322 results found
Dominguez-Quintans C, Quinteros VS, Carraro JAH, et al., Quality assessment of a new in-mould slurry deposition method for triaxial specimen reconstitution of clean and silty sands, 7th International Symposium on Deformation Characteristics of Geomaterials - IS Glasgow 2019
An innovative specimen reconstitution technique for sandy and silty soils that simulates underwater deposition is presented and evaluated. The technique is an upgraded version for triaxial testing of the well-established slurry deposition method. This novel setup integrates the reconstitution mould and the mixing tube into a single unit to avoid transferring the sample from the mixing tube to the mould. This subtle, but critical, modification enables reconstitution of very loose specimens as sample transfer disturbance, which can be significant, is eliminated. The quality of specimens prepared by the new reconstitution method was assessed by experiments on a clean sand from the UK (Ham River sand) and a silty sand from Norway (Øysand). The method, as any slurry-based procedure, is capable of producing homogeneous specimens with high initial degree of saturation, even in the absence of back pressure. The procedure is shown to be suitable for sands with or without fines. Moreover, the new method is able to achieve a wide range of initial void ratios, from very loose to very dense, without imposing any particle crushing in the latter case.
Taborda D, Zdravkovic L, Potts DM, et al., Finite element modelling of laterally loaded piles in a dense marine sand at Dunkirk, Géotechnique, ISSN: 0016-8505
Byrne BW, Burd HJ, Gavin KG, et al., 2019, PISA: Recent developments in offshore wind turbine monopile design, Pages: 350-355, ISSN: 2366-2557
© Springer Nature Singapore Pte Ltd. 2019. This paper provides a brief overview of the Pile Soil Analysis (PISA) project, recently completed in the UK. The research was aimed at developing new design methods for laterally loaded monopile foundations, such as those supporting offshore wind turbine structures. The paper first describes the background to the project and briefly outlines the key research elements completed. The paper concludes with a brief description of the anticipated impact of the work and describes initiatives that have followed since.
Zdravkovic L, Taborda D, Potts D, et al., Finite element modelling of laterally loaded piles in a stiff glacial clay till at Cowden, Géotechnique, ISSN: 0016-8505
The PISA project was a combined field testing/numerical modelling study with the aim ofdevelopingimproved design procedures for large diameter piles subjected to lateral loading. This paper describes the development ofa three-dimensional finite elementmodel for the medium-scale pile tests that were conducted in Cowden tillas part of the PISA work.The paper places particular emphasis on the consistent interpretation of the soil data determined from the available field and laboratory information.An enhancedversion of the modified Cam clay model was employedin the numerical analyses, featuring a non-linear Hvorslevsurface, a generalised shape for the yield and plastic potential surfaces in the deviatoric planeand a non-linear formulation for the elastic shear modulus.Three-dimensional finite element analyses were performed prior to the field tests.Excellent agreement between the measured and simulated behaviourfora range of pile geometrieswas observed, demonstrating the accuracy of the numerical model and the adequacy of the calibration process for theconstitutive model.The developed numerical modelconfirmed the premise of the PISA design method that site-specific ground characterisation and advanced numerical modelling candirectly facilitate the development of additionalsoil reaction curves for use in new design models for laterally loaded piles in a stiff clay till.
Buckley RM, Jardine RJ, Kontoe S, et al., 2018, Effective stress regime around a jacked steel pile during installation ageing and load testing in chalk, CANADIAN GEOTECHNICAL JOURNAL, Vol: 55, Pages: 1577-1591, ISSN: 0008-3674
Byrne B, McAdam RA, Burd HJ, et al., Monotonic laterally loaded pile testing in a stiff glacial clay till at Cowden, Géotechnique, ISSN: 0016-8505
This paper describes theresults obtained from a field testing campaign on laterally-loaded monopiles conducted at Cowden, UK, where the soil consists principally of aheavilyoverconsolidatedglacial till. These tests formed part of the PISA projecton the development of improved design methods for monopile foundations for offshore wind turbines. Results obtained for monotonic loading tests on piles of three different diameters (0.273m, 0.762m and 2.0m) are presented. The piles had length-to-diameter ratios (L/D) of between 3 and 10. Thetests includedthe application of monotonic loading incorporating periods of constant load to investigate creep effects,and investigations on the influence of loading rate. Data are presented on measured bending moments and inclinations induced in the piles. Inferred data on lateral displacements of the embedded section of the pilesare determined usingan optimisedstructural model. Thesefield data support the developmentof a new 1D modelling approach forthe design of monopile foundations for offshore wind turbines.They also form a unique database of field measurements in an overconsolidated clay, from lateral loading of piles at a vertical distance abovethe ground surface.
