HYDROCHEMICAL INFLUENCE OF SHOTCRETE USED IN UNDERGROUND FACILITIES ON GROUNDWATER CHEMISTRY—PROPOSAL OF THE EVALUATION METHOD BY GEOCHEMICAL SIMULATION CODE—

Abstract

 In order to clarify the influence of shotcrete in the underground facility on the groundwater chemistry, an in-situ closed test of the mock-up tunnel was conducted at the depth of 500 m in granite. Portlandite, ettringite, gibbsite, K₂CO₃, natron, amorphous silica, calcite and brucite / nesquehonite 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 m³ of alkaline groundwater (pH 12.4) saturated with Ca(OH)₂. The estimation would improve the accuracy of prediction analysis of the long-term chemical influence of cement materials after the tunnel closure.