NCHRP Research Report 1112: Design of Piles for Downdrag, Database of Instrumented Static Load Test Data on Driven Piles

Downdrag and dragload develop when soil moves downward relative to the foundation element (as with consolidating clays or seismically induced liquefaction) and can result in excessive/destructive pile settlements. The magnitude of downdrag and dragload is fundamentally a function of the load transfer between the pile and the soil. A database of 68 static load tests on strain gauge instrumented piles, which were obtained from documented literature, was developed to investigate load transfer during dragload events. The load transfer from these instrumented piles to the surrounding soil, including side (t-z) and toe bearing (q-z) resistance, was developed from the reported pile head load-displacement and pile load distribution. The pile database includes the following types of piles: steel pipe, steel H, concrete filled steel pipe, concrete square, concrete cylinder, and concrete H-piles. The residual load for each pile was estimated to correct for the influence of residual load on the developed side and toe bearing resistance of each pile.

The database includes the pile load-displacement and pile load distribution during static load testing for each pile, load-transfer response for each strain gauge depth on each pile, estimated residual load distribution for each pile, residual load corrected load-transfer response for each strain gauge depth for each pile, discretized standard penetration test (SPT) and/or cone penetration test (CPT) of soils when available in the literature, and general pile and site information for each pile.