Liquefaction remediation by vertical drains with varying penetration depths

Vertical drains have been used as remediation against earthquake-induced soil liquefaction for many years. These are seen to begin fluid dissipation from deeper deposits first. Drains are not necessarily installed to the full depth of the liquefiable layer. To determine the effect of this on the efficiency of drain systems, centrifuge test results are presented. It is seen that not installing all drains through the full liquefiable depth significantly retards their performance, due to the dominance of vertical dissipation. It will be shown that a standard design chart may over-predict an improvement in drain performance.