While digging the tunnel in the spring water Characteristic natural ground,

摘要

PROBLEM TO BE SOLVED: To easily estimate the quantity of spring water and a permeability coefficient of the natural ground in excavating a tunnel and to perform optimum cut-off improvement based on them.;SOLUTION: The tunnel (a pilot pit 101) is excavated by a closed type tunnel advancing machine 102, and at the same time, spring water ejecting from cavities around is drained to lower the water level in the cavities by a fixed quantity. Time required for it and the drainage quantity are measured, and time required to recover the water level after the stop of drainage is measured. On the basis of the measured values, the spring water quantity and permeability coefficient per unit time are estimated. The above estimation is performed when excavating the pilot pit, and cut-off improvement on the water springing natural ground outside the pilot pit is performed based on the estimation.;COPYRIGHT: (C)2005,JPO&NCIPI