Abstract: The soft and liquefiable soils are soil strata that are frequently encountered in the engineering projects, however, the soft soil overlying the liquefiable soil is rarely reported. Although many conventional soil improvement methods for soft soils or liquefiable soils exist, but few methods that can improve both soils combined in one site. Deep foundations are frequently used to penetrate both soils. This paper presents a case history of soil improvement method for a weak soil layer overlying liquefiable soil layer. This method has the advantage of matured technique, cost effective and fast construction. 

Key words: soft soils, liquefiable soils, ground improvement, deep mixing columns