Installation Effects on Properties of Surrounding Clays by Different Deep Mixing Methods

This paper discusses strength and modulus changes of the surrounding marine clays during and after deep mixing using three different installation methods: high-pressure jet mixing (HJM) method, powder jet mixing (PJM) method, and slurry mixing (SLM) method. Field and laboratory investigations were conducted on Ariake marine clay to evaluate these changes around columns installed by each deep mixed method (DMM). The Ariake clay is a structured clay and sensitive to disturbance. Field and laboratory test results indicate that the degrees of disturbance (DOD) to the clays around the DMM columns depend on the method of deep mixing. Among these three installation methods, HJM, PJM, and SLM had the average DOD to the surrounding sensitive clay of 41%, 21%, and 15%, respectively. The rate of strength recover during curing also depends on the method of deep mixing. The strength ratios in 30 days after deep mixing using HJM, PJM, and SLM methods ranged from 0.79 to 0.98 with an average of 0.86, 0.84 to 1.0 with an average of 0.92, and 0.9 to 1.17 with an average of 1.1, respectively. The recovery of the surrounding soil modulus was slower than that of the strength.