A SOIL-WATER COUPLED ANALYSIS OF SAND COMPACTION WITH STATIC CAVITY EXPANSION

摘要

The mechanism and characteristics of a static compaction pile method for sandy ground are numerically investigated using a soil-water coupled computation. The compaction method is used as a measure against liquefaction, in which non-vibratory cavity expansion is gradually carried out from the bottom up. The compaction procedure of the sandy ground is simulated employing a Super/subloading Yield Surface Cam-Clay model as an elasto-plastic constitutive model for sand. By introducing the concepts of soil structure, overconsolidation and stress-induced anisotropy and their evolutions, this model allows the description of a wide variety of sand behaviors using a single set of material parameters that are independent of density. From the computational results, it is found that loose sandy ground is easily compacted/densified, because the loose soil structure of the sand is rapidly. The shear characteristics of the ground are further improved because the overconsolidation ratio of the sand is increased cumulatively when the expansion occurs above the sand element and at the unloading stages at which the casing is pulled out.