Comparison of Measured and Predicted Skin Friction Values for Axially Loaded Drilled Shaft Foundations in Gravelly Soils

2005 ◽  
Author(s):  
Abdalla M. Harraz ◽  
William N. Houston ◽  
Kenneth D. Walsh ◽  
Courtland R. Perry ◽  
Sandra L. Houston
Keyword(s):  
Skin Friction ◽  
Drilled Shaft ◽  
Gravelly Soils ◽  
Axially Loaded ◽  
Drilled Shaft Foundations

Evaluation of uplift interpretation criteria for drilled shafts in gravelly soils

2012 ◽  
Vol 49 (1) ◽  
pp. 70-77 ◽  
Author(s):  
Yit-Jin Chen ◽  
Tsu-Hung Chu
Keyword(s):  
Drilled Shafts ◽  
Load Test ◽  
Drilled Shaft ◽  
Specific Design ◽  
Interpretation Criteria ◽  
Interpretation Criterion ◽  
Gravelly Soils ◽  
Load Tests ◽  
Drilled Shaft Foundations ◽  
Shaft Failure

Representative interpretation criteria are examined in this paper to evaluate the capacity of drilled shaft foundations under axial uplift loading in gravelly soils. A large number of uplift shaft load tests for gravelly soils are used for analysis, and the interpretation criteria are applied to these load test data to establish a consistent uplift interpretation criterion. The statistical results show that the smaller the uplift displacement, the higher the coefficient of variation. In general, the displacements required to mobilize shaft failure load in gravelly soils are larger than those in non-gravelly soils. Based on these analyses, the relative merits and interrelationships of these criteria are established. Specific design recommendations for the evaluation of uplift drilled shaft capacity are given.

Nondestructive Diagnosis of Drilled Shaft Foundations

1998 ◽  
Vol 1633 (1) ◽  
pp. 120-127 ◽  
Author(s):  
Larry D. Olson ◽  
Marwan F. Aouad ◽  
Dennis A. Sack
Keyword(s):  
Quality Assurance ◽  
The United States ◽  
Ultrasonic Waves ◽  
Drilled Shaft ◽  
Two Dimensional Image ◽  
Existing Structures ◽  
Advantages And Disadvantages ◽  
Ct Data ◽  
Drilled Shaft Foundations ◽  
Concrete Placement

Nondestructive methods based on propagation of sonic and ultrasonic waves are being used increasingly in the United States and internationally for forensic investigations of existing structures and for quality assurance of new construction. Of particular interest is the quality assurance of newly constructed drilled shaft foundations. Many state departments of transportation specify nondestructive testing of drilled shaft foundations, particularly for shafts drilled and placed under wet construction conditions. For quality assurance of drilled shaft foundations of bridges, the crosshole sonic logging (CSL) and sonic echo and impulse response (SE/IR) methods routinely are used. In the CSL method, access tubes are installed in the shaft before concrete placement. SE/IR measurements require that the top of the shaft be accessible after concrete placement. Proper test setups, specifications, and case studies are presented to illustrate the advantages and disadvantages of each of these methods. Also presented are recommendations for repair when a defect is identified in a drilled shaft foundation. The CSL method is more effective for locating defects. CSL measurements are effective for determining anomalies and defects between two access tubes. However, an accurate image of the defect cannot be determined from a CSL test alone. The crosshole tomography (CT) method uses multiple CSL logs with varying receiver locations to produce a two-dimensional image of the defect. The CT method is discussed and a dataset obtained from a drilled shaft foundation is presented. CT data collection and analysis require more time than the CSL method, and the CT method is used only for critical drilled shaft foundations.

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