Comparison of Settlement Predictions for Single Piles in Sand Based on Penetration Test Results

The analysis of settlement for driven piles in cohesionless soils is a complex soil structure interaction problem. The total settlement for such a pile is generally considered to be the sum of the following three components (Vesic 1977): 1. Settlement due to axial deformation of the pile shaft 2. Settlement of the pile point caused by load transmitted at the pile tip 3. Settlement of the pile point caused by load transmitted along the pile shaft. A recent pile load test program was conducted to assist in the design of the foundation for a new bridge over the Cimarron River in northwest Oklahoma. The load tests were conducted on a 0.66 m closed-end steel pipe pile and a 0.61 m octagonal prestressed concrete pile. Prior to and following the pile load tests, a number of in situ penetration tests were conducted at the site. They included: Standard Penetration Test (SPT), mechanical cone penetration test (MCPT) and electric cone penetration tests (ECPT). This study compares the total settlement and components of settlement measured during the pile load test on the two types of pile with that estimated by the various penetration test results. The Coyle method of analysis was used for the SPT data, and the Verbrugee method was used for the mechanical and electric cone data. This study reports the details of the site investigation and in situ penetration tests, the comparisons between predicted settlements and pile load test results, and documentation of a case study of the use of pile load tests to design bridge foundations.