This report provides a simplified method to be used for evaluating the skin friction and tip resistance of axially loaded drilled shafts. A summary of literature and current practice was completed and then a comprehensive set of field and laboratory tests was performed. Several soil samples were collected from different sites from Arizona and surrounding states. Large scale direct shear apparatus was developed and used to determine the friction between soil and concrete. Finite element analyses were conducted on several prototype cases to determine effect of soil parameters such as dilation on the skin friction values. A step-by-step simplified approach was introduced to determine the skin and tip resistance of drilled shaft foundations in gravelly soils. An example application was presented to guide users in utilizing the simplified approach.

As a major component of the Climate Assessment Project for the Southwest, this study is part of a larger effort to assess the vulnerability of natural and human systems to climate variability and change in the southwestern U.S. As importantly, this assessment seeks to fulfill the project’s larger mission of working directly with communities to improve their ability to respond adequately and appropriately to climatic events and climate change. The goal of this study is to demonstrate the utility of a rapid ethnographic approach for (1) conducting a community-level assessment of climate related vulnerability and (2) extending the findings to other assessments.