Bearing capacity on sand overlying clay soils: experimental and finite-element investigation of potential punch-through failure

Lee, K.K.; Cassidy, Mark; Randolph, Mark

doi:10.1680/geot.12.p.175

Cited by 108 publications

(80 citation statements)

References 23 publications

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“…The bearing capacity of footings on sand with a weak layer Valore, Ziccarelli and Muscolino vertical settlement of the footing base is imposed instead, so as to reproduce the real experimental procedure and accounting for the high stiffness of the footing and for the roughness of its base (Lee et al, 2013). The finite-element code Plaxis 2D (Plaxis, 2008) was used.…”

Section: Geotechnical Research Volume 4 Issue Gr1mentioning

confidence: 99%

The bearing capacity of footings on sand with a weak layer

Valore

Ziccarelli

Muscolino

2017

Geotechnical Research

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Minor details of the ground, such as thin weak layers, shear bands and slickensided surfaces, can substantially affect the behaviour of soil-footing and other geotechnical systems, despite their seeming insignificance. In this paper, the influence of the presence of a thin horizontal weak layer on the ultimate bearing capacity of a strip footing on dense sand is investigated by single-gravity tests on small-scale physical models of the soil-footing system. The test results show that the weak layer strongly influences both the failure mechanism and the ultimate bearing capacity if its depth is lower than about four times the footing width. It is found that the presence of a thin weak layer can cause decreases of the ultimate bearing capacity of up to 80%. Numerical simulations, by finite-element analysis, of the behaviour of the reduced-scale models are able to capture the failure mechanism and the ultimate bearing capacity correctly, only if the mean equivalent constant value of the secant angle of shearing resistance used in calculations is selected, taking into account the curvature of the shear strength envelope of the sand within the very low normal stress range existing in the tested models.

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Section: Geotechnical Research Volume 4 Issue Gr1mentioning

confidence: 99%

The bearing capacity of footings on sand with a weak layer

Valore

Ziccarelli

Muscolino

2017

Geotechnical Research

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“…Ã has been sought (Lau and Bolton, 2011b;Lee et al, 2013). Of course, under 1g conditions, the shear strength parameters in the low-stress range strongly depend on the effective stress level; consequently, they vary, within the relevant soil volume, from 'lower' values in the zone beneath the footing (where the effective normal stresses are relatively large) to higher values within the passive zone, where the stresses in tested 1g physical models are low or extremely low Bolton, 2011a, 2011b).…”

Section: Back-analysismentioning

confidence: 99%

Centrifuge tests on strip footings on sand with a weak layer

Ziccarelli

ValoreCalogero

Rino

et al. 2017

Geotechnical Research

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Tests on small-scale physical models of a strip footing resting on a dense sand bed containing a thin horizontal weak soil layer were carried out at normal gravity (1 g ). The results, reported in a companion paper, point out that the weak layer plays an important role in the failure mechanism and the ultimate bearing capacity of the footing if it falls within the ground volume relevant to the behaviour of the sand–footing system. The same problem was also investigated by means of centrifuge tests on reduced-scale models at 25 g and 40 g . The results of these tests, reported and discussed in this paper, confirm that failure mechanisms are governed substantially by the presence of the weak layer if its depth does not exceed a critical value and highlight marked scale effects involving the ultimate bearing capacity related essentially to the mean equivalent stress level in the soil beneath and around the footing. Equivalent bearing capacity factors, [Formula: see text], for footings on a dense sand bed containing a thin weak layer are derived from experimental results and are proposed in the paper.

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“…A series of 30 geotechnical centrifuge experiments on the installation of circular flat and spudcan foundations in sand overlying clay was reported in Lee et al (2013). This database, obtained from tests conducted on two consistent samples in a drum centrifuge, provides the most comprehensive set of ratios of sand height to diameter for conceptual model calibration.…”

Section: Introductionmentioning

confidence: 99%

Bearing capacity on sand overlying clay soils: a simplified conceptual model

Lee¹,

Randolph²,

Cassidy³

2013

Géotechnique

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The derivation of a new conceptual model for predicting the peak penetration resistance of circular footings installed vertically into sand overlying soft clay is presented in this paper. Based on visualisation experiments and finite-element analyses, a failure mechanism of a frustum of sand being forced into the underlying clay, with the outer angle reflecting the dilation in the sand, is assumed. The analytical basis of the new conceptual model follows the approach for silo analysis, and takes into account the stress level and dilatant response of the sand. A comprehensive analysis of the performance of the new model, and other existing analytical methods, in retrospectively predicting the peak resistance of a database of 49 geotechnical centrifuge tests is provided. Significant improvements over existing punching shear and load spread models are shown, as a result of incorporating the strength properties of the sand in a consistent manner. The new model has application to the offshore mobile 'jack-up' industry, where inaccurate predictions of peak capacity in layered soils continue to cause damaging punch-through failures.

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Bearing capacity on sand overlying clay soils: experimental and finite-element investigation of potential punch-through failure

Cited by 108 publications

References 23 publications

The bearing capacity of footings on sand with a weak layer

The bearing capacity of footings on sand with a weak layer

Centrifuge tests on strip footings on sand with a weak layer

Bearing capacity on sand overlying clay soils: a simplified conceptual model

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