A study of an instrumented silo foundation, constructed in 1996, was undertaken. The foundation was composed of a doughnut shaped raft supported by 20 piles, which were embedded over the entire length in plastic clay having a high water table. The clay extended to a depth of more than 200 meters. The constructed pile length was 21 to 22 m, with a diameter of 1.1 m. Ten of the piles were instrumented with strain gages, spaced at depths of 2 m, 10 m, and 20 m. The raft was based on a well compacted granular soil (kurkar). The head of the piles penetrated approximately 200 mm into the raft, unconnected, in order to enable independent vertical uplift movements. Four pressure cells were placed between the raft and the compacted granular fill. Measurement points for the vertical relative movement between the instrumented pile heads and the raft, as well as elevation points for monitoring the vertical movements of the silo wall, were placed at 8 locations, symmetrically arranged. Systematic measurements for the last 8 years, since the first filling of the silo, were performed. The applications of live loads were recorded on a daily basis and were processed numerically computerized and as diagrams. Early computations for the prediction of load distribution between the raft and the piles were performed by several methods. Observations based on measured data showed large discrepancies during the first 2 years. In the last 6 years, load distribution between the raft and the piles and load transfer along the piles showed steady trends and approached the early predictions.
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