A three-dimensional numerical comparison of bearing capacity and settlement of tapered and under-reamed piles

Vali, Ramin; Khotbehsara, Elham Mehrinejad; Saberian, Mohammad; Mehrinejad, M.; Jahandari, Soheil

doi:10.1080/19386362.2017.1336586

Cited by 52 publications

(18 citation statements)

References 16 publications

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“…Accordingly, the notations P, PSUR, and PDUR were assigned to represent (1) the pile with a uniform cross-section, (2) the single under-reamed pile and (3) the double under-reamed pile respectively. Following the literature of Prakashi [25] and the provisions mentioned in [10] for the under-reamed pile, a pile with a stem diameter of 0.3 m and a length of 4.5 m was selected [7,28]. The diameter of an under-reamed section was taken as 0.75 m i.e.…”

Section: Materials Properties and Problem Definitionmentioning

confidence: 99%

“…The clay was assumed saturated and under undrained condition (ϕ u = 0) obeying Mohr-Coulomb's failure criterion. Following George and Hari [7] and Vali et al [28], the unit weight (γ), elastic modulus (E) and Poisson ratio (ʋ) of soil were taken as 16 kN/m 3 , 20 MPa and 0.45. The cohesion of soil at the ground surface (c o ) was taken as 15 kPa whereas, with the consideration of linear variation, its magnitude at any given depth was calculated as per the following Eq.…”

Section: Materials Properties and Problem Definitionmentioning

confidence: 99%

“…Since the inception of under-reamed piles, many efforts and studies have been made to improve the performance and applicability of under-reamed piles in clay [1,6,7,18,19,[25][26][27][28]. Jennings and Henkel [11] initially started systematic studies on under-reamed piles in clay in South Africa.…”

Section: Introductionmentioning

confidence: 99%

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Effect of linearly increasing cohesion on the compression and uplift capacity of the under-reamed pile in clay

2020

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The present paper tries to explore the load-settlement behavior of an under-reamed pile subjected to either compressive or pull-out loading and installed in clay whose cohesion increases linearly with depth. In this regard, the finite element analysis was performed using OptumG2 software wherein the soil was assumed to obey Mohr-Coulomb's failure criterion under the undrained condition. For the selected pile geometry, the analysis was performed for the different values of linearly increasing cohesion and for the various shaft adhesion. The comparison of results for single and double under-reamed pile with a uniform diameter pile suggests that the provision of a bulb or under-reamed section to the pile helps in the increase in safe load and decrease in the settlement up to a certain value of the slope of linearly increasing cohesion. Additionally, the effect of no tension condition at the base of a pile on the safe and ultimate capacity was examined. The present results were found to compare well with that available literature. Keywords Cohesion • Safe load • Finite elements • Under-ream • Mohr-Coulomb List of symbols ϕ Soil friction angle c Cohesion at depth h c 0 Cohesion at the ground surface m Dimensionless factor to define the increase of cohesion with depth c b Cohesion at base

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Section: Materials Properties and Problem Definitionmentioning

confidence: 99%

Section: Materials Properties and Problem Definitionmentioning

confidence: 99%

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Effect of linearly increasing cohesion on the compression and uplift capacity of the under-reamed pile in clay

2020

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“…As reported by Yu, cavity expansion methods in Geomaterials have been developed since 1950s, and their wide implications lead to the cavity expansion theory as a useful and simple tool for modelling many complex geotechnical problems, including in situ soil testing (eg, Ahmadi and Dariani; Mo et al; Vali et al) and tunnelling (eg, Yang et al; Fang; et al Mo and Yu; Wang et al). Numerous analytical and numerical solutions have been proposed using increasingly sophisticated constitutive soil models by applying the principles of continuum mechanics .…”

Section: Introductionmentioning

confidence: 99%

“…Dislocation-based methods initially proposed by Elsworth 31 provided an alternative approximate method to accommodate the fluid pressure dissipation under partially drained conditions, while a pseudo-elastic material was assumed together with an incompressible flow field and a stress-decouple solution was employed to note the influence of soil rigidity to the penetration rate responses. 32 As reported by Yu, 33 cavity expansion methods in Geomaterials have been developed since 1950s, 34,35 and their wide implications lead to the cavity expansion theory as a useful and simple tool for modelling many complex geotechnical problems, including in situ soil testing (eg, Ahmadi and Dariani; 36 Mo et al; 37 Vali et al 38 ) and tunnelling (eg, Yang et al; 39 Fang; et al 40 Mo and Yu; 41 Wang et al 42 ). Numerous analytical and numerical solutions have been proposed using increasingly sophisticated constitutive soil models by applying the principles of continuum mechanics.…”

Section: Introductionmentioning

confidence: 99%

A cavity expansion–based solution for interpretation of CPTu data in soils under partially drained conditions

Gao

Yang

et al. 2020

Num Anal Meth Geomechanics

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Summary A cavity expansion–based solution is proposed in this paper for the interpretation of CPTu data under a partially drained condition. Variations of the normalized cone tip resistance, cone factor, and undrained‐drained resistance ratio are examined with different initial specific volume and overconsolidation ratio, based on the exact solutions of both undrained and drained cavity expansion in CASM, which is a unified state parameter model for clay and sand. A drainage index is proposed to represent the partially drained condition, and the critical state after expansion and stress paths of cavity expansion are therefore predicted by estimating a virtual plastic region and assuming a drainage‐index–based mapping technique. The stress paths and distributions of stresses and specific volume are investigated for different values of drainage index, which are also related to the penetration velocity with comparisons of experimental data and numerical results. The subsequent consolidation after penetration is thus predicted with the assumption of constant deviatoric stress during dissipation of the excess pore pressure. Both spherical and cylindrical consolidations are compared for dissipation around the cone tip and the probe shaft, respectively. The effects of overconsolidation ratio on the stress paths and the distributions of excess pore pressure and specific volume are then thoroughly investigated. The proposed solution and the findings would contribute to the interpretation of CPTu tests under a random drained condition, as well as the analysis of pile installation and the subsequent consolidation.

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Optimizing the Bearing Capacity of Pile Foundation in Clay

Majumder

Chakraborty

2022

Lecture Notes in Civil Engineering

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A three-dimensional numerical comparison of bearing capacity and settlement of tapered and under-reamed piles

Cited by 52 publications

References 16 publications

Effect of linearly increasing cohesion on the compression and uplift capacity of the under-reamed pile in clay

Effect of linearly increasing cohesion on the compression and uplift capacity of the under-reamed pile in clay

A cavity expansion–based solution for interpretation of CPTu data in soils under partially drained conditions

Optimizing the Bearing Capacity of Pile Foundation in Clay

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