GB1391662A - Method and apparatus for installing compacted sand piles in soft ground for drainage - Google Patents

Abstract

1391662 Wells &c FUDO KENSETSU CO Ltd 22 June 1972 [18 Sept 1971] 29277/72 Heading E1F In the formation of a compacted sand drain by driving casing into the ground, supplying sand to the casing, partially withdrawing the casing to form a cavity, filling the cavity with sand discharged from the casing, driving the casing to compact the sand, and repeating the operations of supplying sand, partially withdrawing the casing, filling the cavity with sand, and driving the casing to compact the sand until the drain is formed, the volumes of sand discharged into the cavity and/or the bearing strength of the sand after each compaction are or is measured and compared with design valves appropriate the depth to facilitate any necessary adjustment to design valves during subsequent operations. Two indicators are used in the formation of a drain, one giving the actual depth and the depth that the casing has to be driven to give the design volume of sand discharged at the depth, and the second giving the design bearing strength at various depths and the actual bearing strength after driving the casing. The bearing strength of the volume of sand in the drain at any depth is derived from that penetration speed of the casing or by the strain measured in the casing.