Bearing Capacity Predictions of Sand Overlying Clay Based on Limit Equilibrium Methods

Okamura, Mitsu; Takemura, Jiro; Kimura, Tsutomu

doi:10.3208/sandf.38.181

Cited by 67 publications

(38 citation statements)

References 9 publications

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“…By ignoring the properties of the upper sand layer (since even in the punching shear approach the frictional resistance through the sand is expressed in terms of the strength of the underlying clay), both methods provide oversimplified approaches whereby the ratio of q peak to the bearing capacity of the underlying clay increases as a simple quadratic function of the ratio of the upper sand thickness to the foundation diameter, H s /D. Two alternative prediction methods have been developed more recently by Okamura et al (1998) and Teh (2007). Okamura et al (1998) proposed a new limit equilibrium method with a failure mechanism that combines the concept of the projected area method and the punching shear method, as shown in Fig.…”

Section: Introductionmentioning

confidence: 98%

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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Section: Introductionmentioning

confidence: 98%

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

Lee¹,

Randolph²,

Cassidy³

2013

Géotechnique

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“…Kim and Yamamoto (2004) and Mizuno and Tsuchida (2002) reported that Okamura et al's (1998) failure mechanism obtained bearing capacity was close to the finite element method's results in comparison to the other bearing capacity theories. In this study, the authors modeled a clay layer underlying sand layer based on failure mechanisms from centrifuge tests performed by Okamura et al (1998), as shown in Figure 4. A clay layer underlying the sand layer with friction angle 35 o was modeled by 26 discrete elements.…”

Section: Comparison With Other Numerical Methodsmentioning

confidence: 99%

“…Representative examples for multilayer soils are shown in Figure 3. In order to evaluate the bearing capacity determination of a clay layer underlying a sand layer shown in Figure 3(a), the semi-empirical approaches (Meyerhof 1974;Hanna and Meyerhof 1980), numerical approach (Kim and Yamamoto 2004), and model tests were performed (Kim and Yamamoto 2004;Mizuno and Tsuchida 2002;Okamura et al 1998). Kim and Yamamoto (2004) and Mizuno and Tsuchida (2002) reported that Okamura et al's (1998) failure mechanism obtained bearing capacity was close to the finite element method's results in comparison to the other bearing capacity theories.…”

Section: Comparison With Other Numerical Methodsmentioning

confidence: 99%

Evaluation of Bearing Capacity for Multi-Layered Clay Deposits with Geosynthetic Reinforcement using Discrete Element Method

Park

Lee

2010

Marine Georesources & Geotechnology

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A stability analysis of reinforced foundation soil is presented in this paper. A method based on the discrete element method (DEM) is suggested for calculating the bearing capacity on strip footings over multilayer soils reinforced with a horizontal layer of geosynthetics. The proposed method can estimate the ultimate bearing capacity and the distribution of tensile force developed in the geosynthetics of the footing system by Winkler springs to account for the compatibility between soil blocks and tensile elements to consider the tensile behavior between soil and geosynthetics. For footings on various multilayer soils with or without reinforcement of geosynthetics, the results of the method were compared to the field test results as well as to those obtained by various methods proposed by other researchers.

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“…Okamura et al [8] compared the factors as thickness of sand, strength of clay and width, shape and embedment of footing, as well as calculated bearing capacities to the results of wellconditioned centrifuge tests by [6] to verify the validity of the previous methods. It has been confirmed that reasonable assumptions in which the variation of the shape of the sand block and the forces related to the factors taken into consideration are important to obtain a reasonable prediction, as shown in Fig.(3).…”

Section: Analytical Approachesmentioning

confidence: 99%

“…A method called the projected area method was proposed by Yamaguchi; as reported by [8]; as shown in Fig. (2.a).…”

Section: Analytical Approachesmentioning

confidence: 99%

Bearing Capacity of Sand Overlying Clay

2015

IJSR

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Soil naturally occurs in deposited layers. Each layer of the soil may be assumed to be homogeneous, although the strength properties of adjacent layers are quite different. The present study aims mainly to investigate the behavior of footing under vertical central load placed on the surface of two layered soil. The study has been carried out for the bearing capacity of sand overlying clay. Experimental and numerical works have been carried out. A review of previous researches is given and a discussion is presented of the dimensionless relationships that govern the behavior of this type of foundation. The results are presented in terms of the ultimate bearing capacity, load-settlement curves, and non-dimensional relationships to show the effect of upper layer thickness to footing width ratio, (H/B), and the strength of the upper layer soil on the bearing capacity. In addition, modes of failure of the foundation soil system are also presented.

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Bearing Capacity Predictions of Sand Overlying Clay Based on Limit Equilibrium Methods

Cited by 67 publications

References 9 publications

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

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

Evaluation of Bearing Capacity for Multi-Layered Clay Deposits with Geosynthetic Reinforcement using Discrete Element Method

Bearing Capacity of Sand Overlying Clay

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