Zdravkovic L, Jardine R, Taborda DMG, et al., Ground characterisation for PISA pile testing and analysis, Géotechnique, ISSN: 0016-8505
This paper is the first of a set of linked publications on the PISA Joint Industry Research Project, which was concerned with the development of improved design methods for monopile foundations in offshore wind applications. PISA involved large-scale pile tests in overconsolidated glacial till at Cowden, north-east England,and in dense normally consolidated marine sand at Dunkirk, northern France. The paper presents the characterisationof the two sites, whichwas crucial to the design of the field experiments and advanced numerical modelling of the pile-soil interactions. The studies described, which had to be completed at an early stage of the PISA project, added new laboratory and field campaignsto historic investigations at both sites.Theyenabledanaccurate description ofsoilbehaviour from small strains to ultimate statesto be derived, allowing analyses to be undertaken that captured both the serviceability and limit statebehaviour of the test monopiles.
Burd HJ, Beuckelaers WJAP, Byrne BW, et al., New data analysis methods for instrumented medium scale monopile field tests, Géotechnique, ISSN: 0016-8505
The PISA Joint Industry Research Project was concerned with the development of improved design methods for monopile foundations in offshore wind applications. PISA involved large-scale pile tests in overconsolidated glacial till at Cowden, north-east England, andin dense normally consolidated marine sand at Dunkirk, northern France. This paper describes the experimental set up for pile testing, with unique features of load-application mechanisms and built-in fibre optic strain gauges.New procedures are describedfor the interpretation of pile loading data, and specifically for providing precise interpretation of pile displacements.
McAdam RA, Byrne BW, Houlsby GT, et al., Monotonic lateral loaded pile testing in a dense marine sand at Dunkirk, Géotechnique, ISSN: 0016-8505
Theresults obtained from a field testing campaignon laterally-loaded monopiles,conducted ata dense sand site inDunkirk, Northern Franceare described.These tests formed part of thePISA projecton the development of improved design methods for monopile foundations for offshore wind turbines. Results obtained frommonotonic loading tests on piles of three different diameters (0.273m, 0.762m and 2.0m) are presented. The piles had aspectratios (L/D) of between 3 and 10. Thetests consisted principally of the application of monotonic loads,incorporating periods of held constant load to investigate creep effects.The influence of loading ratewas also investigated. Data are presented on the overall load displacement behaviour of each of the test piles. Measured data on bending moments and inclinations induced in the pilesare also provided.Inferences are made forthe displacements in the embedded length of the piles. Thesefield data will support the development of a new 1D modelling approach forthe design of monopile foundations for offshore wind turbines.They also form a unique database of field measurements in a dense sand, from lateral loading of piles at a vertical distance abovethe ground surface.
Altuhafi FN, Jardine RJ, Georgiannou VN, et al., 2018, Effects of particle breakage and stress reversal on the behaviour of sand around displacement piles, GEOTECHNIQUE, Vol: 68, Pages: 546-555, ISSN: 0016-8505
Buckley RM, Jardine RJ, Kontoe S, et al., 2018, Ageing and cyclic behaviour of axially loaded piles driven in chalk, GEOTECHNIQUE, Vol: 68, Pages: 146-161, ISSN: 0016-8505
Jardine RJ, Yang ZX, 2018, Joint research into the behaviour of driven piles, Pages: 961-972, ISSN: 1866-8755
© Springer Nature Switzerland AG 2018. Large driven piles are used widely in both onshore and offshore construction. Predicting their limiting capacities and load-displacement behaviour under a range of static and cyclic, axial, lateral and moment loading conditions is critical to many engineering applications. This paper reviews relevant recent joint research by groups at Imperial College London (ICL) and Zhejiang University China (ZJU). Two tracks of enquiry are outlined: (i) assembling and analysing a major and open database of high quality load tests conducted on industrial scale piles at well characterised sites; and (ii) modelling the effective stress regime developed around piles driven in sands. Both avenues of research are vital to enabling scientifically well-founded and yet industrially credible improvements to practical pile design methods. The scope of future joint research is also outlined.
