Charles Augarde

Durham University | DU · Department of Engineering

The Carbon Trust (2015) “Cable Burial Risk Assessment (CBRA) Methodology” document is widely used in the offshore subsea cable industry to define the cable burial Depth of Lowering (DoL). To-date published work on anchor penetration depths has focused on single homogeneous soil units, offering limited information on the response of different soil l...

The Material Point Method (MPM) is well suited to modelling dynamic solid mechanics problems undergoing large deformations with non-linear, history dependent material behaviour. However, the vast majority of existing material point method implementations do not inherit conservation properties (momenta and energy) from their continuum formulations....

This paper proposes an effective computational tool for brittle crack propagation problems based on a combination of a higher-order phase-field model and a non-conforming mesh using a NURBS-based isogeometric approach. This combination, as demonstrated in this paper, is of great benefit in reducing the computational cost of using a local refinement...

Summary & Overview Offshore Cable Burial: How Deep is Deep Enough? OffShore Wind (OSW) power cable failures currently account for 75% of the cost of all insurance claims associated with OSW projects and faults typically take 100+ days to rectify. In shallow waters cables must be protected from anchors/fishing gear and the primary protection meth...

Raw (unfired) earth represents a sustainable and efficient alternative to traditional construction materials but its dissemination into building practice has been hindered by a relatively high vulnerability to water erosion. Enzyme induced carbonate precipitation (EICP) can improve the durability of earth materials without using traditional chemica...

Dowel-type connections are common in timber engineering, but current design codes are largely based on empiricism and are oversimplified. This inhibits the optimised use of connections, which is essential for the design of economically efficient timber structures. This study investigates the use of 3D computational modelling to predict the slip mod...

Sustainability in the materials we use for construction is a prime concern, focusing on reducing the embodied energy and carbon footprints of the materials used. The cement used in concrete products is responsible for a significant proportion of Man's CO2 emissions and its production requires substantial energy input, as do fired clay products. For...

The development of wind farms across Africa is an attractive solution to meet the increasing electricity demand of a growing and widely dispersed population, whilst ensuring that such electricity provision meets global standards in carbon emissions. However, since vast portions of the continent are underlain by expansive soils, foundation design fo...

Tracing load-displacement paths in structural mechanics problems is complicated in the presence of critical points of instability where conventional load- or displacement control fails. To deal with this, arc-length methods have been developed since the 1970s, where control is taken over increments of load at these critical points, to allow full tr...

Biopolymers are promising potential soil stabilizers due to their ease of application and stabilization efficacy. Biopolymers are biologically occurring polymers that form hydrogels when added to soil in the presence of water. Hydrogels are three-dimensional polymer networks formed through the interaction of polymer chains with soil particles and p...

Many problems in geotechnical engineering involve large movements or rotations, examples include natural processes such as landslides, and man-made processes such as earthmoving and pile penetration. While the use of numerical modelling, primarily the finite element method (FEM), is now routine in geotechnical design and analysis, the limitations o...

Desiccation cracking in clay soils is a combined mechanical and hydraulic problem and such soils can be improved by various methods including reinforcement with fibres. The relationships between tensile strength, cracking resistance and water-retention properties of fibre-reinforced fine-grained soils lack coverage in the literature to date. In thi...

This paper presents an investigation of the mechanical properties of three different earth building materials manufactured by compacting two soils with distinct particle size distributions under two markedly different efforts. Multiple samples of each material have been equalised either inside a climatic chamber at different humidity levels or oven...

Point collocation methods are strong form approaches that can be applied to continuum mechanics problems and possess attractive features over weak form-based methods due to the absence of a mesh. While various adaptive strategies have been proposed to improve the accuracy of weak form-based methods, such techniques have received little attention fo...

Earthen construction materials are the subject of renewed interest due to the rising alarm about environmental pollution from the construction industry. Current research efforts are focused on improving the mechanical properties of earthen materials to make them modern and competitive. To increase strength and improve ductility fibres can be added...

