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Publications (40)
Robust design of offshore wind turbine foundations requires that the ultimate capacity is acceptable. In addition the accumulated deformations over 25 years of operational life, typically 10 8 cycles, must also be limited. This paper outlines a numerical method for modelling the response of monopiles to monotonic and cyclic lateral loading to very...
The PISA design model is a procedure for the analysis of monopile foundations for offshore wind turbine applications. This design model has been previously calibrated for homogeneous soils; this paper extends the modelling approach to the analysis of monopiles installed at sites where the soil profile is layered. The paper describes a computational...
This paper reports the use of optical fiber Bragg-grating (FBG) sensors to monitor the stress waves generated below ground during pile driving, combined with measurements using conventional pile driving analyzer (PDA) sensors mounted at the pile head. Fourteen tubular steel piles with a diameter of 508 mm and embedded length-to-diameter ratios of 6...
Scour erosion processes can occur at seabed level around offshore wind turbine monopile foundations. These scour processes are often especially severe at sites where mobile sediments, such as sands, are present in the superficial seabed soils. Loss of local soil support to the monopile, caused by scour erosion, can lead to significant changes in th...
This paper describes a one-dimensional (1D) computational model for the analysis and design of laterally loaded monopile foundations for offshore wind turbine applications. The model represents the monopile as an embedded beam and specially formulated functions, referred to as soil reaction curves, are employed to represent the various components o...
Offshore wind turbines in shallow coastal waters are typically supported on monopile foundations. Although three-dimensional (3D) finite-element methods are available for the design of monopiles in this context, much of the routine design work is currently conducted using simplified one-dimensional (1D) models based on the p–y method. The p–y metho...
Chalk is present under large areas of NW Europe as a low-density, porous, weak carbonate rock. Large numbers of offshore wind turbines, bridges and port facilities rely on piles driven in chalk. Current European practice assumes ultimate shaft resistances that appear low in comparison with the Chalk’s unconfined compression strength and CPT cone re...
The paper presents the development of a three-dimensional finite-element model for pile tests in dense Dunkirk sand, conducted as part of the PISA project. The project was aimed at developing improved design methods for laterally loaded piles, as used in offshore wind turbine foundations. The importance of the consistent and integrated interpretati...
The PISA project was a combined field testing/numerical modelling study with the aim of developing improved design procedures for large-diameter piles subjected to lateral loading. This paper describes the development of a three-dimensional finite-element model for the medium-scale pile tests that were conducted in Cowden till as part of the PISA w...
The results obtained from a field testing campaign on laterally loaded monopiles, conducted at a dense sand site in Dunkirk, northern France are described. These tests formed part of the PISA project on the development of improved design methods for monopile foundations for offshore wind turbines. Results obtained from monotonic loading tests on pi...
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, and in dense, normally consolidated marine sand at Dunkirk, northern France. This paper de...
This paper describes the results obtained from a field testing campaign on laterally loaded monopiles conducted at Cowden, UK, where the soil consists principally of a heavily overconsolidated glacial till. These tests formed part of the PISA project on the development of improved design methods for monopile foundations for offshore wind turbines....
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 c...
There are two approaches to extracting power from tides — either turbines are placed in areas of strong flows or turbines are placed in barrages enabling the two sides of the barrage to be closed off and a head to build up across the barrage. Both of these energy extraction approaches will have a significant back effect on the flow, and it is vital...
This paper provides an overview of the PISA design model recently developed for laterally loaded offshore wind turbine monopiles through a major European joint-industry academic research project, the PISA Project. The focus was on large diameter, relatively rigid piles, with low length to diameter (L/D) ratios, embedded in clay soils of different s...
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 ke...
This paper provides a summary of the PIle Soil Analysis (PISA) project, completed in the UK during the period 2013 to 2018. The research led to the development of a new, computationally efficient, one dimensional design model for laterally loaded monopile foundations, particularly for offshore wind turbine support structures. The current form of th...
The recently-completed PISA (PIle Soil Analysis) research project aimed to improve the design of monopile foundations for offshore wind turbines (OWT), focusing on laterally-loaded monopiles with length-to-diameter (L/D) ratios between 2 and 6. The project resulted in a novel one-dimensional (1D) design model which overcomes certain limitations in...
![Fig. 2 Idealised clay till [11] and the corresponding PLAXIS MoDeTo...](profile/Stavros-Panagoulias/publication/328342925/figure/fig1/AS:682743079911424@1539790043012/dealised-clay-till-11-and-the-corresponding-PLAXIS-MoDeTo-profiles-for-the-lateral_Q320.jpg)
The recently-completed PISA (PIle Soil Analysis) research project aimed to improve the design of monopile foundations for offshore wind turbines (OWT), focusing on laterally-loaded monopiles with length-to-diameter (L/D) ratios between 2 and 6. The project resulted in a novel one-dimensional (1D) design model which overcomes certain limitations in...
