Upper bound analysis of uplift piles in saturated clay and soil plug effect

Authors

Ke-wen ZHU, Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education, Tongji University, Shanghai 200092, China; Department of Geotechnical Engineering, Tongji University, Shanghai 200092, ChinaFollow
Jian YU, Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education, Tongji University, Shanghai 200092, China; Department of Geotechnical Engineering, Tongji University, Shanghai 200092, ChinaFollow
Mao-song HUANG, Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education, Tongji University, Shanghai 200092, China; Department of Geotechnical Engineering, Tongji University, Shanghai 200092, China

Abstract

A new mechanism is established and applied to the upper bound analysis of uplift piles in saturated clay. Upper bound solutions of uplift capacities of closed and open-ended piles are analyzed. The new mechanism is verified by comparing with elastoplastic finiteelement, existing lower bound and API solutions. Its reliability is assessed through case studies including one centrifuge test and two field tests. The effects of the pile length-diameter ratio, pile surface roughness, non uniformity of undrained soil strength and length of soil plug on the uplift bearing capacity are considered. A formulation predicting the net bearing capacity of closed-ended uplift piles in clay is proposed. The results show that an approximately linear relationship can be established between the normalized net bearing capacity coefficient and the pile length-diameter ratio for closed-ended piles. As for open-ended pipe piles, the ratio of the net bearing capacity coefficient of open ended pipe piles to that of closed-end piles tends to increase with the increase of the pile length-diameter ratio. The increase in the length of soil plug leads to an increase in the net bearing capacity coefficient of open-ended pipe piles. Therefore, the effect of soil plug should not be ignored.

Graphic Abstract

Recommended Citation

ZHU, Ke-wen; YU, Jian; and HUANG, Mao-song (2023) "Upper bound analysis of uplift piles in saturated clay and soil plug effect," Rock and Soil Mechanics: Vol. 44: Iss. 7, Article 3.
DOI: 10.16285/j.rsm.2022.6185
Available at: https://rocksoilmech.researchcommons.org/journal/vol44/iss7/3