The Material Point Method is a relative newcomer to the world of solid mechanics modelling. Its key advantage is the ability to model problems having large deformations while being relatively close to standard finite element methods, however its use for realistic engineering applications will happen only if the material point can be shown to be bot...

The material point method is ideally suited to modelling large deformation problems in three dimensions, especially in cases where the finite element method struggles due to mesh distortion. However, when the method is used to analyse problems with near-incompressible material behaviour, such as in geotechnical engineering using models with isochor...

Cable ploughing is an important technique for burying and protecting offshore cables. The ability to predict the required tow force and plough performance is essential to allow vessel selection and project programming. Existing tow force models require calibration against full-scale field testing to determine empirical parameters, which may hinder...

This paper is devoted to the development of a stabilised implicit non-ordinary state-based peridynamics approach. We propose a geometrically nonlinear implicit approach focusing on quasi-static analyses. Since the construction of the Jacobian matrix is the most time-consuming step in conducting this nonlinear analysis, we formulate an analytical ex...

Existing guidance on the installation of screw piles suggest that they should be installed in a pitch-matched manner to avoid disturbance to the soil which may have a detrimental effect on the in-service performance of the pile. Recent insights from centrifuge modelling have shown that installing screw piles in this way requires large vertical comp...

The geotechnical construction industry is a major component of the overall construction sector and is strategically important in infrastructure development (transportation, flood and landslide protection, building foundations, waste disposal). Although industry and research in the overall construction sector have been investing significantly in rec...

The geotechnical construction industry is a major component of the overall construction sector and is strategically important in infrastructure development (transportation, flood and landslide protection, building foundations, waste disposal). Although industry and research in the overall construction sector have been investing significantly in rec...

Screw piles potentially offer quieter installation and enhanced axial tensile capacity over straight-shafted driven piles. As such, they have been suggested as a possible foundation solution for offshore jacket supported wind turbines in deeper water. To investigate the feasibility of their use in this setting, centrifuge testing of six model screw...

Screw anchors have been recognised as an innovative solution to support offshore jacket structures and floating systems, due to their low noise installation and potential enhanced uplift capacity. Results published in the literature have shown that for both fixed and floating applications, the tension capacity is critical for design but may be poor...

Earthen construction materials are often chemically stabilised in order to improve their durability against water-induced deterioration. However, chemical stabilisers like cement can negatively affect the hygroscopic behaviour and recyclability potential of the materials they are used to stabilise. This study investigates the potential of using bio...

This paper proposes an effective computational tool for brittle crack propagation problems based on a combination of a higher-order phase-field model and a non-conforming mesh using a NURBS-based isogeometric approach. This combination, as demonstrated in this paper, is of great benefit in reducing the computational cost of using a local refinement...

The Material Point Method (MPM) is a computational tool ideally suited to modelling solid mechanics problems involving large deformations where conventional mesh-based methods struggle. Explicit and implicit formulations are available, but for both the learning curve for understanding the method and arriving at a useful implementation is severe. Re...

Civil engineering research is increasingly focusing on the development of sustainable and energy-efficient building materials. Among these materials, raw (unfired) earth constitutes a promising option for reducing the environmental impact of buildings over their entire service life from construction to demolition. Raw earth has been used since old...

The Material Point Method is a computational tool ideally suited to modelling solid mechanics problems involving large deformations where conventional mesh-based methods struggle. Explicit and implicit formulations are available, but for both the learning curve for understanding the method and arriving at a useful implementation is severe. Research...

Cable ploughing is one of the most common means by which subsea cables are buried. Prediction of the cable plough behaviour is important and has the potential to reduce installation costs for offshore renewables. Prediction of tow force and final burial depth is a key factor in choosing appropriate installation equipment and estimating progress rat...

