Alternative Title
Paper No. 1.25
Location
St. Louis, Missouri
Date
10 Mar 1998, 9:00 am - 12:00 pm
Abstract
Long-term set-up of piles in non-cohesive soil can roughly be divided into two time-dependent causes: stress relaxation leading to an increase in horizontal stress on the shaft, and soil aging leading to an increase in stiffness and dilatancy of the soil. The present paper describes a field test in which driven concrete piles, instrumented with earth pressure cells on the shaft, were tested dynamically for static pile capacity determination at different times. The objective was to measure tl1c increase in horizontal stress due to stress relaxation and compare it with the set-up evaluated from the dynamic tests. The results show that only a fifth of the long term set-up was due to stress relaxation. Il was concluded that the remaining set-up was due to soil aging and the ruling mechanism was most probably increasing dilatancy with time at the pile-soil interface. The paper provides a discussion of this mechanism in light of the presented results.
Department(s)
Civil, Architectural and Environmental Engineering
Meeting Name
4th Conference of the International Conference on Case Histories in Geotechnical Engineering
Publisher
University of Missouri--Rolla
Document Version
Final Version
Rights
© 1998 University of Missouri--Rolla, All rights reserved.
Creative Commons Licensing
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.
Document Type
Article - Conference proceedings
File Type
text
Language
English
Recommended Citation
Axelsson, Gary, "Long-term Increase in Shaft Capacity of Driven Piles in Sand" (1998). International Conference on Case Histories in Geotechnical Engineering. 57.
https://scholarsmine.mst.edu/icchge/4icchge/4icchge-session01/57
Long-term Increase in Shaft Capacity of Driven Piles in Sand
St. Louis, Missouri
Long-term set-up of piles in non-cohesive soil can roughly be divided into two time-dependent causes: stress relaxation leading to an increase in horizontal stress on the shaft, and soil aging leading to an increase in stiffness and dilatancy of the soil. The present paper describes a field test in which driven concrete piles, instrumented with earth pressure cells on the shaft, were tested dynamically for static pile capacity determination at different times. The objective was to measure tl1c increase in horizontal stress due to stress relaxation and compare it with the set-up evaluated from the dynamic tests. The results show that only a fifth of the long term set-up was due to stress relaxation. Il was concluded that the remaining set-up was due to soil aging and the ruling mechanism was most probably increasing dilatancy with time at the pile-soil interface. The paper provides a discussion of this mechanism in light of the presented results.
