Pile Aging in Cohesive Soils

Doherty, Paul; Gavin, Kenneth

doi:10.1061/(asce)gt.1943-5606.0000884

Cited by 24 publications

(4 citation statements)

References 16 publications

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“…where s = √ 𝐬 ∶ 𝐬∕2 is the square root of the second invariant of the deviatoric stress tensor; 𝑣 𝑧 is the excess volume per STZ; and 𝑠 0 is the initial yield stress. It is noted that the exponential term in Equation (5) suggests that STZs transition faster with higher stress ratio s∕𝑝 but lower compactivity 𝜒. It is seen from Equation (4) that increasing 𝜒 has a competing effect on the plastic strain rate as the STZ density increases but the STZ transition rate decreases.…”

Section: Plasticitymentioning

confidence: 99%

“…1,2 They play critical roles in foundation engineering, such as the long-term settlement of superstructures built on clay 3 and the setup of piles installed in clay. 4,5 Reliable modelling of the time-dependent behaviours of clay under complex loading conditions is of great significance but remains challenging due to the lack of a unified, robust yet handy theoretical framework to describe these time-dependent characteristics.…”

Section: Introductionmentioning

confidence: 99%

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A shear‐transformation‐zone model for time‐dependent behaviours of clay

Guo,

Li,

Yang

2024

Num Anal Meth Geomechanics

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A shear‐transformation‐zone (STZ) model is proposed for time‐dependent behaviours of clay, in which the viscoplastic deformation is described by the evolution of a temperature‐like state variable. The model is featured by rate‐dependent dilatancy and a unique critical state stress ratio. In its present form, it has nine parameters, most of which can be handily calibrated, and can predict the rate‐dependent undrained shear strength, primary, and secondary creep, as well as stress relaxation for normally consolidated clay under complex stress paths using a single set of parameters. The capabilities of the model have been verified by available experimental results on five different clays.

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Section: Plasticitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A shear‐transformation‐zone model for time‐dependent behaviours of clay

Guo,

Li,

Yang

2024

Num Anal Meth Geomechanics

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“…Postconsolidation gains in shaft capacity are referred to as aging (e.g., Doherty and Gavin 2013). Eq.…”

Section: Optimization Analysesmentioning

confidence: 99%

CPT-Based Axial Capacity Design Method for Driven Piles in Clay

Lehane

Liu

Bittar

et al. 2022

J. Geotech. Geoenviron. Eng.

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There are clear advantages in the establishment of reliable, direct cone penetration test (CPT) based methods for assessment of the axial capacity of driven piles. These advantages motivated the formation of a joint industry project (JIP) under the management of the Norwegian Geotechnical Institute (NGI), which initially led to the creation of a unified database of high-quality pile load tests in sand and clay. The unified database has the consensus approval of representatives of the profession and personnel in multiple companies from the offshore energy sector. This paper presents a component of the research from the second phase of the JIP, which had the objective of developing a new CPT-based method for driven piles in clay to unify several CPT-based methods that are in use today. First, a rational basis for the CPT-based formulation is described, using trends from instrumented pile tests; the description facilitates an understanding of the approach and illustrates its empirical nature and limitations. The unified database was used to calibrate the formulation and it led to good predictions for an independent database of pile load tests and for measured distributions of shaft friction.

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“…They indicated that new findings with the piles could be employed to characterize more clearly the strong aging effects. Dohersty and Gavin (2013) made a field investigation in concrete pile aging in soft clay that was conducted over a period of 10 years. A simple reliability-based design example was presented to highlight the positive pile aging effect by showing the increasing reliability indices calculated from the measured pile capabilities at different time after pile installation.…”

mentioning

confidence: 99%

Estimating Pile Set-up Using 24-h Restrike Resistance and Computed Static Capacity for PPC Piles Driven in Soft Lousiana Coastal Deposits

2015

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In this paper, the CPT-based predicted ultimate pile resistances (R p ) were compared with the measured pile resistances (R m ) at different elapsed time for the piles driven into saturated soft clays where piles displayed significant set-up effect. The measured pile resistances were based on 115 restrike records collected from 95 production piles, and 74 records of 9 tested piles. The predicted ultimate pile resistances were calculated from the LCPC, the Schmertmann, and the de Ruiter-Beringen methods, respectively. With the significant pile set-up effect taken into account, the relationship between measured resistances and predicted capacities at different times after pile installation were investigated. The ratios of the measured pile resistances to the predicted capacities scattered in a large spectrum. The ratios fluctuated and stayed within a range of 0.6-1.6 for different CPT methods since end of initial driving until more than 2 months after pile installation. Plots of the ratios versus the predicted pile capacities using different CPT methods have revealed that the ratio (R m /R p ) presented a strong dependence on the predicted capacities. Great research efforts have been devoted to the analyses of the ratios of the 24-h measured resistance to the predicted capacity based on different CPT methods, in an attempt to find a feasible empirical correlation. It is found that a simple linear relationship exists between the quad root of the ratio and the predicted capacity. The developed empirical equations will give pile foundation engineers an insight into the ultimate resistances of driven piles demonstrating significant pile set-up effects. Pile set-up makes pile resistances grow with time, and it might be one of the reasons that cause the frequently reported large discrepancy between calculated static capacity and measured resistance at a certain time after pile installation.

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Pile Aging in Cohesive Soils

Cited by 24 publications

References 16 publications

A shear‐transformation‐zone model for time‐dependent behaviours of clay

A shear‐transformation‐zone model for time‐dependent behaviours of clay

CPT-Based Axial Capacity Design Method for Driven Piles in Clay

Estimating Pile Set-up Using 24-h Restrike Resistance and Computed Static Capacity for PPC Piles Driven in Soft Lousiana Coastal Deposits

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