The material point method is ideally suited to modelling problems involving large deformations where conventional mesh-based methods would struggle. However, total and updated Lagrangian approaches are unsuitable and non-ideal, respectively, in terms of formulating equilibrium for the method. This is due to the basis functions, and particularly the...

Implicit boundary methods, which enrich the interpolation structure with implicit weight functions, are straightforward methods for the enforcement of Dirichlet boundary conditions. In this article, we follow the implicit boundary method that uses approximate step functions (the step boundary method) developed by Kumar et al. and provide modificati...

Earthen structures (i.e. structural units manufactured from soil) are often regarded as sustainable forms of construction due to their characteristically low carbon footprint. Unstabilised earthen materials can easily be recycled or disposed, however, modern earthen structures rely on cement to obtain desirable strength and durability. This lowers...

The demands of innovative, cost effective and sustainable construction practices requires the development of energy-efficient and environmental friendly building techniques. The achievement of this objective is helped by the exploitation of knowledge from different disciplines, including physics, biology and chemistry. In geotechnical engineering,...

Challenging solid mechanics problems exist in areas such as geotechnical and biomedical engineering which require numerical methods that can cope with very large deformations, both stretches and torsion. One candidate for these problems is the Material Point Method (MPM), and to deal with stability issues the standard form of the MPM has been devel...

Stabilization is often necessary to improve the stiffness, strength and durability of both natural and compacted soils. Soils are typically stabilized via the addition of hydraulic binders, such as cement and lime, which present however relatively high carbon and energy footprints. Alternative stabilization techniques are therefore explored to mini...

Stabilization is often necessary to improve the stiffness, strength and durability of both natural and compacted soils. Soils are typically stabilized via the addition of hydraulic binders, such as cement and lime, which present however relatively high carbon and energy footprints. Alternative stabilization techniques are therefore explored to mini...

This paper presents a novel combination of two numerical techniques to produce a method for solving fracture mechanics problems. A weak form meshless method, the cracking particles method, forms the basis of the mechanical model while crack propagation direction is calculated using configurational forces. The combined method is presented here for 2...

Highlights • An adaptive cracking particle method has been developed for thermoelastic fracture problems. • Crack discontinuities are handled by the visibility criterion rather than enrichment functions, which can avoid extra unknowns and ill-conditioned system stiffness matrix. • Thermal gradients around crack tips are captured by dense groups of...

Creating accurate models of the Earth’s surface is an essential step when analysing geomorphological changes through time. Alongside photogrammetry, airborne lidar is an established method for measuring and modelling the Earth’s surface. However, improvements in size, weight and power requirements mean that lidar is now increasingly capable of bein...

In this paper, the development is described of a strong form-based local maximum entropy point collocation approach to analyse simple membrane problems. Point collocation methods work with discretised strong forms, presenting some attractive features, e.g. no background mesh. In this analysis, three configurations including the reference, prestress...

This volume forms the proceedings of the 1st International Symposium on Screw Piles for Energy Applications (ISSPEA), held at the University of Dundee, 27-28th May, 2019. This conference is the first such event organised at the University of Dundee and was originally designed to be a small event to disseminate the findings of the EPSRC sponsored Su...

This paper focuses on applying implicit time stepping approaches to a non-ordinary state-based peridynamics formulation for quasi-static problems. The paper is restricted to two-dimensional large deformation analysis with linear elastic material behaviour with a modified correspondence model to suppress spurious zero energy modes. Equilibrium is ob...

In this article we first review various approaches developed to date for the weak imposition of Dirichlet boundary conditions in fictitious domain analysis for elasticity problems. The Hellinger–Reissner (H–R) principle, the linked Lagrange multiplier (LLM) method, the implicit boundary method and the fat boundary method are discussed along with th...

In the majority of cases, earthen construction materials for real buildings require amendment to deliver suitable material properties, which could be some additional strength or resilience to erosion. In modern earthen construction, in India, Australia and other parts of the world, cement and lime have been successfully used as stabilisers, providi...

