James Peter Doherty

University of Western Australia | UWA · School of Civil and Resource Engineering

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...

Lateral soil stiffness has a strong influence on the overall strength and fatigue life of well conductors and piles. This paper reviews data from centrifuge testing of a short model pile embedded in carbonate silt, which was subjected to packets of cyclic lateral displacement. Key conclusions are that (i) cyclic lateral stiffness is significantly a...

This paper presents an efficient, practical and automated strategy for deriving Modified Cam Clay parameters from undrained self-boring pressuremeter (SBPM) data. A mixed approach involving a parametric sweep and numerical optimisation is used, with a focus on parameter groups that dominate the Modified Cam Clay response in undrained cavity expansi...

Continuous monitoring of mechanical parameters determining the state of natural and man-made systems is essential in a wide range of engineering disciplines from mechanical to civil and geotechnical engineering. To be effective, the monitoring response time needs to be commensurate with the characteristic time of variation of the processes being mo...

This paper attempts to categorise geotechnical field site characterisation tools in a hierarchical manner, as appropriate for the progression from initial surveys to detailed geotechnical design of specific infrastructure. In general, the hierarchy reflects more the sophistication, and hence cost, of the field tools, although small-scale tools deve...

The paper examines methods for predicting the settlement of deep footings in reconstituted sand. Results from vertical load tests on deep circular plates within a laboratory pressure chamber are interpreted using data from triaxial tests, cone penetration tests (CPTs), and pressuremeter tests obtained for the same reconstituted sand. A simple nonli...

Subsea developments require the design of large numbers of shallow skirted foundations to support structures such as manifolds, pipeline and umbilical terminations and in-line tees. Safe and economic design relies on the accurate assessment of foundation capacity against thousands of load-combinations. Performing these design calculations is a sign...

Lateral soil stiffness has a strong influence on the overall strength and fatigue life of well conductors and piles. This paper reviews data from centrifuge testing of a short model pile embedded in carbonate silt, which was subjected to packets of cyclic lateral displacement. Key conclusions are that (i) cyclic lateral stiffness is significantly a...

Pile foundation design is conventionally conducted using a process of trial and error, where the dimensions of a pile are estimated and the performance is computed and compared with design criteria. The dimensions are varied and the process is repeated in order to converge to a safe and economical design. In this paper, this time-consuming and labo...

This note describes a web based application called “Datamap” that has been developed to address the major challenge of capturing, classifying, organizing and making available geotechnical research data. Datamap is illustrated using an example project at the Australian National Field Testing Facility (NFTF). The example project illustrates the inter...

This paper describes an international exercise aimed at assessing the geotechnical engineering profession’s ability to predict the response of shallow foundations on soft clay subjected to undrained loading. Predictions of bearing capacity varied by more than an order of magnitude and settlement by more than two orders of magnitude. Average and med...

This paper presents field test data from four instrumented rigid square pad foundations on soft clay that were brought to failure under concentric vertical loading. The test programme comprised two unconsolidated undrained (UU) foundation tests as well as two consolidated undrained (CU) tests. In the latter case the two foundations were preloaded t...

Rapid filling of low-permeability cemented paste backfill (CPB) into underground stopes results in the generation of significant excess pore pressures. These are dissipated through conventional consolidation and shrinkage due to cement hydration. Gibson’s solution for excess pore pressures in an accreting sediment can be used to assess the self-wei...

The paper presents the results and interpretation of triaxial compression tests for a uniformly graded fine to medium siliceous sand. These results are used together with data obtained from boundary value problems to provide an objective assessment of the predictive capabilities of a widely accessible and popular constitutive model, referred to as...

This paper presents and discusses a new web based application for analysing piled foundations subject to lateral loads; a common problem in civil engineering. Details of the algorithm used to form and solve the non-linear system of equations are provided, along with details of the application’s deployment on Amazon Web Services cloud infrastructure...

