CONSOLIDATION PROPERTY OF ULTRA SOFT SOIL

This paper determines the consolidation characteristics and the influence of water content and load ratio on the coefficient of secondary consolidation of hydraulic fill ultra soft soil in Tianjin. A series of step-loading consolidation tests are performed on both ultra soft soil and remolded specimens using a modified oedometer with low applied stress and the ordinary oedometer. The results show that the coefficient of consolidation of the remolded specimens increases with the increasing consolidation pressure. But the ultra soft soil has aSshape of Cv-lgp curves. ThisSshape involves two parts divided by the consolidation yield stress(16kPa).The one prior to the yield stress is responsible for concave increase while the other after the yield stress is responsible for linear increase with the decreasing incrementary ratio. Unlike to the normal sedimentary remolded soils, the coefficient of secondary consolidation of hydraulic fill ultra soft soil shows a peak value as the consolidation pressure is applied. Load ratio had significant influence on the coefficient of secondary consolidation of hydraulic fill ultra soft soil. The smaller incremental load can reduce the coefficient of secondary consolidation. The coefficients of secondary consolidation of the ultra soft soil and normal sedimentary remolded soils are increased with increasing moisture content.