Using the Pressuremeter Curve To Design Laterally Loaded Piles

Briaud, J-L; Smith, Trevor D.; Meyer, Barry J.

doi:10.4043/4501-ms

Cited by 31 publications

(14 citation statements)

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“…When scaling to large-diameter piles, a distinction must be made between a pile that behaves in an almost rigid fashion and one that is relatively flexible, since this affects the soil-pile behaviour (Briaud et al, 1984). A rigid pile rotates without flexing significantly, and develops a 'toe kick' under moment and lateral loading.…”

Section: Shortcomings Of Current Methodologymentioning

confidence: 99%

Response of stiff piles in sand to long-term cyclic lateral loading

LeBlanc¹,

Houlsby²,

Byrne³

2010

Géotechnique

476

273

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The driven monopile is currently the preferred foundation type for most offshore wind farms. While the static capacity of the monopile is important, a safe design must also address issues of accumulated rotation and changes in stiffness after long-term cyclic loading. Design guidance on this issue is limited. To address this, a series of laboratory tests were conducted where a stiff pile in drained sand was subjected to between 8000 and 60 000 cycles of combined moment and horizontal loading. A typical design for an offshore wind turbine monopile was used as a basis for the study, to ensure that pile dimensions and loading ranges were realistic. A complete non-dimensional framework for stiff piles in sand is presented, and applied to interpret the test results. The accumulated rotation was found to be dependent on relative density, and was strongly affected by the characteristics of the applied cyclic load. Particular loading characteristics were found to cause a significant increase in the accumulated rotation. The pile stiffness increased with number of cycles, which contrasts with the current methodology where static load-displacement curves are degraded to account for cyclic loading. Methods are presented to predict the change in stiffness and the accumulated rotation of a stiff pile due to long-term cyclic loading. The use of the methods developed is demonstrated for a typical fullscale monopile.KEYWORDS: laboratory tests; piles; repeated loading; sands; settlement; stiffness Le monopieu battu est actuellement le type de fondation préféré pour la plupart des parcs éoliens en mer. Bien que la capacité statique du monopieu soit importante, une conception sans danger doit également tenir compte des problèmes de la rotation accumulée et de variations dans la rigidité, à la suite d'efforts cycliques de longue durée. Les conseils et indications conceptuels relatifs à cette question étant limités, on a procédé à une série d'essais en laboratoire, dans le cadre desquels on a soumis un pieu rigide, enfoncé dans du sable drainé, à un nombre de cycles de moment de charge et de charges horizontales allant de 8000 à 60 000. On a utilisé, comme élément de base de cette étude, un modèle typique de monopieu pour éolienne en mer, afin d'assurer que les dimensions du pieu et les plages de charge étaient réalistes. Pour interpréter les résultats de cet essai, on présente et on applique un cadre non dimensionnel complet pour pieux rigides dans le sable. La rotation cumulée, qui s'est avérée tributaire du poids spécifique, était affectée dans une grande mesure par les caractéris-tiques de la charge cyclique appliquée. On s'est aperçu que certaines caractéristiques particulières de la charge engendraient une augmentaiton significative de la rotation cumulée. La rigidité du pieu augmentait avec le nombre de cycles, contrairement à la méthodologie actuelle, dans laquelle les courbes charge statique/déplace-ment sont dégradées pour tenir compte des charges cycliques. La communication présente des méthodes permettant de prédire les ...

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Section: Shortcomings Of Current Methodologymentioning

confidence: 99%

Response of stiff piles in sand to long-term cyclic lateral loading

LeBlanc¹,

Houlsby²,

Byrne³

2010

Géotechnique

476

273

View full text Add to dashboard Cite

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“…According to the author, this method is recommended to the design of drilled piers supporting transmission line structures. Briaud et al (1985) The total lateral reaction P to the deflection Y at a given depth is the sum of the frontal reaction Q and the tangential reaction F. As a result, the P-Y is the addition of the Q-Y curve and the F-Y curve. Carayannacon et al (1979) showed by finite element analysis that the contribution of the tangential reaction increases with slenderness of the pile section.…”

