Prediction of groundwater flow rate into shaft to the depth of 50m

Shibano, Kazunori; Orukawa, Go*; Yasue, Kenichi; Funaki, Hironori ; Kurikami, Hiroshi  

The hydrogeological model of shallow zone was built by using the data of core observation and permeability tests in the shallow boreholes drilled prior to the shaft excavation. Then, groundwater flow analysis of shaft excavation was performed using the hydrogeological model. By making a comparison between inflow rate into the shaft obtained by the analysis and measured inflow rate to the depth of 50m, the hydrogeological model and the performance of the cut-off wall established around the shaft were evaluated. The prediction analysis showed that the cut-off wall was the adequate performance and the hydraulic conductivity of fresh rock in the Koetoi Formation directly influenced the inflow rate below the cut-off wall. The simplified model in the report is efficient to reflect the excavation execution of the underground facility.