Collection of pre-grouting data in the URL at the Horonobe Underground Research Laboratory Project; Data of ventilation shaft

Sawada, Sumiyuki*; Nakayama, Masashi ; Ishikawa, Makoto

The Horonobe Underground Research Laboratory (URL) Project has being pursued by the Japan Atomic Energy Agency (JAEA) to enhance the reliability of relevant investigations of the deep geological environment within the host sedimentary formations at Horonobe, northern Hokkaido. Horonobe URL will be excavated three shafts (Ventilation shaft, East shaft and West shaft) connected by three drifts (G.L -140m, G.L -250m and G.L -350m) at the time of completion. In the construction area, the sedimentary rock has spread. And the construction position is located in the stratum boundary of Koetoi formation and the Wakkanai formation. According to the investigation from the ground, existence of the fault with springwater and of the methane separated from groundwater was confirmed. From the viewpoint of the security under construction and the control of the amount of springwater from the URL, pre-grouting was carried out. This report summarizes the construction data of the pre-grouting acquired at the Ventilation Shaft.