Sealability Recovery of Fractured Rocks by Post-failure Consolidation

Post-failure consolidation was carried out on Kimachi sandstone, Toyotomi siliceous mudstone and Inada granite to clarify whether the increased hydraulic conductivity due to failure decreased by post-failure consolidation or not. The hydraulic conductivity of post-failure consolidated rocks were 0.3–0.6 times that before post-failure consolidation and 0.9–1.5 times that before failure for Kimachi sandstone and the ratios were 0.4 times and 0.6 times for Toyotomi siliceous mudstone. On the other hand, the ratio was 0.2 times and 16 times for Inada granite. Namely, the phenomenon in which the increased hydraulic conductivity decreases by post-failure consolidation was obviously confirmed for the clastic rocks and was confirmed at some degree for the crystalline rock. The dominating mechanisms of decrease in hydraulic conductivity due to the post-failure consolidations were considered to be closure of rupture plane by crushing of mineral particles and irrecoverable closure of microcracks and elliptic pores in intact rock matrix due to plastic deformation for Kimachi sandstone, time-dependent closure of rupture plane due to visco-plastic deformation and visco-plastic pore collapse in intact rock matrix for Toyotomi siliceous mudstone, and a little visco-plastic deformation and a few pressure solution at the rupture plane for Inada granite. The different mechanisms were mainly induced by the differences in strength and deformation characteristics of mineral particles and rock matrixes.