Effect of distribution patterns of DSM columns on the efficiency of liquefaction mitigation

Abstract

Liquefaction during earthquakes can result in severe damage to structures, primarily from excess pore water pressure generation and subsoil softening. Deep Soil Mixing (DSM) is a common method of soil improvement and is also used to reduce shear stress in liquefiable soils to control liquefaction. The current study evaluated the effect of DSM columns and the implementation of different column patterns on controlling liquefaction and decreasing settlement of shallow foundations. A series of shaking table physical modeling tests were conducted for three different distribution patterns of DSM columns (i.e., square, triangular, and single) with a treatment area ratio of 30%. The treatment was applied to a liquefiable soil under a shallow model foundation. The results showed that the excess pore water pressure decreased by 20% to 50% in comparison with the unimproved soil, depending on the DSM column pattern used. For improved soil, the shallow foundation settlement was about 10% more than that of the unimproved soil in the best case. Increase in soil shear stiffness after the use of the DSM columns was compared with the results of existing practical relations to increase soil shear strength.