A non-linear load transfer method for determining the settlement of piles under vertical loading

Boonyatee, Tirawat; Lai, Van Qui

doi:10.1080/19386362.2017.1410337

Cited by 10 publications

(4 citation statements)

References 23 publications

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“…Figure 6 shows that the mobilized base resistance (i.e., Q b /(P/A)) increases when the distance L p decreases. In particularly this ratio rises swiftly from around 10% to more than 30% when L p becomes less than 10 m. This observation, in fact, corroborates well previous data for large diameter bored piles [1,10,17,38,44]. The longer the distance, the harder the base resistance can be mobilized.…”

Section: Model Inputs and Outputssupporting

confidence: 90%

“…While it is well understood that the axial bearing capacity of a pile is mainly contributed by its shaft friction and base (or toe) resistance, immense effort has gone to establishing different methods to estimate bearing capacity of piles over the past years. Many solutions are based on complex mathematical derivations and numerical analysis [14,27,38,41], while others employ empirical equations derived from field tests such as Standard Penetration Test (SPT value) [19,30,49], Cone Penetration Test (CPT) [22,36,67] and field static/dynamic load tests [10,20,30]. Despite these various solutions, a significant limitation that most conventional approaches commonly share is their limited consideration of past experience as well as data.…”

Section: Introductionmentioning

confidence: 99%

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Base resistance of super-large and long piles in soft soil: performance of artificial neural network model and field implications

2022

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This study aims to examine the performance of artificial neural network (ANN) model based on 1137 datasets of super-large (1.0–2.5 m in equivalent diameter) and long (40.2–99 m) piles collected over 37 real projects in the past 10 years in Mekong Delta. Five key input parameters including the load, the displacement, the Standard Penetration Test value of the base soil, the distance between the loading point and pile toe, and the axial stiffness are identified via assessing the results of field load tests. Key innovations of this study are (i) use of large database to evaluate the effect that random selection of training and testing datasets can have on the predicted outcomes of ANN modelling, (ii) a simple approach using multiple learning rates to enhance training process, (iii) clarification of the role that the selected input factors can play in the base resistance, and (iv) new empirical relationships between the pile load and settlement. The results show that the random selection of training and testing datasets can affect significantly the predicted results, for example, the confidence of prediction can drop under 80% when an average R2 > 0.85 is required. The analysis indicates predominant role of the displacement in governing the base resistance of piles, providing significant implication to practical designs.

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Section: Model Inputs and Outputssupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Base resistance of super-large and long piles in soft soil: performance of artificial neural network model and field implications

2022

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“…Considering the similarity between the anchor-soil and pile-soil interfaces and mature research on the shear model of pile-soil interface [17,18], most previous studies on the shear model of anchor-soil interface utilized the relevant conclusions of the shear model of pile-soil interface. To investigate the shear characteristics of the anchor-soil interface, Chen et al [19] developed a tester that simulated the bonding characteristics of anchor-soil interface under various environmental conditions in batches and proposed a new shear model of anchor-soil interface.…”

Section: State Of the Artmentioning

confidence: 99%

Analytical Calculation on the Load - Displacement Curve of Grouted Soil Anchors

Yang¹,

Chen²,

Zhang³

et al. 2018

JESTR

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The load-displacement curve of anchors can be used as a basis for quality tests, and it is also important in the stability analysis of the combined supporting structure of anchors. Most of the existing analytical methods can only solve the partial pullout process of grouted soil anchors and obtain local load-displacement curves. To obtain a complete loaddisplacement curve, mechanical differential equations for the anchoring section in each stage were derived in this study based on a softening shear model of the anchor-soil interface and a load transfer model of the anchoring section. Combined with boundary conditions, the displacement, axial force, and shear stress distributions along the anchoring section and the analytical solutions for the load-displacement curve in the entire pullout process of anchors were obtained. The accuracy of the proposed method was verified by a pullout test on a foundation pit in Chongqing, China. Results show that a complete load-displacement curve is obtained with the proposed analytical method and a theoretical curve is consistent with a field pullout curve. The shear stress on the anchoring section is irregularly and non-uniformly distributed with a single peak. The load-displacement curve is influenced by the changes in parameters, such as anchorage length, anchorage radius, elastic modulus of the anchoring section, and residual shear coefficient. The present study accurately simulates the entire pullout process of anchors, determines their ultimate bearing capacity, obtains a complete load-displacement curve, and provides a theoretical basis for the quality evaluation and modelling analysis on grouted soil anchors.

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“…In the past, the ζ factor was devised under elastic mediums in non-slip analytical models, as described in Lo et al [8]. Recently, the limitations of non-slip analytical models have been discussed in Wang et al [5], Lo et al [8], Sheil and McCabe [9], Boonyatee and Lai [10], and slipping analytical models were recommended. In this study, the ζ factor in slipping analytical models is reviewed using finite element (FE) analyses of homogeneous and vertically inhomogeneous (Gibson soil, linear increase in the soil shear modulus (G) with depth) soils under the linear elastic and Mohr-Coulomb (MC, linear-elastic-perfectly-plastic) models.…”

Section: Introductionmentioning

confidence: 99%

A New Load-Transfer Factor to the Slipping Analytical Formulation in Axially Loaded Piles

Newell

et al. 2022

Geotechnics

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The load-transfer factor () in the concentric cylinder approach is often used in analytical formulation in axially loaded piles. The factor is a constant value (in a given pile slenderness ratio and soil condition) devised under the elastic and ‘pre-failure’ perfect pile–soil bonding conditions (a non-slip analytical model). Given most numerical methods have already considered the pile–soil slipping in the ‘pre-failure’ stage, the limitations of non-slip analytical models have recently been discussed, and slipping analytical models have been recommended. Therefore, this research aims to investigate the load-transfer factor in slipping analytical models. This paper reviews that the factor in slipping analytical models is only constant in linear elastic and some Gibson soil conditions. Beyond these conditions, the factor varies as the pile-head load increases in some cohesionless soils. Adopting the existing constant factor in slipping analytical models will deviate the load–displacement results, as supported by numerical results. Therefore, a new equation is proposed to the load-transfer factor, and a new analytical method is proposed by varying the load-transfer factor during loading for improvement. Results presented in this paper demonstrate improved load–displacement results.

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A non-linear load transfer method for determining the settlement of piles under vertical loading

Cited by 10 publications

References 23 publications

Base resistance of super-large and long piles in soft soil: performance of artificial neural network model and field implications

Base resistance of super-large and long piles in soft soil: performance of artificial neural network model and field implications

Analytical Calculation on the Load - Displacement Curve of Grouted Soil Anchors

A New Load-Transfer Factor to the Slipping Analytical Formulation in Axially Loaded Piles

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