Model testing of tripod caisson foundations in silty clay subjected to eccentric lateral loads

Shili MA, Liquan XIE, Tsung-Chow SU

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Front. Struct. Civ. Eng. ›› 2023, Vol. 17 ›› Issue (3) : 467-476. DOI: 10.1007/s11709-023-0933-6
RESEARCH ARTICLE
RESEARCH ARTICLE

Model testing of tripod caisson foundations in silty clay subjected to eccentric lateral loads

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Abstract

In this study, model tests were conducted to investigate the bearing capacities of tripod caisson foundations subjected to eccentric lateral loads in silty clay. Lateral load–rotation curves of five eccentric-shaped tripod suction foundations were plotted to analyze the bearing capacities at different loading angles. It was observed that the loading angle significantly influenced the bearing capacity of the foundations, particularly for eccentric tripod caisson foundations. Compared with eccentric tripod caisson foundations, the traditional tripod foundation has a relatively high ultimate lateral capacity at the omnidirectional loading angle. By analyzing the displacement of the caissons, a formula for the rotational center of the tripod caisson foundation subjected to an eccentric lateral load was derived. The depth of the rotation center was 0.68–0.92 times the height of the caisson when the bearing capacity reached the limit. Under the undrained condition, suction was generated under the lid of the “up-lift” caisson, which helps resist lateral forces from the wind and waves.

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Keywords

tripod caisson foundation / silty clay / eccentric lateral capacity / model tests

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Shili MA, Liquan XIE, Tsung-Chow SU. Model testing of tripod caisson foundations in silty clay subjected to eccentric lateral loads. Front. Struct. Civ. Eng., 2023, 17(3): 467‒476 https://doi.org/10.1007/s11709-023-0933-6

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Notations

D, L: caisson diameter, skirt length
e: loading height
θ: rotation of foundation
H: lateral loading
β: loading angle
γ′: average effective gravity of soil
φ: effective internal friction angle
Hult,t, Hult,s: ultimate lateral capacities of tripod caisson foundation and single-suction caisson, respectively
zp: horizontal distance of foremost foundation in loading direction
dp: depth of rotation center
lb, lt: displacements measured by two horizontal LVDTs on the loading rod
svI, svII, svIII: displacements of loading rod and three vertical LVDTs on lid of caissons I, II, and III, respectively
ht, hb: heights of top and bottom LVDTs from the ground surface, respectively
FsvI: vertical displacement of caisson I
P(svII ∨ svIII): vertical displacement of caisson II or III
SFP: center distance between caissons I and II (or III) in loading direction
V: normalized penetration velocity
v: loading rate
cv: vertical coefficient of consolidation for soil
P: suction under lid

Acknowledgements

The work presented in this paper was supported by the National Natural Science Foundation of China (Grant No. 51479137).

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2023 Higher Education Press
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