Róisín BuckleyUniversity of Glasgow | UofG · School of Engineering
Róisín Buckley
BE (Hons) MSc PhD DIC MIEI
About
29
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Introduction
Publications
Publications (29)
This paper reports a programme of static and cyclic loading tests on seven open steel tubes driven in low to medium density chalk at a well characterised test site, describing their response to driving, ageing in-situ and loading under both static and cyclic conditions. Back analysis of dynamic monitoring identifies the distributions of notably low...
This paper reports experiments with 102mm diameter closed-ended instrumented Imperial College Piles (ICPs) jacked into low to medium density chalk at a well characterised UK test site. The 'ICP' instruments allowed the effective stress regime surrounding the pile shaft to be tracked during pile installation, equalisation periods of up to 2.5 months...
This paper describes and interprets tests on piles driven through glacial tills and chalk at a Baltic Sea windfarm, covering an advance trial campaign and later production piling. The trials involved six instrumented 1.37m diameter steel open-ended tubes driven in water depths up to 42m. Three piles were tested statically, with dynamic re-strike te...
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...
The installation and loading of steel piles driven in sands modifies both the piles' surface topography and the characteristics of the granular materials present adjacent to the pile shaft. Large-displacement ring shear interface tests incorporating pre-conditioning stages are capable of reproducing such physical processes in the laboratory and can...
Comprehensive field investigations into the axial cyclic loading behaviour of open-steel pipe piles driven and aged in low-to-medium density chalk identify the conditions under which behaviour is stable, unstable or metastable. Post-cycling monotonic tests confirmed that stable cycling enhanced pile capacity marginally, while unstable cases suffere...
This paper describes research into the poorly understood axial behaviour of piles driven in chalk. Comprehensive dynamic and monotonic axial testing on 27, mostly instrumented, piles undertaken for the ALPACA Joint Industry Projects is reported and interpreted covering: diameters between 139mm and 1.8m; lengths from 3 to 18m; different pile materia...
Several methodologies to predict the static soil resistance to driving (SRD) available in the literature have found wide use in the offshore industry over the last decades. These range from simple methods that require few soil strength parameters to more advanced semi-empirical methods that correlate the driving resistance to cone penetration test...
Low-to-medium density chalk at St Nicholas at Wade, UK, is characterised by intensive testing to inform the interpretation of axial and lateral tests on driven piles. The chalk de-structures when taken to large strains, especially under dynamic loading, leading to remarkably high pore pressures beneath penetrating CPT and driven pile tips, weak put...
Low-to-medium density chalk can be de-structured to soft putty by high-pressure compression, dynamic impact or large-strain repetitive shearing. These process all occur during pile driving and affect subsequent static and cyclic load-carrying capacities. This paper reports undrained triaxial experiments on de-structured chalk, which shows distinctl...
Chalk, a soft, white, variable, high porosity, rock has been the focus of recent research into pile behaviour following the rapid expansion of offshore windfarms in Northern Europe and the advancement of other major infrastructure projects in areas where foundations are installed in chalk. An overview of recent in-situ testing (cone penetration tes...
Pile driving in low to medium density chalk is subject to significant uncertainty. Predictions of Chalk Resistance to Driving (CRD) often vary considerably from field driving behaviour, with both pile refusals and free falls under zero load being reported. However, recent field studies have led to better understanding of the processes which control...
Current axial capacity design methods for piles driven in chalk are known to be unreliable, in particular where low-medium density material is encountered. The primary complexities associated with using driven pre-formed displacement piles to withstand predominantly axial loading include (i) determining their installation resistance (ii) assessing...
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 behaviour of driven piles in chalk is poorly understood; their installation resistance, setup characteristics and response to cyclic and static loading all warrant further investigation. Current axial capacity design methods have poor reliability, particularly in low-medium density chalk. This paper gives an overview of research which combined...
Chalk, a soft fine-grained Cretaceous limestone, is encountered across northern Europe where recent offshore windfarm, oil, gas and onshore developments have called for better foundation design methods, particularly for driven piles whose shaft capacities are controlled by an effective stress Coulomb interface failure criterion. Interface type and...
Driving resistance is difficult to predict in chalk strata, with both pile free-fall self-weight ‘runs’ and refusals being reported. Axial capacity is also highly uncertain after driving. This paper reviews recent research that has explored these topics. Programmes of onshore tests and novel, high-value offshore, experiments involving static, dynam...
Substantial recent investment in offshore wind energy developments and other foundation projects in chalk dominated locations has created an urgent need for a better understanding of how driven piles behave in this variable and unpredictable material. Pile driving in chalk is known to create a remoulded zone of chalk ‘putty’ around the pile which m...
The British Geotechnical Association (BGA) with support from the Engineering Group of the Geological Society (EGGS) will be hosting a major two-day international conference on Engineering in Chalk on 17th and 18th September 2018 at Imperial College in London.
The last major conference on Chalk was held almost 30 years ago in 1989 in Brighton. Sin...
Offshore developments in Northern Europe often encounter chalk, a highly variable soft rock. The designers of foundation piles driven in such strata can face considerable uncertainty regarding (i) the axial resistances developed during installation, (ii) those available after consolidation and ageing and (iii) the response to cyclic axial loading....
Pile driving resistance analyses are often performed to provide indicative information on potential axial static capacity. This involves a well-established approach, commonly known as signal matching, in which dynamic measurements made during impact driving are related to estimates of shaft and base resistance through wave propagation theory. The d...
Projects
Projects (3)
The goal of this project is to improve efficiency and cost effectiveness of piles driven in soft rocks to support structures in the offshore environment. To achieve this goal, rigorous numerical and experimental modelling will be employed and the following objectives are planned:
1. improve pile drivability assessment for open-ended piles
2. quantify the influence of installation on long-term in-service performance offshore wind turbines (OWT)
3. develop practical tools to incorporate these effects within engineering analysis and design.
There have been a lot of studies in clay and sand but there are other geomaterials which are quite widespread and pose a challenge to the offshore industry.
The central research activities of the ICE-PICK include experimental and numerical simulations of pile installation and subsequent long-term in service environmental cyclic loading. These results will be used to develop an industry-applicable analytical macro-element-based pile-soil-reaction model for reliable pile design equipped to capture installation effects on the long-term cyclic loading performance. Existing field test data on monopiles in chalk will be used to validate key elements of the numerical and analytical approaches (pile drivability, post installation set-up and cyclic degradation) at the engineering scale
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.
The overall project aims are to provide more secure and cost-effective turbine support structures for windfarms installed in difficult ground offshore Northern Europe, giving particular attention to Chalk dominated sites. In particular:
(i) To understand the low resistances observed during driving,
(ii) Systematically quantify ‘friction fatigue’ during installation and set-up over pauses of several months and
(iii) Assess axial response under one-way cycling.