Guo L, Cai Y, Jardine RJ, et al., 2018, Undrained behaviour of intact soft clay under cyclic paths that match vehicle loading conditions, CANADIAN GEOTECHNICAL JOURNAL, Vol: 55, Pages: 90-106, ISSN: 0008-3674
Burd HJ, Byrne BW, McAdam R, et al., 2017, Foundation Design of Offshore Wind Structures, TC209 Workshop on Foundation Design of Offshore Wind Structures, 19th International Conference on Soil Mechanics and Geotechnical Engineering
This paper describes the outcome of a recently completed research project – known as PISA – on the development of a new process for the design of monopile foundations for offshore wind turbine support structures. The PISA research was concerned with the use of field testing and three-dimensional (3D) finite element analysis to develop and calibrate a new one-dimensional (1D) design model. The resulting 1D design model is based on the same basic assumptions and principles that underlie the current p-y method, but the method is extended to include additional components of soil reaction acting on the pile, and enhanced to provide an improved representation of the soil-pile interaction behaviour. Mathematical functions – termed ‘soil reaction curves’ – are employed to represent the individual soil reaction components in the 1D design model. Values of the parameters needed to specify the soil reaction curves for a particular design scenario are determined using a set of 3D finite element calibration analyses. The PISA research was focused on two particular soil types (overconsolidated clay till and dense sand) that commonly occur in north European coastal waters. The current paper provides an overview of the field testing and 3D modelling aspects of the project, and then focuses on the development, calibration and application of the PISA design approach for monopiles in dense sand.
Buckley R, Kontoe S, Jardine R, et al., 2017, Common pitfalls of pile driving resistance analysis - A case study of the Wikinger offshore windfarm, 978-0-906940-57-0, Publisher: Society for Underwater Technology, Pages: 1246-1253
Buckley R, Jardine R, Kontoe S, et al., 2017, Field investigations into the axial loading response of displacement piles in chalk, Proceedings of the 8th International Conference on Offshore Site Investigation and Geotechnics: Smarter Solutions for Future Offshore Developments, Publisher: Th e Society for Underwater Technology, Pages: 1178-1185
Byrne BW, McAdam RA, Burd H, et al., 2017, PISA: new design methods for offshore wind turbine monopiles, Proceedings of the Society for Underwater Technology Offshore Site Investigation and Geotechnics 8th International Conference on “Smarter Solutions for Future Offshore Developments"
Brosse AM, Jardine RJ, Nishimura S, 2017, The undrained shear strength anisotropy of four Jurassic to Eocene stiff clays, GEOTECHNIQUE, Vol: 67, Pages: 653-671, ISSN: 0016-8505
Cai YQ, Guo L, Jardine RJ, et al., 2017, Stress-strain response of soft clay to traffic loading, GEOTECHNIQUE, Vol: 67, Pages: 446-451, ISSN: 0016-8505
Brosse A, Jardine RJ, Nishimura S, 2017, Undrained stiffness anisotropy from hollow cylinder experiments on four Eocene-to-Jurassic UK stiff clays, CANADIAN GEOTECHNICAL JOURNAL, Vol: 54, Pages: 313-332, ISSN: 0008-3674
Brosse A, Hosseini Kamal R, Jardine RJ, et al., 2017, The shear stiffness characteristics of four Eocene-to-Jurassic UK stiff clays, Géotechnique, Vol: 67, Pages: 242-259, ISSN: 0016-8505
Yang ZX, Guo WB, Jardine RJ, et al., 2017, Design method reliability assessment from an extended database of axial load tests on piles driven in sand, CANADIAN GEOTECHNICAL JOURNAL, Vol: 54, Pages: 59-74, ISSN: 0008-3674
Liu T, Aghakouchak A, Taborda DMG, et al., 2017, Advanced laboratory characterization of a fine marine sand from Dunkirk, France, Pages: 439-442
Dense fine marine sand is encountered at the Dunkirk ZIP Les Huttes test site located in northern France that has been employed extensively for research into pile behaviour. Laboratory testing of the sand is required to fully characterise site conditions and determine parameter inputs for analysing the field pile experiments. This paper summarises some of the comprehensive laboratory testing programmes undertaken to investigate the sand’s mechanical behaviour, including stress-strain relationships, stiffness and strength anisotropy, cyclic behaviour, and interface shear properties. The paper first reviews the site’s geotechnical conditions and their potential variations over time. The stringent laboratory requirements that are necessary for the accurate measurement of shear stiffness, strength, and creep strains are then discussed, before presenting illustrative results regarding the sand’s small strain stiffness and time-dependent behaviour. The importance of reproducing site conditions and stress states are also addressed in relation to integrating the laboratory research with field observations and analyses of both recent and historical piling experiments at the Dunkirk test site.
