ORCID Profile
0000-0002-5442-0014
Current Organisation
University of Melbourne
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Civil Engineering | Civil Geotechnical Engineering |
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in Engineering | Wind Energy | Oil and Gas Extraction | Wave Energy | Geothermal Exploration | Civil Construction Design | Energy Exploration not elsewhere classified
Related Links
Publications
Free-Falling Penetrometers: A Laboratory Investigation in Clay
Publisher: American Society of Civil Engineers (ASCE)
Date: 2014
Recent Advances in Anchor Design for Floating Structures
Publisher: International Society of Offshore and Polar Engineers
Date: 03-2017
Consolidation effects on monotonic and cyclic capacity of plate anchors in sand
Publisher: Thomas Telford Ltd.
Date: 08-2020
Abstract: This study investigated the change in monotonic and cyclic capacity of a plate anchor across different degrees of consolidation in dense sand. To quantify the effect of consolidation on anchor capacity, a framework is introduced and validated using centrifuge model anchor test data. The centrifuge tests considered a rectangular plate loaded at varying rates in dense sand, under both monotonic and irregular cyclic conditions, at a fixed embedment depth and with a horizontal load inclination (at the seabed). In order to vary from drained to undrained conditions, the sand was saturated using both water and a viscous pore fluid with viscosity approximately 700 times higher than water. The anchor's ultimate monotonic capacity in dense sand increased by up to 173% as the consolidation response evolved from drained to undrained with generation of dilation-induced suction. This increase in capacity across the consolidation regime can be adequately quantified using the proposed framework however, uncertainty arises in achieving the theoretical undrained capacity. Both drained and undrained irregular cyclic loading resulted in anchor capacity increases of up to 33%, attributed to soil volume changes associated with cyclic densification under drained cyclic loading and excess pore pressure dissipation under undrained cyclic loading.
Towards a simple and reliable method for calculating the uplift capacity of plate anchors in sand
Publisher: Canadian Science Publishing
Date: 09-2020
Abstract: This paper investigates the uplift capacity of horizontal plate anchors in sand through finite element analyses and centrifuge experiments. The finite element simulations adopt a sophisticated bounding surface plasticity model that accounts for stress- and density-dependent behaviour, as well as loading- and fabric-related anisotropic effects in sands. Failure mechanisms at peak anchor capacity show that failure occurs progressively, with a marked decrease in mobilised friction angle within the shear bands close to the anchor edge. Numerical simulations of a large set of centrifuge experiments on rectangular, strip, and circular plates at different relative densities and stress levels are in good agreement for dense conditions, but perform more poorly for loose conditions due mainly to the open cone yield surface in the bounding surface model. Equivalent comparisons with current limit equilibrium methods highlight the challenges in direct application of element-level strength equations. Finally, the paper proposes a modified limit equilibrium solution based on a “rigid-block” failure mechanism extending to the soil surface, but with anchor factors that encompass the results from the finite element simulations. The modified solution provides a higher level of agreement with results from a large database of plate and pipeline test data than existing limit equilibrium methods.
Discussion: Measuring the plastic limit of fine soils: an experimental study
Publisher: Thomas Telford Ltd.
Date: 02-2016
Dynamic Analysis of Free-Falling Penetrometers in Soil Deposits
Publisher: American Society of Civil Engineers
Date: 15-02-2010
DOI: 10.1061/41095(365)3
Numerical and analytical investigation on inclined plate anchors in sand
Publisher: Elsevier BV
Date: 02-2023
A review of anchor technology for floating renewable energy devices and key design considerations
Publisher: CRC Press
Date: 14-05-2015
DOI: 10.1201/B18442-127
Drained cyclic capacity of plate anchors in dense sand: Experimental and theoretical observations
Publisher: Thomas Telford Ltd.
Date: 02-2015
Abstract: This paper provides experimental evidence that shows that the drained cyclic capacity of a plate anchor in dry dense sand may be higher than the equivalent monotonic capacity. The experimental data show that when cyclic loading is low relative to the monotonic capacity, increases in the eventual capacity are observed when the magnitudes of the cyclic loads are closer to the monotonic capacity, no increases in capacity are observed. These responses are explained in the paper using an elasto-plastic macro-element model extended with expandable bounding and memory surfaces that address the increase in strength or stiffness caused by changes in soil density and fabric when the anchor is subject to cyclic loading in dense sand.
