Development and Evaluation of Pile Load Test Database to Improve Driven Pile Capacity Estimates

The recommended Federal Highway Administration (FHWA) method for static pile capacity estimates is the Nordlund method developed from 25 ft long friction piles in sands. Most piles in Maine are longer than 25 ft, and many are end bearing in till and rock. The Nordlund method often gives unreliable estimates of pile capacity for piles in Maine as compared to load tests. The Canadian Foundation Engineering Manual method gives a wide range of estimates for pile capacities bearing on bedrock in Maine. Since 1990, Maine Department of Transportation (MaineDOT) has conducted dynamic pile load tests on most projects. These numerous load tests can verify which currently used static pile capacity methods offer the best estimates of pile capacity in Maine soil and bedrock conditions. The load tests give values for side shear and for end bearing. Thus estimating methods for side shear in granular and clay as well as for end bearing in tills and on bedrock can be made reliable.