The Field Experimental Study on Improvement of Soft Marine Clay by EK-Cementation Technique

Abstract

This study presented the results of pilot test to evaluate the applicability of EK-cementation method in field. EK-cementation method is a new method to inject specific cementation material or decompose corrosive electrode using electrokinetic (EK) phenomenon. To evaluate the effective applicability in field, various influential factors identified in laboratory test for the EK-cementation method were reflected into the field design and the following 3 conditions were employed ; electric decomposition in electrode, EK-injection and the complex method which uses both electric decomposition and EK-injection. During the pilot test in field, the cone penetration test was performed in order to evaluate the ratio of strength increase for the improved In-situ ground. The ground which has similar conditions with the one where cone penetration test was performed was selected for sampling and it was used for triaxial test, consolidation test and geoenvironmental test to analyze the origins of the shear strength increase. INTRODUCTION Existing grouting method is a traditional injection method. It injects cementation material into pore intentionally and transfers pore water into injection material. The cementation material which was injected into pore got cemented and absorbed soil particle, and thus it increased the cohesion of soil and changed it to be impermeable (Youngho Gong, 1997). During the actual injection process, fracture injection instead of permeable injection occurs and the injection material is injected inconsistently either in vein shape or in disc shape. The hydraulic Fracturing effect (cracking the ground by water pressure) caused by fracture injection leads the disturbance of ground inevitably. Although high pressure jet is used, there is a limit to apply grouting method because the injection limit of cementation material acts very sensitive towards the content of fine-grained soil. According to Karol (1990), in the case of grouting method by jet grouting, an injection was hard to perform when Silt ratio,