Journal Published Online: 21 January 2014
Volume 37, Issue 2

Axial Uplift Behavior of Drilled Shafts in Gobi Gravel



Drilled shafts have been applied to withstand the axial uplift load for transmission towers in Gobi, a common geological formation in Northwest China. This study elucidated the uplift behavior of drilled shafts in the Gobi gravel. Nineteen full-scale drilled shafts were installed at six sites, and pullout load testing was conducted for each drilled shaft. The load test results were interpreted using four representative uplift capacity interpretation criteria to define various elastic, inelastic, and “failure” states for each drilled shaft. The results were interrelated to establish a generalized correlation among these states using a mean uplift load-displacement curve for drilled shafts in the Gobi gravel, which was compared with parallel studies in gravelly and cohesive soils. Using the hyperbolic fitting method, normalized curves were developed by approximating the load-displacement curves for all load tests. Explicit hyperbolic curve-fitting constants were suggested at different confidence levels, and normalized load-displacement curves were presented by considering the uncertainty in the prediction. The slope tangent and Chin methods represented the lower and upper bounds, respectively. The L1L2 method was found to be appropriate for interpreting the uplift capacity. Normalizing the load-displacement curves reduced scattering in the curves. The normalized load-displacement curves can be used in a drilled shaft design that considers capacity and displacement together.

Author Information

Qian, Zeng-Zhen
School of Engineering and Technology, China Univ. of Geosciences, Beijing, CN
Lu, Xian-Long
China Electric Power Research Institute, Beijing, CN
Yang, Wen-Zhi
China Electric Power Research Institute, Beijing, CN
Pages: 14
Price: $25.00
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Stock #: GTJ20130083
ISSN: 0149-6115
DOI: 10.1520/GTJ20130083