Effect of Lattice Leg and Sleeve on the Transient Vertical Bearing Capacity of Deeply Penetrated Spudcans in Clay

Abstract

In estimating the vertical bearing capacity of spudcan foundation, the effect of the realistic lattice leg extending from the top of the spudcan is often ignored. This paper examines both the lattice leg and sleeve effect on the transient vertical bearing capacity of a spudcan foundation using centrifuge model tests and the numerical method. The lattice legs and sleeves are characterized by two parameters, namely, the opening ratio and area ratio. The experimental results indicate that the use of lattice legs and sleeves tends to increase the spudcan bearing capacity, compared with a spudcan without legs, in both normally consolidated and overconsolidated clay deposits. This effect appears to vary with the opening ratios and area ratios of the leg. The finding shows that the lattice legs and sleeves affect the transient vertical bearing capacity in three ways. First, it restricts soil backflow to the region of the spudcan footprint. Second, a small amount of the sleeve friction resistance is induced during spudcan penetration. Finally, a larger vertical influence zone of the soil beneath the spudcan footing is mobilized. All these effects contribute to an increase in the transient spudcan bearing capacity. It may provide a way to enhance the bearing capacity and uplift resistance of spudcan foundation by changing the configuration of the existing lattice leg.