Use of a bounding surface model in predicting element tests and capacity in boundary value problems
Publisher: Canadian Science Publishing
Date: 06-2020
Abstract: The paper examines the merit of a bounding surface plasticity model at both element and system level. The governing equations are based essentially on the parent bounding surface plasticity model reported by Dafalias and Manzari in 2004 with some simple yet practical changes to enable realistic predictions for monotonic loading along different load paths. This is achieved by scaling the influence of the state parameter based on a normalised measure of anisotropy, thus leading to suitable change in dilatancy and plastic modulus for different loading directions. The paper presents a simple optimisation technique for calibrating the model parameters, providing an objective approach to reduce the uncertainties in parameter determination that leads to good agreement with responses measured in drained and undrained triaxial tests. The model has also been implemented for the boundary value problem of a buried circular plate anchor and a surface circular footing. Comparisons of the simulated responses with those measured in centrifuge tests demonstrate the potential of the model, whilst also pointing to the challenges in capturing the global response at all strain levels, even for rather simple boundary value problems.
Soil strength characterisation using free-falling penetrometers
Publisher: Thomas Telford Ltd.
Date: 10-2013
Abstract: Free-falling penetrometers (FFPs) are rapid and cost-effective tools that can be used in seabed strength characterisation. To date, FFPs have not been widely used, because of the lack of reliable interpretation methods and well-controlled experimental studies. This paper presents an interpretation method for a thin-shafted FFP based on the results of extensive laboratory model FFP tests and triaxial compression tests on normally consolidated kaolin. In the model tests, a thin-shafted FFP with circular plate tip has been dropped into claybeds with a range of undrained shear strengths at various impact velocities. The FFP has also been pushed into the claybeds at slow constant-penetration rate to provide a comparison between the static and dynamic penetration resistances. Triaxial compression tests have been conducted to provide the critical state parameters, and to study the rate-dependence behaviour of the kaolin. Using these test results, an empirical model is proposed to estimate the undrained shear strength from a thin-shafted FFP test in clay. The applicability of the proposed model is compared with existing methods and numerical solutions.
An extended interpretation of the free-fall piezocone test in clay
Publisher: Thomas Telford Ltd.
Date: 20-03-2017
Discussion: Measuring the plastic limit of fine soils: an experimental study
Publisher: Thomas Telford Ltd.
Date: 02-2016
Measuring the plastic limit of fine soils: an experimental study
Publisher: Thomas Telford Ltd.
Date: 02-2015
Abstract: The Casagrande thread-rolling method for determining the plastic limit of fine-grained soil is heavily dependent on operator judgement and can often give inconsistent or unreliable results. This paper presents an energy-based approach used in the development of an improved testing procedure for the plastic strength limit. A 0·727 kg cone is allowed to fall freely through 200 mm before contacting the surface of the test specimen, with the plastic strength limit determined for a cone penetration depth of 20 mm. For ten mineral clays of intermediate to very high plasticity tested, the plastic limits deduced using the cone were in good agreement with the measured Casagrande plastic limits. The values deduced using an 8 kg contacting cone were consistently lower than the Casagrande limits.
A Cyclic Macro-Element Framework for Consolidation-Dependent Three-Dimensional Capacity of Plate Anchors
Publisher: MDPI AG
Date: 13-02-2021
DOI: 10.3390/JMSE9020199
Abstract: This paper presents a new macro-element modelling framework for plate anchors which enables the effect of pore water pressure changes and the related evolution of soil strength during the process of cyclic loading and consolidation to be captured. The proposed modelling framework combines an advanced macro-element model for plate anchors, expanded to capture the cyclic loading behaviour, with a simple one-dimensional model of undrained shearing and consolidation for a soil element representative of the whole soil mass around the anchor. The representative soil element tracks the effects of changes in effective stress on the soil strength, which in turn governs the anchor capacity in the macro-element model. The two modelling components are linked through a mobilised capacity compatibility condition. It will be firstly shown that such modelling framework is able to capture the expected changes in an anchor’s capacity related to cyclic pore pressure generation and consolidation under one-dimensional cyclic loading of the anchor. Then, the model will be used to explore the plate anchor’s behaviour and failure mechanisms under loading conditions which mobilise its full three-dimensional cyclic loading capacity. The macro-element model will identify some conflicting mechanisms (i.e., the anchor’s kinematic/rotation and soil weakening/strengthening) governing the three-dimensional capacity of the anchor.
