The results of l8 months site observation from construction of granulated blast furnace slug(GBFS) backfilling in berth construction are reported and methods for accelerating the solidification of GBFS are discussed in accordance with the results of the series of laboratory tests for solidification of GBFS. Finally, evaluation methods for shear failure criteria parameters of solidified GBFS by using triaxial compression tests are proposed.
　From the results of the site observation, GBFS is solidifying with time. It takes a long time to solidify the whole of GBFS, because GBFS observed was not fully solidified in 18 months. It means if GBFS is used with relied on its solidification, a treatment for accelerating the solidification of GBFS is needed. For discussing this point, the condition for solidifying GBFS is checked in series of laboratory tests. They clarify that adding micro powder of furnace slag to GBFS is effective for accelerating the solidification of GBFS under sea water. Failure criteria of solidified GBFS is explained with internal friction angle and cohesion intercept. Failure criteria for residual condition of GBFS is explained by internal friction angle only. These parameters can be estimated from a single triaxial experiment.