Evaluation of Tip Capacity Analysis Model for Drilled Shafts in Gravelly Soils

Abstract:

This paper examines an analysis model for predicting the tip capacity of drilled shaft foundations under gravelly soils. Forty one static compression load test data are utilized for this purpose. Comparison of predicted and measured results demonstrates that the prediction model greatly overestimates the tip capacity of drilled shafts. Further assessment on the model reveals a greater variation in three coefficients; the effective overburden pressure ( ), the overburden bearing capacity factor (Nq); and the bearing capacity modifier for soil rigidity (ζqr). These factors are modified from the back-analysis of the drilled shaft load test results. Varying effective shaft depths are considered for the back-calculation to explore their effects on capacity behavior. Based on the analyses, the recommended effective shaft depth for the evaluation of effective overburden pressure is limited to 15B (B=shaft diameter). The Nq and ζqr are enhanced while maintaining their basic relationship with the soil effective friction angle, in which the Nq increases and ζqr decreases as increases. Specific design recommendations for the tip bearing capacity analysis of drilled shafts in gravelly soils are given for engineering practice.

• Periodical: Applied Mechanics and Materials (Volumes 284-287)
• Pages: 1320-1324
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.284-287.1320
• Online since: January 2013
• Authors: Yit Jin Chen, Maria Cecilia M. Marcos, T.H. Chu, H.W. Wu
• Keywords: Analysis Model, Drilled Shafts, Gravelly Soils, Load Test, MATLAB, Tip Capacity

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