This paper describes an automated algorithm for determining the length and diameter of monopile foundations subject to lateral loads with the aim of minimising the pile weight, whilst satisfying both ultimate and serviceability limit states. The algorithm works by wrapping an optimisation routine around a finite element p - y model for laterally lo...

A split Hopkinson pressure bar (SHPB) was used to characterize the propagation of high intensity large strain compressional waves through cemented paste backfill (CPB). The effects of curing age, cement content, and degree of saturation on stress refraction at interfaces, velocity of propagation, and internal damping in CPB were investigated. The r...

The evolution of the soil-water retention curve (SWRC) for cemented paste backfill (CPB) undergoing cement hydration is evaluated in this paper. A pressure plate apparatus and insertion tensiometers in a continuous drying configuration were used to apply and measure suction, respectively, at different CPB curing ages. In addition to this, a novel e...

Rapid filling of low-permeability cemented paste backfill into underground stopes results in the generation of significant excess pore pressures that are modified by the volume shrinkage accompanying the process of cement hydration. Gibson produced results of an analysis of the excess pore pressures in a simultaneously accreting and consolidating s...

A constant-volume direct simple shear apparatus was used to investigate the effects of confining stress, initial static shear stress and void ratio on the liquefaction resistance of fine-grained tailings. The cyclic resistance ratio (also expressed as the overburden stress correction factor) was found to decrease with increasing confining stresses...

p>Accurate prediction of foundation settlement is increasingly important in onshore and offshore geotechnical design. Reducing land space requires construction on non-ideal soils or above buried infrastructure onshore while offshore shallow foundations require optimization of size to facilitate installation while ensuring tolerances on attached rig...

Cemented paste backfill (CPB) has been observed to achieve greater cemented strength when cured in situ compared with equivalent mixes cured and tested in a laboratory environment. This is in part due to the development of effective stress and generation of elevated temperatures by exothermic cement hydration reactions occurring during curing in a...

This paper presents in-stope measurements of total stress and pore-water pressure at strategic locations within three underground stopes at the Raleigh mine site (Western Australia) that were filled with cemented paste backfill (CPB). The three stopes were very similar in shape. Key differences among the stopes were the filling and resting schedule...

The National Soft Soil Field Testing Facility (NFTF) provides a rare opportunity to extensively characterise an Australian soft estuarine clay and to carry out monitored field tests that can be forecast or back-figured using the extensive characterisation data to improve engineering design methods. Several in situ testing campaigns have been perfor...

Mixtures of cement and mine waste are used as backfill in underground mines to provide support, which enables increased mineral extraction. Unlike most cemented material, the properties of mine backfill are relied upon immediately after cement is added and the material deposited underground. It is not only just the properties of the final cemented...

This paper presents the results from a series of centrifuge tests and three-dimensional finite-element (FE) analyses, which examined the benefits of combining a footing with a monopile as a solution for foundations that are subjected to large moment loading, such as those used for towers and wind turbines. The experiments were carried out in silica...

Predicting the settlement of shallow foundations on sand is a routine task for the geotechnical engineering profession. Despite this, there is no well-accepted solution for this very common problem. The aim of the present paper is to address this by presenting a soil model that is simple enough to be applied in routine engineering practice, but sop...

This paper presents details of the design, fabrication and operation of a laboratory-scale pressuremeter recently built at the University of Western Australia. The device is significantly different to any previously built miniature pressuremeter in that it uses air as the pressurising fluid and the membrane displacement is measured using straingaug...

The widely used modified Cam clay soil model requires five soil parameters. In simulations of standard triaxial tests these parameters appear in certain combinations. An efficient and practical strategy for deriving these parameters is presented in which visual and numerical optimization techniques are used to estimate the values of these combinati...

This paper explores the use of numerical optimisation techniques to calibrate constitutive models based on the stress-strain response measured from in-situ pressuremeter tests. The approach is illustrated using a "virtual" example, where site investigation data are generated artifi cially using fi nite element models with assumed parameters. It is...

