A New Method of Reducing Liquefaction Susceptibility through Pore Water Modification

Soil liquefaction during earthquakes causes major destruction. Liquefaction occurs when pore pressures increase to the point where the soil effective stress is very low, reducing soil strength to the point where existing loads cannot be supported. Reducing susceptibility to liquefaction has traditionally been done by grouting, drains or densification. A new method of reducing liquefaction susceptibility is presented: immobilizing pore water. A gel-like chemical is added to saturated soil. The resulting material is not conventional soil", and does not liquefy in the conventional sense. Excess pore pressures are still generated, but effective stress is not reduced according to the classical equation. The result is that the soil retains a considerable amount of strength. This paper gives preliminary results of cyclic triaxial tests on clean Ottawa density sand impregnated with gel. A procedure for preparing very loose triaxial specimens by freezing is reviewed. The results indicate liquefaction susceptibility is significantly reduced.