| The skin friction behavior of drilled shafts was investigated. Literature review provided a basic understanding of skin friction development and computation by several methods. The properties, origins, and types of cemented soils were discussed, and classification of cemented soils was evaluated. Layering of different types was identified in cemented deposits around the Phoenix area, and the implication of the form of the profile to the deposition history was explored. A simple pedological stage system was selected for classification, to be used together with standard geotechnical descriptions of soil.; Laboratory measurements of soil strength and carbonate content were made for a large number of samples. The results were statistically evaluated to determine the effect of the carbonate on strength. Surprisingly, only very weak correlations were identified, although always the carbonate caused an increase in the strength. The portion of the strength resulting from structure was related to carbonate content, beyond a threshold value.; Load transfer curves for skin friction along drilled shafts were identified for several cemented soil sites. Among these were load tests conducted on small scale shafts at the Arizona State University Research Park. The load transfer curves all showed a shift toward higher deflections at peak strength than for uncemented soils. Deflections at peak skin friction were typically one inch (25 mm) or more. Using a finite element model and an elastic-plastic constitutive relationship, the curve shape was shown to be potentially caused by layering or by the high shear strength of cemented soils. The impact of the shape of the load transfer curves for cemented soils was to increase the deflection required to attain a given fraction of ultimate load. |
