Skirted Foundation Research Articles

Experimental and Numerical Evaluation Performance of Strip Foundation Reinforced with Steel Slag Columns Compared to Skirted Foundation

Experimental and Numerical Evaluation Performance of Strip Foundation Reinforced with Steel Slag Columns Compared to Skirted Foundation

Influence of Spudcan Penetration on Adjacent Skirted Foundation in Uniform Clay

Influence of Spudcan Penetration on Adjacent Skirted Foundation in Uniform Clay

Experimental and Numerical Parametric Studies on Inclined Skirted Foundation Resting on Sand

Skirted foundation behavior is enhanced due to the increase in skirt angle. The bearing capacity of the inclined skirted foundations resting on sandy soil is influenced by the soil parameters and skirting systems. Finite element analyses were carried out using Plaxis-3D software to find out the influence of the relative density, the internal friction angle of the supported soil, and the additional skirts on the bearing capacity of the inclined skirted foundations. The experimental work on a small physical scale was also carried out to support the numerical findings, which give an acceptable agreement. The findings revealed that the increase in relative density resulted in a significant increase in the bearing capacity of the inclined skirted foundation. In the same way, as the internal friction angle increases, the bearing capacity is affected by this increase, which improves the bearing capacity value. The effect of the additional skirts on the bearing capacity is observed to be neglected, and, in some cases, it causes a negative effect. The findings of this study contribute to a greater comprehension of the behavior of inclined skirted foundations and can assist in the future design of more efficient and effective foundation systems. Doi: 10.28991/CEJ-2023-09-07-017 Full Text: PDF

Prediction of Undrained Bearing Capacity of Skirted Foundation in Spatially Variable Soils Based on Convolutional Neural Network

Skirted foundations are widely used in offshore and subsea engineering. Previous studies have shown that soil undrained shear strength variability has a notable impact on probabilistic analyses of skirted foundation bearing capacity. This study proposes an efficient machine-learning method to predict the uniaxial bearing capacity factors of skirted foundations under pure horizontal and moment loads, without relying on traditional time-consuming random finite element methods. A two-dimensional convolutional neural network is adopted to capture the potential correlation between soil random fields and bearing capacity factors. The proposed CNN-based model exhibits satisfactory prediction performance with regard to coefficients of variation and scale of fluctuations in two directions. Specifically, coefficient of determination (R2) values exceed 0.97, while root mean square error (RMSE) values remain below 0.13 for the surrogate model. In addition, more than 96% of the predictions are associated with a relative error of 5% or less, providing evidence of the proposed 2D-CNN model’s satisfactory prediction performance.

Impact of eccentricity and depth-to-breadth ratio on the behavior of skirt foundation rested on dry gypseous soil

AbstractGypseous soils are considered one of the most problematic soils. The skirted foundation is an alternative technology that works to improve the bearing capacity and reduce settlement. This paper investigates the use of square skirted foundations resting on gypseous soil subjected to concentric and eccentric vertical load with eccentricity values of 4, 8, and 17 mm in 16 experimental model tests. To obtain the results by using this type of foundation, a small-scale physical model was designed to obtain the load–settlement behavior of the square skirted foundation; the dimension of the square footing is 100 mm × 100 mm with 1 mm thickness, the skirt depth (Ds) was 0.5, 1, and 1.5B(whereBis the footing width). The footing rests on dry gypseous soil with a relative density of 33%. The tests show that the gypsum content of the soil is 59%. The result shows that the highest bearing capacity for the square shape footing withDs/B= 1.5 subjected to concentric load results in an improvement ratio of 190%. For the eccentric load, withDs/B = 1.5, the increase in bearing capacity is about 120% ate= 8 mm when compared with using a foundation without a skirt.

Improving Bearing Capacity by Skirted Foundation: A Review Study

The difficulty that faces the geotechnical engineers how to find the alternative and effective method to improve bearing capacity and reduce foundation settlement. Therefore, the skirt is considered one of the methods to improving the shallow foundation bearing capacity on different soil. The mechanism of skirt work is confinement soil below the foundation and decrease settlement of the foundation. Soil engineers are worked to devise this method as an alternative to pile foundation for conventional buildings. This paper reviews most of these studies of skirted foundations with different types of soil including laboratory tests, field tests, centrifuge models, numerical method and theoretical analysis; these studies are used in investigation the behaviors skirted foundations.

Experimental Investigation of Skirted Foundation in Sand Subjected to Rapid Uplift

Abstract This paper reports results from 1g model tests carried out under single gravity on a skirted foundation installed in sand and subjected to a rapid uplifting force. The effects of displacement rates ranging from 5 mm/s to 450 mm/s on the ultimate capacity, suction pressure inside the skirt compartment, and time of extraction were investigated. Test results indicate that the displacement rate significantly affected the magnitude of uplift resistance, as well as the magnitude of suction under the foundation lid, but had little effect on the relationship between stress and the displacement of the foundation. The shapes of the uplift capacity-displacement curve and the suction-displacement curve were similar for all experimental displacement rates.

