Statistical Analysis for Strength Variation of Deep Mixing Columns in Singapore

Deep Mixing is widely used in Singapore and other countries all over the world. Due to the non-uniformity of the mixing, the strength of the deep-mixing improved soil is often highly variable and this has been a problem in practice. Two projects in Singapore using DM in ground treatment for Marina Bay Financial Centre (MBFC) and new Nicoll Highway MRT Station (NCHS) are introduced and statistical analysis is performed to study on the variation of the unconfined compressive strength of the deep mixing column samples from these projects. The results indicate that the sample COVs lie in the range suggested in previous literatures. With enough statistical sample size, samples from the same operating parameters show similar trend in their histograms. Moreover, the geological conditions and operating parameters considerably affect the mixing quality. The data show that the design unconfined compressive strength of the deep mixing columns is conservative.