Jardine RJ, Brosse A, Coop MR, et al., 2015, Shear strength and stiffness anisotropy of geologically aged stiff clays., International Symposium on Deformation Behaviour of Geomaterials, Publisher: IOS Press, Pages: 156-191
This paper considers the deformation behaviour of four geologically aged, medium-plasticity, heavily overconsolidated stiff clays that affect a broad swathe of infrastructure projects in the SE of the United Kingdom. Static triaxial and hollow cylinder stress path experiments on high quality samples are examined along with dynamic multi-axial bender element and resonant-column measurements. Patterns of undrained shear strength anisotropy are revealed that are governed by the clays' meso and micro-structures. The clays are brittle in shear and their stiffness characteristics are shown to be markedly anisotropic, highly non-linear and pressure dependent. The results obtained have many implications for practical geotechnical engineering.
Aghakouchakn A, Sim WW, Jardine RJ, 2015, Stress-path laboratory tests to characterise the cyclic behaviour of piles driven in sands, SOILS AND FOUNDATIONS, Vol: 55, Pages: 917-928, ISSN: 0038-0806
Yang ZX, Jardine RJ, Zhu BT, et al., 2015, Closure to "Stresses Developed around Displacement Piles Penetration in Sand" by Z. X. Yang, R. J. Jardine, B. T. Zhu, and S. Rimoy, JOURNAL OF GEOTECHNICAL AND GEOENVIRONMENTAL ENGINEERING, Vol: 141, ISSN: 1090-0241
Yang ZX, Guo WB, Zha FS, et al., 2015, Field Behavior of Driven Prestressed High-Strength Concrete Piles in Sandy Soils, Journal of Geotechnical and Geoenvironmental Engineering, Vol: 141, ISSN: 1943-5606
Driven piles are used widely both offshore and onshore. However, accurate axial capacity and load-displacement prediction is difficult at sand-dominated sites, and offshore practice is moving towards cone penetration test (CPT) based design methods developed from instrumented pile research and database studies. However, onshore use of these methods remains limited; there is a paucity of high quality case histories to assess their potential benefits clearly, and application in layered profiles may be uncertain. This paper presents new tests on prestressed concrete (PHC) pipe piles driven in sands for a major new Yangtze River bridge project in China, assessing the performance of the ‘new CPT’ and conventional capacity approaches, considering the influence of weak sublayers on base resistance and noting the marked changes in shaft capacity that apply over time.
Doherty P, Igoe D, Murphy G, et al., 2015, Field validation of fibre Bragg grating sensors for measuring strain on driven steel piles, GEOTECHNIQUE LETTERS, Vol: 5, Pages: 74-79, ISSN: 2049-825X
Yang ZX, Jardine RJ, Guo WB, et al., 2015, A new and openly accessible database of tests on piles driven in sands, Géotechnique Letters, Vol: 5, Pages: 12-20, ISSN: 2045-2543
Jardine RJ, Thomsen NV, Mygind M, et al., 2015, Axial capacity design practice for North European wind-turbine projects, Pages: 581-586
© 2015 Taylor & Francis Group, London. Improving foundation design is central to the offshore wind industry developing deeper water sites. This paper reviews the technical and regulatory difficulties for design of axially loaded piles to German offshore windfarm projects. It is argued that moving towards reliable forward predictive pile design methods and away from ‘dynamic proving tests’ will be vital to reducing unnecessarily high material and installation costs, installation risks and disturbance to marine mammals. Steps are outlined to implement such a change either in combination with regional or international load and resistance factors.
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