Optimal Skirt Spacing for Subsea Skirted Foundation Considering Floating Stability

A hydraulics model is built in Moses to find the optimal internal skirt spacing for the maximum floating stability of the skirted foundation. The results show that the increase in the internal skirts’ number can help improve the floating stability of the skirted foundation. However, with the increase in the internal skirts’ number, the improvement of floating stability becomes more and more weak. In this study, an optimal number of four are found for the internal skirt spacing. Moreover, to testify the feasibility of internal skirt spacing, a practical project is modeled, which indicates that the optimal internal skirt spacing can satisfy the requirements of towing.

Skirted foundation to mitigate spudcan punch-through on sand-over-clay

Mitigation of spudcan punch-through is one of the principal aspects for inclusion in the ISO standard 19905-1. This paper investigates the potential for using skirted foundations as an alternative to spudcans in an attempt to mitigate punch-through failure of jack-up rigs during installation and preloading in sand-over-clay deposits. A series of centrifuge model tests is undertaken on a spudcan and two skirted foundations, varying the length of the skirt relative to the foundation diameter. The thickness of the sand layer is also varied to cover a range of practical interest. The results from this study confirm that the use of skirted foundations as an alternative to spudcans can eliminate the potential of punch-through failure on sand-over-clay deposits. The degree of post-peak bearing reduction, one of the key measures of the severity of punch-through failure, is shown to be linked directly to the effective sand layer thickness beneath the foundations. Skirted foundations assist in mitigating the severity of punch-through failure by reducing the effective sand layer thickness.

Experimental Study on the Behavior of Skirted Foundation Rested on Soft Clayey Soils

Experimental Study on the Behavior of Skirted Foundation Rested on Soft Clayey Soils

Effect of Gapping on the Transient and Sustained Uplift Capacity of a Shallow Skirted Foundation in Clay

ABSTRACT Shallow skirted foundations are an attractive solution for supporting offshore platforms that are subject to uplift due to overturning or buoyancy loading. In practice, gapping may occur along the skirt-soil interface leading to a detrimental effect on uplift capacity. This paper presents results from beam centrifuge tests that investigated the effect of gapping on the transient and sustained uplift capacity of shallow skirted foundations. The results indicate that the transient uplift capacity following the formation of a gap was around 60% of that for intact soil contact along the skirt-soil interface. Under sustained uplift, the time to accumulate a displacement of 1% of the foundation diameter was reduced by an order of magnitude due to the presence of a gap.

Effect of Embedment and Spacing of Cojoined Skirted Foundation Systems on Undrained Limit States under General Loading

A foundation system may involve more than a single footing with an arrangement such that the footings are sufficiently closely spaced that adjacent footings interact. Vertical, horizontal, and moment capacity of multifooting foundation systems are potentially dependent on footing interaction, and in particular overturning capacity can be significantly enhanced by the structural rigidity of a multifooting foundation system. There is no established procedure for the calculation of bearing capacity of a shallow foundation system comprising cojoined footings and ad hoc approaches may simply involve summing the ultimate limit states of the individual footings as if they acted independently; neglecting additional capacity of the system available from the kinematic constraint provided by the structural connection between the footings. Plane strain finite-element analyses have been carried out to investigate the undrained ultimate limit states under general loading of skirted two-footing foundation systems at various normalized spacing compared to a single skirted footing of equal bearing area and embedment ratio.

An Experimental Investigation of a Shallow Skirted Foundation Under Compression and Tension

Shallowly embedded skirted foundations are an attractive alternative to piles for jacket structures and buoyant facilities as they can resist uplift but are cheaper to install than deep foundations. Bearing capacity of shallow skirted foundations in compression is moderately well understood while there is still considerable uncertainty over uplift capacity, particularly for loading sustained over a period of time. This paper reports results from beam centrifuge tests on a shallow skirted foundation in clay, subjected to uplift and compression. Rapid and sustained loading is considered and the effects of consolidation stress level and stress history on undrained capacity and sustained load response are reported.

Bearing Response of Skirted Foundation on Nonhomogeneous Soil

Circular skirted offshore foundations on nonhomogeneous soil have been studied numerically, analytically, and physically, with the offshore sediment simulated as a cohesive soil with strength increasing linearly with depth. In the numerical analysis, the h-adaptive FEM is adopted to provide an optimal mesh, in which a strain-superconvergent patch recovery error estimator and mesh refinement with subdivision concept are used. This paper presents two main studies of circular skirted foundations on nonhomogeneous soil, consisting of a bearing-capacity study and a large penetration study. The bearing capacity of the foundations is studied with the degree of nonhomogeneity (kD/suo) of soil up to 30, different skirt roughness and skirt depth up to five times the foundation diameter (i.e., Df/D = 5), using an h-adaptive FEM and extended upper-bound method. The bearing-capacity values and soil flow mechanisms are discussed. In the foundation large penetration study, circular skirted foundations penetrating into normally consolidated and overconsolidated soils are tested physically in the centrifuge and analyzed numerically using the h-adaptive remeshing and interpolation technique with small strain method for soil large deformation analysis. The load-displacement responses from centrifuge test data and finite-element results are compared.