The material point method is an increasingly popular method for tackling solid mechanics problems involving large deformations. However, there are issues associated with applying boundary conditions in the method and, to date, no general approach for imposing both Neumann and Dirichlet boundary conditions has been proposed. In this paper, a new B-s...

Offshore pipeline ploughs have previously been modelled at 1g with small 1/50th scale models designed to derive the parameters required for prediction of ploughing in terms of tow force requirements and potential advance rates. This was scaled up to prototype with the validity of the scaling verified through modelling of models and with comparison...

Numerical time integration plays an important role in engineering analysis codes. The original formulation of the peridynamics computational methods were solved using explicit time integration and the majority of previous non-ordinary state-based peridynamics implementation have adopted explicit formulations. Typically explicit time integration is...

The effect of pore suction and water content on the engineering properties of partially saturated soils has been extensively studied by geotechnical researchers. It is well known that unsaturated soils become stiffer, stronger and less permeable as suction increases and saturation decreases. The results from these studies are however not directly a...

The effect of pore suction and water content on the engineering properties of partially saturated soils has been extensively studied by geotechnical researchers. It is well known that unsaturated soils become stiffer, stronger and less permeable as suction increases and saturation decreases. The results from these studies are however not directly a...

Biopolymers are known to achieve significant soil stabilisation when working with small quan-tities. There have been studies understanding their effects on permeability, strength, compressibility and dura-bility, however, there are few studies exploring their potential as stabilisers in earthen construction. An earth-en material is typically stabil...

Introduction  Earthen construction refers to use of subsoil materials to form structural members such as walls  Techniques are both unit based (earth blocks) or in situ (rammed earth)  Modern earthen materials rely on energy consuming stabilisers like cement for strength and durability  Biopolymers can be viable alternatives to cement in prov...

Screw piles (helical piles) can provide a viable, cost-effective and low-noise installation alternative to increasing the size of existing foundation solutions (e.g. monopiles) to meet the demand for the advancement of offshore wind energy into deeper water. Significant upscaling of widely used onshore screw pile geometries will be required to meet...

This paper presents a study, at material scale, of the dependency between particle size distribution and the mechanical, hygroscopic and durability properties of compacted raw (unfired) earth for manufacturing bricks. Stiffness and strength are measured by unconfined compression tests while vapour adsorption/desorption is investigated by moisture b...

The Material Point Method (MPM) is a quasi Eulerian-Lagrangian approach to solve solid mechanics problems involving large deformations. In order to improve the stability of the MPM, several extensions have been proposed in the last decade. In these extensions, the sudden change of stiffness when a point crossing an element boundary in the standard...

The Material Point Method (MPM) for solid mechanics was first proposed by Sulsky and co-workers in the 1990s. Since then it has been developing a growing band of followers not least because of its ability to handle large deformation problems with ease. This feature has more recently come to the notice of geotechnical researchers who have plenty of...

Screw piles have been suggested as an alternative foundation solution to straight-shafted piles for jacket supported offshore wind turbines in deep water. The significant environmental loads in the marine environment will require substantially larger screw piles than those currently employed in onshore applications. This raises questions over the s...

Most numerical methods in solid mechanics work with discretised weak-forms. Point collocation methods work with discretised strong-forms and have received much less study. Adaptivity procedures have been used for many years to improve the efficiency of weak-form based methods. For instance r-adaptivity in [1] is for finite element methods where the...

Cracks in 3D have arbitrary shapes and therefore present difficulties for numerical modelling. A novel adaptive cracking particle method with explicit and accurate description of 3D cracks is described in this paper. In this meshless method, crack surfaces are described by a set of discontinuous segments which are associated with particles. This gr...

Practical fracture problems are characterised by complex patterns of multiple and branching cracks, somewhat far removed from the fracture problems used for validation of numerical methods, involving single cracks, and the simulation of complex multi-tipped cracks brings many challenges to current numerical methods. The cracking particle method (CP...