Drained monotonic and cyclic capacity of a dynamically installed plate anchor in sand
Publisher: Elsevier BV
Date: 2018
Inclined loading of horizontal plate anchors in sand
Publisher: Thomas Telford Ltd.
Date: 12-2022
Abstract: The performance of plate anchors in sand, relative to clay, is not well understood, particularly for the more realistic case of an inclined load. This paper investigates the effect of load inclination on horizontal plate anchors in sand through centrifuge tests and numerical finite-element simulations. The centrifuge tests were performed on rectangular plate anchors in loose and dense sand, at shallow embedment depths with four different load inclinations. The experiments showed that the anchor capacity of horizontal plates increased progressively as the load inclination became progressively more horizontal, with anchor capacity under pure horizontal loading being approximately 1·8 times higher than that under pure vertical loading. These experimental observations were also replicated in finite-element simulations using a bounding surface plasticity model. Investigation of the underlying failure mechanisms and stress paths showed that the slip planes become longer and the mobilised lateral stresses increase as the load inclination becomes increasingly horizontal, which leads to higher anchor capacities. Finally, the anchor resistance factors from the numerical analyses were decoupled into vertical and horizontal components and represented as interaction diagrams, providing a basis for performing hand calculations of anchor capacity for a given embedment depth, load inclination and relative density.
Dynamic analysis of a smooth penetrometer free-falling into uniform clay
Publisher: Thomas Telford Ltd.
Date: 10-2012
Abstract: The finite-element analysis of free-falling objects penetrating soil deposits is one of the most sophisticated and challenging problems in geomechanics. A robust numerical method will be described here for dealing with such complex and difficult problems. The approach is based on the arbitrary Lagrangian–Eulerian (ALE) method of analysis, the main features and challenges of which are described briefly in the paper. The ALE method is then employed to perform a parametric study of a perfectly smooth penetrometer free-falling into a uniform layer of clay, which deforms under undrained conditions. The effect of the mechanical properties of the clay soil on the penetration characteristics is presented, and an approximate, closed-form expression is derived for the dynamic penetration factor, N dp . Comparisons are made between the deduced values of N dp and published values of the conventional cone factor, N c , and comparisons are made with experimental data to validate the approach.
Consolidation effects on uplift capacity of shallow horizontal plate anchors in dilating sand
Publisher: Thomas Telford Ltd.
Date: 11-2022
Abstract: This paper examines the effect of consolidation on a shallowly embedded horizontal plate anchor in medium dense and dense sand using centrifuge tests, where the loading rate was varied over four orders of magnitude. The experimental results show a 4·8 to 5·5 times increase in anchor capacity as the consolidation condition changes from drained to undrained, driven by a steadily increasing negative excess pore pressure with increasing loading rate. At the highest loading rate, under undrained conditions, the measured maximum negative excess pore pressures reach a steady limit, suggesting the occurrence of cavitation. This increase in anchor capacity with dimensionless velocity is captured using a ‘backbone curve’ interpretation framework that describes the change in capacity between the limiting values of drained and undrained anchor capacity. Calculation of drained anchor capacity is straightforward relative to the more challenging problem of calculating undrained capacity, particularly during cavitation. This was addressed separately through a numerical parametric study (pure undrained analysis) using a bounding surface soil model involving different water depths (cavitation potential), densities and embedment ratios. The numerical results are then synthesised into a simple extended analytical solution to allow estimation of undrained anchor capacity under different densities and water depths.
Soil strength estimation and pore pressure dissipation for free-fall piezocone in soft clay
Publisher: Thomas Telford Ltd.
Date: 10-2014
Abstract: This paper considers centrifuge modelling of free-fall piezocones in soft clay, and interprets the test data to estimate the undrained shear strength and coefficient of consolidation. Data from the free-fall piezocones, which involved dynamic embedment in a normally consolidated kaolin clay s le from various drop heights, were compared with equivalent data from piezocone tests. The undrained shear strength, as interpreted from the acceleration trace of the free-fall piezocone, was found to be in good agreement with that derived from the piezocone penetration tests. The free-fall piezocone is also found to produce identical pore pressure dissipation behaviour as for a statically penetrated piezocone, despite a significant rise in the pore pressure at the start of the dissipation phase.
Interpretation of centrifuge CPT data in normally consolidated silica and carbonate sands
Publisher: Thomas Telford Ltd.
