations in the ground occurring in front of the cutting face with the excavation of the main tunnel are provided to the steel pipe 9, load borne by the steel pipe 9 is lightened by the preceding variation absorbing devices.
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