Liquefaction Resistance of a Colloid Silica Grouted Sand

The Chi-Chi earthquake attacked Taiwan in September 21, 1999 caused liquefaction in some alluvial deposits inland and hydraulic fills along the coastline. In the areas with obvious liquefaction, sand boils were found on the ground surface and many buildings suffered severe settlement or tilting. To prevent buildings from future liquefaction damage, subsoil underlying the settled or tilted buildings can be improved by grouting method. Considering the groutability and durability of grouting material, a colloid silica grout was chosen as a potential grouting material to improve the liquefaction resistance of in-situ sandy soil. The liquefaction resistance of this colloid silica grouted sand was studied by a cyclic triaxial test apparatus. Test results showed that up to 4 ∼ 7 folds increase in liquefaction resistance of grouted sand compared with that of ungrouted sand was observed despite the strength of this colloid silica gel was very low. Higher stress ratio and more number of loading cycles were needed to initiate liquefaction in grouted sand specimens. But a lesser liquefaction induced strain was observed. Under cyclic loading, the deformation of grouted sand specimens increased gradually with loading cycles until initial liquefaction occurred compared to a sudden increase in axial deformation of ungrouted sand specimen when initial liquefaction happened. Cyclic mobility was observed in the grouted sand specimens.