Section: Methods Of Dunand (1981)mentioning

confidence: 99%

Single piles under horizontal loads in sand: determination of P–Y curves from the prebored pressuremeter test

Bouafia

2006

Geotech Geol Eng

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Lateral load-deflection behaviour of single piles is often analysed in practice on the basis of methods of load-transfer P-Y curves. The paper is aimed at presenting the results of the interpretation of five full-scale horizontal loading tests of single instrumented piles in two sandy soils, in order to define the parameters of P-Y curves, namely the initial lateral reaction modulus and the lateral soil resistance, in correlation with the pressuremeter test parameters. P-Y curve parameters were found varying as a power of lateral pile/soil stiffness, on the basis of which hyperbolic P-Y curves in sand were proposed. The predictive capabilities of the proposed P-Y curves were assessed by predicting the soil/pile response in full-scale tests as well as in centrifuge tests and a very good agreement was found between the computed deflections and bending moments, and the measured ones. Small-sized database of fullscale pile loading tests in sand was built and a comparative study of some commonly used P-Y curve methods was undertaken. Moreover, it was shown that the load-deflection curves of these test piles may be normalised in a practical form for an approximate evaluation of pile deflection in a preliminary stage of pile design. At last, a parametric study undertaken on the basis of the proposed P-Y curves showed the significant influence of the lateral pile/soil stiffness on the nonlinear load-deflection response. Keywords Lateral loading test AE Lateral reaction modulus AE P-Y curves AE Pressuremeter test AE Sand AE Single pile List of symbols and units B diameter or frontal width of the pile (m) D embedded length of the pile (m) D e effective pile length (m) E elastic soil modulus (MPa) e excentricity of lateral load (m) E c characteristic soil modulus (MPa) E m first load pressuremeter modulus (MPa) E r reload pressuremeter modulus (MPa) E ti initial lateral reaction modulus (MPa) E p I p flexural pile stiffness (MN m 2 ) F tangential lateral reaction (kN/m) F l limit tangential lateral reaction or tangential lateral resistance (kN/m) G r pressuremeter shear modulus (G r = E r / [2(1 + m)]) (MPa) H lateral load applied on the pile top (kN) I d density index (%) K pile/soil compressibility K r lateral pile/soil stiffness L tangential dimension of the pile section (parallel to H) (m)

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“…no slurry. Among the previous studies of laterally loaded drilled shafts which have utilized soil pressure cells (Kasch et al 1977and Briaud et al 1983, 1985, the work by Bierschwale et al (1981) is of particular interest because the pressure cell data are well documented, and data for several azimuthal angles relative to the direction of loading are available.…”

Section: Previous Studies Of Interface Stressesmentioning

confidence: 99%

Interface Stresses between Soil and Large Diameter Drilled Shaft under Lateral Loading

Janoyan

Whelan

2004

GeoSupport 2004

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Results are presented of a field testing program for a full-scale, large diameter cast-in-drilled-hole (CIDH) shaft/column under large displacement cyclic lateral loading. The test shaft was extensively instrumented to enable high-precision section curvature measurements in addition to measurements of contact pressure at the soil-shaft interface around the shaft perimeter. Among the principal objectives of the testing was to characterize the soil-shaft interaction across a wide displacement range in order to gain insight into the adequacy of existing design guidelines (which are based principally on the testing of small diameter piles) for the large diameter shafts commonly used to support highway bridges. The component stresses of resistance and the effects of nonlinear soil resistance to relative displacements between the soil and shaft are presented.

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Using the Pressuremeter Curve To Design Laterally Loaded Piles

Cited by 31 publications

References 0 publications

Response of stiff piles in sand to long-term cyclic lateral loading

Response of stiff piles in sand to long-term cyclic lateral loading

Single piles under horizontal loads in sand: determination of P–Y curves from the prebored pressuremeter test

Interface Stresses between Soil and Large Diameter Drilled Shaft under Lateral Loading

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