Abstract: The soft soils improved by the cement agents have received different results due to the significant variation of the components and sedimentary environments of soft soils in different regions. This paper presents the field test results of soft soil mixed with different content of cement for the utility tunnel construction project in a coastal city. The performance of the utility tunnel in soft soils before and after the improvement was also analyzed by using finite element method. The test results indicate that the wet mixing method is more appropriate to apply the cement in the onsite soft soil strata. The compressive strength of cement mixed soil increases with the cement contents. The most costeffective cement content is 25%. The numerical analysis results indicate that the utility tunnel would have a tension failure potential and the performance of the utility tunnel after the soil improvement is satisfactory.

Key words: Cement Mixed Soils, Compressive Strength, Utility Tunnels, Mucky Soil Improvements