Graduation Year
2024
Document Type
Thesis
Degree
M.S.C.E.
Degree Name
MS in Civil Engineering (M.S.C.E.)
Degree Granting Department
Civil and Environmental Engineering
Major Professor
A. Gray Mullins, Ph.D.
Committee Member
Michael J. Stokes, Ph.D.
Committee Member
Zachary B. Haber, Ph.D.
Keywords
Database, Dilation, Gephi, Resistance, Restrike
Abstract
Prestressed concrete piles (PCP) are a common geotechnical foundational element employed in marine and land bridges. PCP are commonly driven by an impact diesel hammer until the desired nominal bearing resistance is reached at the end of the initial drive (EOID). At a later time, the pile resistance may be verified, but not always, via a restrike, usually with the same impact hammer. At the beginning of a restrike, the resistance of the pile is rarely equal to the resistance at the EOID either increasing, known as set-up, or decreasing, known as relaxation. Set-up is clearly beneficial, however, this thesis covers relaxation and the mechanisms that cause it. A large enough loss of resistance of a pile or group of piles can be detrimental to the structural capacity if preemptive measures are not realized.
The driving records of 23 FDOT bridges, both marine and land, have been considered. The records contain information including boring logs, driving logs, and pile information sheets of each pile of each pier of each bridge. Specific variables from these records were extracted into an EXCEL(TM) database for analysis in various software. The available literature indicates that relaxation occurs most commonly in medium to very dense, saturated sandy soils but also occurs less frequently in other soils such as inorganic silt, limestone, and shale, with several exceptions to consider.
This exploratory thesis covers phase 1 of a 2-phase project. This phase discusses the history and accepted mechanisms of relaxation to determine which variables to extract from the driving records for analysis. The extracted variables are then analyzed to determine correlations that agree with the existing mechanisms of relaxation and present new correlations.
Scholar Commons Citation
Knowles, Dalton E., "An Analysis of Driven Pile Relaxation in Florida Soils" (2024). USF Tampa Graduate Theses and Dissertations.
https://digitalcommons.usf.edu/etd/10209
