Application of Reliability-Based Design to Piles in the Collapsible Argentinean Loess

ARRUA, PEDRO; FRANCISCA, FRANCO MATÍAS; REDOLFI, EMILIO ROQUE

Osaka, Japon

Conferencia; Sixteenth International Conference on Soil Mechanics and Geotechnical Engineering; 2005

International Society of Soil Mechanics and Geotechnical Engineering (ISSMGE)

Cast-in-place piles are the most commonly foundation type used in Cordoba city, Argentina. Foundation of buildings usually consists in concrete piles embedded in collapsible loess with the pile tip in contact with a lower and stiffer stratum, typically sand or cemented silt. Piles in loess are frequently designed using safety factor criteria for both, short- and long-term behavior. Piles function as a combination of friction resistance and end-bearing. Usually, there is no information about the reliability of piles since safety factors do not provide information on failure probability. A reliability analysis is implemented to predict the behavior of piles in the Argentinean loess. Reliability-based technique is used to compute the failure probability of a pile, for long- and short-term performance. Pile capacity is computed by theoretical formulation using classical bearing capacity factors. The skin resistance is estimated by the  method. Results show that failure probability for a short-term analysis is smaller than for long-term analysis. Also, failure probability increases as safety factor decreases. Even the safety factor can remain greater than one; the probability of having unacceptable deformations after soil saturates for long-term behavior becomes very high. Therefore, probability that soil saturates should be considered in pile design and design codes for soils in collapsible loessical soils.