2.5.2 Pile group
The ultimate bearing capacity of DCM column groups depends on both the shear strength of the untreated soil between the columns and the shear strength of the column material. Failure is either governed either by the bearing capacity of the whole block with DCM columns (Fig. 2.22a) or by local bearing capacity of the block along the edge (Fig. 2.22b) when the spacing of the DCM column is large. In certain cases, shear resistance along a failure surface which cuts through a whole block may govern by the shear strength of the surrounding soft clay, cu. The ultimate bearing capacity of column group for block failure is given as: