Hydrochemical influence of shotcrete used in underground facilities on groundwater chemistry; Proposal of the evaluation method by geochemical simulation code

Iwatsuki, Teruki  ; Shibata, Masahito*; Murakami, Hiroaki  ; Watanabe, Yusuke  ; Fukuda, Kenji

In order to clarify the influence of shotcrete in the underground facility on the groundwater chemistry, an in-situ closed test was conducted in the mock-up tunnel at the depth of 500 m. Brucite, Ettringite, Ca(OH) , Gibbsite, KCO, NaCO 10HO, SiO (a) and Calcite were identified as the dominant minerals affecting the water chemistry. Furthermore, the shotcrete constructed in the tunnel has a reaction capacity which can produce about 570 m of alkaline groundwater (pH12.4) saturated with Ca(OH). The estimation would improve the accuracy of prediction analysis of the long-term chemical influence of cement materials after the closure of the tunnel.