The paper presents the results from a series of centrifuge tests which examine the benefits of employing a footing together with a 'standard' monopile as a foundation solution for an offshore wind turbine. The experiments were carried out in firm to stiff kaolin clay and involved monotonic application of lateral loads at an equivalent prototype hei...

Evaluating parameters for complex constitutive models can be a laborious and time consuming task, particularly where data from a number of different tests and test types are available. This paper explores the use of mathematical optimisation techniques to derive parameters for a given constitutive model based on the stress-strain/load-displacement...

This paper addresses the problem of a circular footing of finite but nonzero stiffness embedded in an isotropic nonhomogeneous elastic half-space. The problem is solved by coupling the scaled boundary finite-element method with axisymmetric shell finite elements. The coupling of the two methods is validated by comparing computed solutions with anal...

Solutions are presented for stiffness coefficients to represent the elastic behavior of a caisson foundation embedded in soil. The solutions use a novel numerical technique, the scaled boundary finite element method, combined with shell elements to represent the foundation itself The stiffness coefficients take into account the possibility of nonho...

A technique is developed for analysing elasto-plastic unbounded media by adaptively coupling the finite-element method with the scaled boundary finite-element method. The analysis begins with a finite-element mesh that tightly encloses the load–medium interface, capturing non-linearity in the very near field. The remainder of the problem is modelle...

In this paper the effect of caisson skirt flexibility on the overall load-displacement response of a caisson foundation subjected to vertical, horizontal and moment loads is investigated. The study is carried out numerically using the scaled boundary finite-element method, to represent an elastic half-space, combined with shell finite-elements, to...

A challenging computational problem arises when a discrete structure (e.g. foundation) interacts with an unbounded medium (e.g. deep soil deposit), particularly if general loading conditions and non-linear material behaviour is assumed. In this paper, a novel method for dealing with such a problem is formulated by combining conventional three-dimen...

A novel semi-analytical approach to continuum mechanics, known as the scaled boundary finite-element method, is introduced for elasto-static problems involving an unbounded axisymmetric domain subject to general loading. The efficiency and accuracy of the method is demonstrated through a study showing the convergence of the computed solutions to we...

In this chapter, a novel semianalytical approach to continuum mechanics, known as the “scaled-boundary finite-element” method, is introduced for elasto-static problems involving an unbounded axisymmetric domain subjected to general loading. The accuracy and efficiency of the scaled boundary finite-element solutions are examined in the chapter by co...

The scaled boundary finite-element method is derived for elastostatic problems involving an axisymmetric domain subjected to a general load, using a Fourier series to model the variation of displacement in the circumferential direction of the cylindrical co-ordinate system. The method is particularly well suited to modelling unbounded problems, and...

As a result of stresses experienced during and after the deposition phase, a soil strata of uniform material generally exhibits an increase in elastic stiffness with depth. The immediate settlement of foundations on deep soil deposits and the resultant stress state within the soil mass may be most accurately calculated if this increase in stiffness...

This study uses a semi-analytical technique (the scaled boundary finite-element method) to evaluate the load-displacement response of rigid circular footings embedded in a non-homogeneous elastic half-space. Results are presented in terms of dimensionless elastic stiffness coefficients. The footings are subjected to vertical, horizontal, moment and...

A method for modeling three-dimensional (3D) soil-structure interaction problems in which the unbounded soil domain was treated accurately and efficiently was described. The method combines conventional 3D finite elements in a bounded region near the load-medium interface. It also allows general loading and non-linear material behavior to be modele...

The scaled boundary finite-element method uses a semi-analytical technique to solve the non-homogenous partial differential equations governing the elastostatics of two and three-dimensional continua. When compared to the traditional finite element method, the scaled boundary finite-element method has been shown to provide improved accuracy as well...