Abstract:
Pile foundations are often driven in intermediate geomaterials (IGMs) to attain higher resistances in order to meet the increasing load demand, satisfy Load and Resistance Factor Design (LRFD) specifications, improve design efficiency, and reduce construction challenges. IGMs are transitional geomaterials that possess a high natural variability. However, these geomaterials are not well defined and characterized in the design and construction of driven piles. Furthermore, methods to estimate the resistances of piles in IGMs have yet been developed. This paper presents the recent research development using over 150 pile load test data to comprehensively address current challenges with pile foundations in IGMs. A methodology is present to classify soft rocks and soil-based IGMs with the intention to reduce pile design and construction uncertainties. Inherent variability and geological uncertainties of IGMs are evaluated using geostatistics to optimize a geotechnical investigation plan. New static analysis methods are developed and validated to improve the estimation of shaft resistance and end bearing of piles in IGMs. New procedures to model pile driving in IGMs using wave equation analysis program are proposed to improve the construction control efficiency. Time-dependent pile resistances in different IGMs are investigated. LRFD resistance factors are calibrated using probability-based methods to achieve a target design reliability. Finally, static pile load test results are completed, and the field results are used to develop recommendations for the design and construction of driven piles in IGMs.