Studies on grouting performance in Mizunami Underground Research Laboratory (Contract research)

Kawamura, Hideki*; Ando, Kenichi*; Noda, Masaru*; Tanaka, Tatsuya*; Matsuda, Takeshi*; Fujii, Haruhiko*; Hashimoto, Shuji*; Ueda, Tadashi*; Matsui, Hiroya; Takeuchi, Shinji; et al.

JAEA-Technology 2009-081, 182 Pages, 2010/03

JAEA-Technology-2009-081.pdf:28.89MB

Grouting has practical importance for the reduction of groundwater inflow into excavations during construction of underground facilities. Considering the performance assessment of a radioactive waste repository, the performance of the engineered barrier system could be adversely affected by a high pH plume generated from grout. Therefore, a quantitative estimation of the effectiveness of grouting and grout material is essential. This study has been performed in the Mizunami URL being excavated in crystalline rock as a part of the Project for Grouting Technology Development for the Radioactive Waste Repository funded by METI, Japan. The aims were to evaluate the applicability of existing grouting technology and to develop methodology to determine the distribution of grout and change in hydraulic properties of the grouted rock volume. The target rock is the volume of rock around a planned refuge niche where the pre-excavation grouting was performed at 200-m depth from ground surface. After excavation of the refuge niche, ten boreholes were drilled and different kinds of investigations were carried out during and after drilling. The results were integrated and groundwater flow analysis of pre and post excavation grouting conditions were carried out to estimate quantitatively the effect of pre-excavation grouting. The results suggest that current pre-excavation grouting technology is effective for reduction of groundwater inflow into excavations and that hydraulic conductivity of the surrounding rock can be reduced by more than one order of magnitude.

Study on grouting performance in the Mizunami Underground Research Laboratory; Modification and application of hydraulic test for grouting

Ando, Kenichi*; Takeuchi, Shinji; Matsui, Hiroya; Tanaka, Tatsuya*; Hashimoto, Shuji*; Fujii, Haruhiko*

Dai-38-Kai Gamban Rikigaku Ni Kansuru Shimpojiumu Koen Rombunshu (CD-ROM), p.137 - 142, 2009/01

Evaluation of the effect of grouting on the geological environment is important for quality control of the design and management of the construction of underground facilities for high level radioactive waste disposal. Lugeon test has been commonly used to check the hydraulic characteristics around borehole whether or not to inject grout in Japan. The aim of this study is to develop a hydraulic test which can be applied to obtain hydraulic conductivities of low permeable rockmass (e.g. 10 to 10m/s) during grouting. The proposed hydraulic test with the test sequence of water injection and pressure recovery has been carried out in Mizunami URL excavated in crystalline rock. The developed type curve matching methodologies have been applied to evaluate hydraulic conductivity in-situ in a simple manner. Lessons learned for future application for grouting have been addressed.