Rammed Aggregate Piers or Aggregate Piers (AP) elements have become an effective alternative to deep foundations or large contiguous raft foundations in soft soils. AP elements with a diameter of 600 mm are concentrated under rigid foundation elements extending through the soft or compressible soil layers. This paper will present two case histories where AP elements were utilized in soft and compressible soils to replace costly deep foundation options and permit the use of a conventional foundation systems at relatively high bearing pressures. The first case history presented in this paper details the use of AP elements at a new Fine Arts University building in Vancouver, British Columbia, where the subsurface soil conditions consisted of loose granular fills underlain by soft glaciomarine deposits. The second case history involves a new police services station in Kelowna, British Columbia, where the subsurface conditions generally consisted of several metres of fill over natural soils comprising of loose to compact sand to sandy silt over clayey silt with thin zones of sandy silt. In both of the case histories, the AP elements were load tested and results showed excellent performance, with deflection tolerance met during testing. The results confirm that AP elements are an effective alternative to deep and raft foundations.
Subjects: rammed aggregate piers, RAP, densification, ground improvement, conventional foundations, case history
Author: Roberto Avendano, B.Eng. P.Eng. and Matt J. Kokan, M.A.Sc. P.Eng.
Publisher: DFI, EFFC