Liquefaction potential of recent fills versus natural sands located in high-seismicity regions using shear-wave velocity

The liquefaction potential of clean and silty sands is examined on the basis of the field measurement of the shear-wave velocity, V_s. The starting point is the database of 225 case histories supporting the Andrus-Stokoe V_s-based liquefaction chart for sands, silts, and gravels. Only clean and silty sands with nonplastic fines are considered, resulting in a reduced database of 110 case histories, which are plotted separately by type of deposit. A line of constant cyclic shear strain, γ_cl ≈ 0.03%, is recommended for liquefaction evaluation of recent uncompacted clean and silty sand fills and earthquake magnitude, M_w = 7.5. The geologically recent natural silty sand sites in the Imperial Valley of southern California have significantly higher liquefaction resistance as a result of preshaking caused by the high seismic activity in the valley. A line of constant cyclic shear strain, γ_cl ≈ 0.1-0.2%, is recommended for practical use in the Imperial Valley. Additional research including revisiting available V_s-based and penetration-based databases is proposed to generalize the results of the paper and develop liquefaction charts that account more realistically for deposit type, seismic history, and geologic age.