دانلود Importance of Controlling the Degree of Saturation in Soil Compaction

Abstract

In the typical conventional fill compaction, the dry density ρ_d and the water content w are controlled in relation to (ρd)_max and w_opt determined by laboratory compaction tests using a representative sample at a certain compaction energy level CEL. Although CEL and actual soil type affect significantly the values of (ρd)_max and w_opt, they change inevitably in a given earthwork project while CEL in the field may not match the value used in the laboratory compaction tests. Compaction control based on the stiffness of compacted soil in the field has such a drawback that the stiffness drops upon wetting more largely as the  degree  of  saturation,  S_r,  of  compacted  soil  becomes  lower  than  the  optimum  degree  of  saturation (S_r)_opt defined as S_r when (ρ_d)max is obtained for a given CEL. In comparison, the value of (S_r)_opt and the ρ_d/(ρ_d)max  vs.  S_r  -  (S_r)_opt  relation of compacted soil  are rather insensitive  to variations in  CEL and soil type, while the strength and stiffness of unsoaked and soaked compacted soil is controlled by ρ_d and “S_r at the end of compaction”. It is proposed to control not only w and ρ_d but also S_r so that S_r becomes (S_r)_opt and ρ_d becomes large enough to ensue soil properties required in design.