Local and global scour around offshore wind turbine monopile foundations can lead to a
reduction in system stiffness, and a consequential drop in the natural frequency of the combined monopiletower-
nacelle structure. If unchecked this could lead to operational problems such as accelerated fatigue
damage and de-rating or decommissioning of the turb...
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...
In the PISA project, over 28 pile test are performed to investigate the behaviour of monopile foundations. These test piles are instrumented with inclinometers and displacement transducers above ground; a subset of the piles are instrumented below ground with inclinometers, extensometers and strain gauges. To analyse the data, processing tools are...
Improved design of laterally loaded monopiles is central to the development of current and future generation offshore wind farms. Previously established design methods have demonstrable shortcomings requiring new ideas and approaches to be developed, specific for the offshore wind turbine sector. The Pile Soil Analysis (PISA) Project, established i...
In recent years, fibre Bragg grating (FBG) sensors have emerged as a relatively new strain sensing technology for civil engineering applications. This paper presents a field trial to assess the feasibility of using FBG sensor arrays to measure strain in driven steel piles. Two FBG arrays were installed in grooves within the wall of an open-ended st...
Offshore wind turbines are typically founded on single large diameter piles, termed monopiles. Pile diameters of between 5m and 6m are routinely used, with diameters of up to 10m, or more, being considered for future designs. There are concerns that current design approaches, such as the p-y method, which were developed for piles with a relatively...
There is currently a significant focus on developing offshore wind power in the UK and Europe. The most common foundation type for wind turbines is a single large diameter pile, termed a monopile, on which the turbine is located. As the diameter of such piles is envisaged to increase in future installations, there are concerns that current design m...
This paper is the third of three, which describe the procedures and results for a set of experiments on various configurations of the Transverse Horizontal Axis Water Turbine (THAWT), which is a horizontally orientated variant of the Darrieus cross-flow turbine. Tests were conducted in the combined wind, wave and current tank at Newcastle Universit...
This paper is the second of three, which outline the procedures and results for a set of experiments on various configurations of the Transverse Horizontal Axis Water Turbine (THAWT), which is a horizontally orientated variant of the Darrieus cross-flow turbine. Tests were conducted in the combined wind, wave and current tank at Newcastle Universit...
This paper is the first of three, which outline the procedures and results for a set of experiments carried out on various configurations of the Transverse Horizontal Axis Water Turbine (THAWT), which is a horizontally orientated variant of the Darrieus cross-flow turbine. Tests were conducted in the combined wind, wave and current tank at Newcastl...
Tidal turbine blades are smaller than wind turbine blades yet carry similar bending moments. This provides a structural challenge and limits how thin the blades can be made, which subsequently affects the hydrodynamic performance of the rotor. Thinner blades generally offer higher performance but require thicker laminates hence are more expensive t...
Model tests on two designs of 0.5m diameter transverse flow turbine are described. Measurements were made relevant to both the hydrodynamic and structural performance of the turbines, and a variety of conditions were explored (including flow depth, upstream velocity, flow direction, blade pitch, turbine solidity). This paper concentrates particular...
This study outlines the procedures and results for a set of experiments on the transverse horizontal axis water turbine (THAWT), which is a variant of a Darrieus turbine. Testing of a 1/20th scale device was conducted in the combined wind, wave and current tank at Newcastle University. Flow depth and velocity were varied over a range of realistic F...
This paper outlines the procedures and preliminary results for a set of experiments on the Transverse Horizontal Axis Water Turbine (THAWT), which is a variant of a Darrieus turbine. Testing of a 1/20th scale device was conducted in the combined wind, wave and current tank at Newcastle University. Flow depth and velocity were varied over a range of...
Projects
Projects (5)
The ALPACA project started in October 2017 with funding from EPSRC (£1.38m) and Industry (£390k; contributions from Atkins, Cathie Associates, DNVGL, Fugro, GCG, Iberdrola/SPR, Innogy, LEMS, ØRSTED, Siemens, Statoil) aiming to develop new driven pile design guidance for chalk sites through a comprehensive programme of high quality field tests, advanced laboratory testing, rigorous analysis and synthesis with other case history data. The Academic Work Group comprises academics and researchers from Imperial College London (project lead) and Oxford University, with the key aim to develop design procedures that overcome, for chalk, the current shortfalls in knowledge regarding pile driving, ageing, static and cyclic response under axial and lateral loading. The research has applications with offshore wind turbines and oil platforms as well as port, bridge and other works.
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