A STUDY ON PENETRATION BEHAVIOR TO ROCK FRACTURES OF CEMENT GROUT BY FIELD TEST

Abstract

Field cement grouting test for rock fractures was conducted to validate the laboratory test results. Through the observation of core samples, inside wall of injection hole and enlarged core samples including injection hole, following results were obtained. (1) Cavities and vortices were found in injection holes, and the clogging at the entrance of fracture was also observed. (2) Cement grout could improve only narrow areas at a fracture width of 0.3 mm or smaller, so cement grouting was not done efficiently. (3) Grout penetrated deeper into originally greater fractures. (4) Using highly dense grout mix (watercement ratio of 1:2) as a starter mix was found not to cause problem and would reduce the injection time under certain injection pressure or at a certain fracture width.