Editorial Note - Vol. 13, No. 2, 2019-Article

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The 2019 DFI Journal, Volume 13, Issue 2, presents five papers on deep foundations, including three focused on piles and two on construction in soft ground.<br /><br />One study reports predictions and full-scale testing of an instrumented precast concrete pile driven into soft marine clay. Predictions from 22 participants varied considerably, underscoring the value of high-quality testing. Residual force was also observed during a static load test conducted 210 days after driving.<br /><br />A second paper proposes a method for accounting for soil degradation under cyclic lateral loading of piles. Validated against instrumented pile tests, the method modifies standard p-y curves and applies to both rigid and flexible piles. It shows that cyclic effects diminish under mild loading and can increase sharply as pile length falls below a critical value.<br /><br />Full-scale tests of hollow bar micropiles examine uplift and lateral performance, including grout reinforced with micro steel fibers. Results show that performance depends on construction methods and drill-bit specifications. The study identifies two lateral failure mechanisms and finds that Fuller and Hoy’s method estimates ultimate uplift capacity well when plunging failure does not occur; FHWA bond-strength values for Type B micropiles may be too low.<br /><br />A case study describes seismic assessment and pile construction for a biosolids and energy recovery plant on soft, potentially liquefiable ground. A carefully executed indicator-pile program enabled shorter pile designs, saving time and cost, while highlighting the importance of collaboration among project stakeholders.<br /><br />The final paper covers jet grouting for Seattle’s Elliott Bay Seawall replacement. The project addressed seismic hazards, underground obstructions, soft soils, and restricted working space. It involved about 6,000 soil-cement columns, up to 28.3 meters deep, making it one of the largest jet-grouting projects undertaken.
Keywords
deep foundations
piles
soft ground
precast concrete pile
cyclic lateral loading
p-y curves
micropiles
uplift capacity
jet grouting
seismic assessment