Vacuum consolidation of soft clay via vertical drains and associated design charts
A system of vertical drains combined with vacuum preloading is an effective method for promoting radial flow to accelerate soil consolidation. An analytical solution using the lateral soil permeability and compressibility is introduced by considering the decrease in permeability within smear zone. Vacuum pressure is incorporated as negative pressure (suction) distributed along the drain length and across the soil surface. Numerical analysis using the proposed equivalent plane strain solution is employed to predict the excess pore pressures, lateral and vertical displacements for a selected case history at the site of the Sunshine Motorway, Queensland. Design charts and examples are also presented for practical convenience.