Date: 10-2023
Abstract: This paper presents the results from a systematic investigation into the effects of stress level, penetrometer diameter, penetration depth and relative density on the end resistance (q c ) measured in centrifuge-scale cone penetration tests (CPTs) in a variety of normally consolidated siliceous and carbonate sands. Simple empirical formulations are developed that provide a good description of all measurements and that are consistent with expressions developed in calibration chambers and at field scale. The formulations address the significant discrepancies seen between centrifuge and field scale q c profiles and enable development of q c -based correlations for centrifuge tests that are applicable at full scale, as well as providing a means to interpret very shallow CPTs in the field.
Penetrometer testing in a calcareous silt to explore changes in soil strength
Publisher: Thomas Telford Ltd.
Date: 12-2020
Abstract: This paper describes a centrifuge study using a range of penetrometer tests (T-bar, piezocone and free-fall piezocone) to explore strength changes in a reconstituted, normally consolidated, natural calcareous silt. Various penetrometer test procedures were applied to measure the penetration resistances including monotonic, cyclic and twitch-type movements as well as pauses for pore pressure dissipation. These mobilised combinations of partial or full remoulding, strain softening, consolidation and viscous rate effects. The penetrometer resistance – representing a proxy for strength – reduced by a factor of 4·1 from drained to undrained conditions (at the lowest fully undrained penetration rate). In undrained conditions, viscous enhancement of the penetration resistance raised the tip and shaft resistance in free-fall piezocone tests by ∼2·8 and ∼3·6 times, respectively. The ‘restart’ resistance immediately after the dissipation tests was ∼2·5 times higher than the resistance prior to dissipation, giving an indication of consolidation-induced strength gain. The ‘twitch’ test (using sequential steps decreasing the velocity) captured drainage and viscous rate effects, and also gave a ‘restart’ resistance that showed even greater consolidation effects than from a dissipation test. Overall, the different penetrometer test types and procedures measured resistances in the same soil s le that varied by a factor exceeding 20 from highest to lowest, resulting from different penetration rates and history, due to strain rate, strain level (or remoulding) and consolidation. An expression for the monotonic penetration resistance combining drainage and viscous rate effects was fitted to the response of all tests, spanning orders of magnitude in strain rate.
A non-associative macroelement model for vertical plate anchors in clay
Publisher: Canadian Science Publishing
Date: 11-2021
Abstract: This work proposes a new plastic-hardening, non-associative macroelement model to predict the behaviour of anchors in clay for floating offshore structures during keying and up to the peak load. Building on available models for anchors, a non-associated plastic potential is introduced to improve prediction of anchor trajectory and loss of embedment at peak conditions for a large range of padeye offsets and different pull-out directions. The proposed model also includes a displacement-hardening rule to simulate the force and displacement mobilisation at the early stages of the keying process. The model is challenged and validated against different sets of numerical and centrifuge data. This extensive validation process revealed that two of the four newly introduced model parameters assume a constant value for the range of simulated cases. This suggests that only two of the newly introduced parameters may need to be calibrated for the use of the proposed macroelement model in practice.
Related Organisations
Related Funding Activities
Smart Site Investigation For Offshore Energy Installations In Sand
Start Date: 2022
End Date: 2024
Funder: Australian Research Council
View Funded ActivityA Geotechnical Centrifuge To Underpin Australia's Energy And Construction
Start Date: 2022
End Date: 2023
Funder: Australian Research Council
View Funded ActivityDevelopment Of A Novel Dynamically Installed Anchor Through Australia-Korea Joint Venture Research
Start Date: 2019
End Date: 2020
Funder: University of Western Australia
View Funded ActivitySolutions For Rapid Penetration Into Sand For Offshore Energy Installations
Start Date: 2019
End Date: 2021
Funder: Australian Research Council
View Funded ActivityCrusty Seabeds: From (Bio-)Genesis To Reliable Offshore Design
Start Date: 2020
End Date: 2022
Funder: Australian Research Council
View Funded ActivityLinkage Infrastructure, Equipment And Facilities - Grant ID: LE220100073
Start Date: 07-2022
End Date: 06-2024
Amount: $932,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP200103468
Start Date: 12-2020
End Date: 12-2024
Amount: $400,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP190100914
Start Date: 2019
End Date: 06-2022
Amount: $335,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP220101652
Start Date: 07-2022
End Date: 06-2025
Amount: $370,000.00
Funder: Australian Research Council
View Funded Activity