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25Article#ReferenceTable 2: Case studies 1-3 for reduced scale columnsDepth of pierLab scale and Significant findings, results andType of piersSoil materialinstallationapparatusobservations1Black et al.,2007bSingle and group ofthree sand verticalfrozen granularcolumnsSingle column - Ø32mm, three - Ø20mm each, H=120mm and 200 mmH/D ~ 4-10Soft KaolinClay, LL 70%,PL 36%, clayfraction 60%,σ p 200 kPa1/24-1/32 scale*Undrained soil condition: a column(if full-scalewithin the group of three performedØ0.76 m),better than the isolated columncolumns placed*Drained soil condition: the column inin chambergroup of three performed to worseØ100 mm,than the isolated single column.H=200 mm*Some effect of column buckling wasidentified.*n was found to increase fast at thebeginning of the loading, diminishwith time & eventually approach a1/15 th scale (ifconstant.2Fang andYin, 2007Single Deep CementMixing (DCM)columns composed ofordinary PortlandcementØ50 mm, H=100mm and 200 mmH/D ~ 2-4Hong KongMarine Clay,LL 51%, PL26%, G s 2.58,w% 85%full-scale Ø0.76 *Column q ult was evaluated at 1,100m), columns kPa after 30 days of curing. Columnsplaced in Q at 1,200 kPa in Hong Kong Marinechamber Ø300 Clay, i.e. effect of confining pressure.mm, H=450 mm *At the unloading, the stress imposedon the matrix soil and the column wasreduced proportionally.*Matrix soil PWP was high in earlystages of loading and dissipated fastwhen reinforced with DCM columns.3Black et al.,2007aStone quarried basaltrock columns: (1) withtabular mesh, (2) withconcrete plug withinpeat layer, (3) withinternal bridgereinforcementØ75 mm, H=720mm - tabular meshand concrete plug,H=480 mm -bridgingreinforcementH/D ~ 6-10Peat layersandwichedbetween twolayers of SandPeat: C c 5.6,density1,080kN/m 3 ,d 10 0.07, d 600.15*Q increased 50-75 % for short &150-260 % for long columns with mesh.1/8 th scale *When excavated no splitting of mesh.columns placed *The column bulging found within topin box 1.75 m 300 mm portion of the column.wide, H=2.0 m *The bridge reinforcement performedwell for Q & k o of subbase reaction.*For concrete plug k of subgradereaction found to be lower.Legend:G s – specific gravity e – void ratio Ø – diameter LL – liquid limitPL – plastic limit PI – plasticity index H – length or depth k 0 – initial stiffnessq ult – compressive strength C u – cohesion k – stiffness d 10 – effective sizew% - moisture content C c – compression index d 60 – Ø at 60% finerσ p – consolidation pressure S e – elastic settlement PWP – pore water pressure