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Modelo teórico para controle da capacidade de carga à tração de estacas metálicas helicoidais em solo arenoso; Theoretical model to control on site the uplift capacity of helical screw piles embedded in sandy soil

Tsuha, Cristina de Hollanda Cavalcanti
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 26/11/2007 PT
Relevância na Pesquisa
36.72%
O monitoramento em campo de fundações em estacas metálicas helicoidais é baseado em correlações empíricas entre a capacidade de carga à tração e o torque medido durante a instalação. Nesta pesquisa é proposto um modelo teórico da relação entre o torque de instalação e a capacidade de carga à tração deste tipo de estaca em areias para ser utilizado como procedimento de controle durante a execução deste tipo de fundação. Para validar esta relação teórica e para avaliar o desempenho desta fundação em solos arenosos, foi realizado um programa experimental dividido em dois grupos: ensaios de campo e ensaios de laboratório. Em campo foram realizadas provas de carga à tração na Escola de Engenharia de São Carlos (EESC) e em Contagem (Minas Gerais). Os ensaios de laboratório foram divididos em três grupos. O primeiro corresponde aos ensaios de modelagem física em centrífuga realizados no Laboratoire Central des Ponts et Chaussées (LCPC) em Nantes, França. O segundo engloba ensaios de cisalhamento direto de interface entre o aço da hélice da estaca e diferentes areias, parte executada no LCPC e parte na EESC. O terceiro grupo refere-se a ensaios de torção de tubos de estacas metálicas helicoidais efetuados na EESC. A partir dos resultados dos ensaios...

Physical modelling of Flowslide Mobility

Davoodi Bilesavar, ROYA
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 4752993 bytes; application/pdf
EN; EN
Relevância na Pesquisa
36.63%
Static liquefaction is a sudden decrease of soil shear strength due to the rapid development of pore pressures generated during the collapse of loose, saturated soil deposits. If this type of failure occurs in sloping soils, a flowslide can result. Viscous debris moving down a slope with high velocity could cover a vast area and cause significant loss of life and property. The primary objective of this study was to investigate the triggering factors of liquefaction in shallow slopes through the physical modeling technique of centrifuge testing. A flowslide simulator was developed to investigate the factors that lead to the liquefaction of soil slopes. This simulator was capable of replicating groundwater regimes and intense rainfalls with pore pressure transducers to monitor the pore pressure changes in the model slope and digital cameras to calculate the resultant slope deformation, velocity, and acceleration using the Particle Image Velocimetry method (PIV) of digital image correlation. In the course of this research, four centrifuge tests have been performed to evaluate the triggering mechanisms of fast landslides in shallow slopes. A seepage induced failure was simulated in the first test. The second and third tests were conducted applying different groundwater regimes in combination with intense rainfall to bring the slope to failure. The last test was a rainfall induced failure in the absence of a pre-existing groundwater table. The results from these experiments illustrate that the initial groundwater level has a considerable effect on the mobility of flowslides.; Thesis (Master...

Role of reactivated basement faults in localizing deformation in the upper crust: Insights from centrifuge analogue modelling

Waffle, Lindsay
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
36.63%
Dynamically scaled centrifuge analogue models are used to investigate recent interpretation of enhanced gravity data, which highlights northeast-striking inherited faults in the crust of northern India. The reactivation of these faults in the subducting Indian crust during the collision of India and Asia in the Paleogene (ca. 45–40 Ma) and early Neogene (ca. 20–15 Ma) is investigated to elucidate their potential role in localizing deformation in the upper crust. Models consist from bottom to top of a rigid basement material, a ductile middle, a layered package representing the upper crust, and a near-surface brittle layer. Viscoelastic materials used as analogues for the mid- and lower crust demonstrate complex dynamic behaviour; effective viscosity alone is not sufficient to determine if a material will be an effective analogue. Two series of rheological experiments are conducted using an oscillating parallel-plate rheometer to measure the storage and loss moduli and effective viscosities of potential materials. Inherently cohesive synthetic sands are suggested as suitable analogues for the brittle upper crust, historically not reproduced in centrifuge models. In models simulating early stage collision (ca. 10 Myr after onset)...

CENTRIFUGE MODELLING STUDY OF CONTRASTING STRUCTURAL STYLES IN THE SALT RANGE AND THE POTWAR PLATEAU, PAKISTAN

FAISAL, SHAH
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
66.88%
The ENE-trending Himalayan fold-thrust belt in Pakistan exhibits contrasting deformation styles both along and across the strike. The centrifuge modelling technique has been used to investigate these variations in structural style. For the purpose of modelling, the Salt Range and Potwar Plateau (SR/PP) stratigraphy has been grouped into four mechanical units. From bottom to top these are the Salt Range Formation, carapace unit (Cambrian-Eocene platform sequences), Rawalpindi Group, and Siwalik Group. These stratigraphic units of alternating competence, composed of thin layers of plasticine modelling clay and silicone putty, rest on a rigid base plate that represents the crystalline basement of the Indian plate. The models are built at a linear scale ratio of ~10-6 (1mm=1km) and deformed in a centrifuge at 4000g. The models are subjected to horizontal shortening by collapse and lateral spreading of a “hinterland wedge” which simulates overriding by the Himalayan orogen (above the Main Boundary Thrust). The models of the central SR/PP show that the accretionary wedge develops a prominent culmination structure with fault-bend fold geometry over the frontal ramp, while the eastern SR/PP is more internally deformed by detachment folds...

Physical modelling of landslides in loose granular soils

Beddoe, Ryley
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
36.77%
The catastrophic consequences associated with landslides necessitate predictions of these hazards to be made with as much certainty as possible. However, the often complex nature of these events make predictions highly challenging. In this thesis, a number of hypotheses related to the triggering mechanisms and subsequent consequences of landslides in a loose-granular soil were investigated. The investigation was conducted using small-scale geotechnical centrifuge models, and a new flume facility developed to examine landslide behavior in a reduced-scale model. The first hypothesis explored in this research was that static liquefaction might preferentially occur in the saturated granular soil located at the base of the landslide rather than the well-drained inclined portion of the slope. Using a geotechnical centrifuge model, it was found that a small initial toe failure did act as a monotonic loading trigger to shear the loose contractile saturated sand at the base of the slope and caused liquefaction to occur. The second hypothesis investigated whether the consequences of a landslide triggered under elevated groundwater antecedent conditions are higher than scenarios under drier antecedent conditions. Results from five centrifuge models subjected to different antecedent groundwater conditions show that higher groundwater conditions can result in landslides with velocities about three times higher and travel distances eight times higher than low antecedent conditions. The third hypothesis investigated the influence of slope inclination on landslide consequences. Seven geotechnical centrifuge models were built and tested...

Investigation of Softening Instability Phenomena Under Simulated Infinite Slope Conditions in Centrifuge Tilting Table Tests

Wolinsky, Eric
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
36.62%
Element test results reported in the literature under both triaxial and plane strain conditions indicate that loose saturated granular specimens can experience softening instability at stress ratios lower than what might otherwise be expected given the critical state friction angle of the soil. The region of potential softening instability in stress-space is often explained using the framework of the instability line. This phenomenon is particularly relevant to shallow slopes of 1 to 2 m depth. However, the practical realities of sample preparation for triaxial testing make performing tests below 20 to 30 kPa of confining stress exceptionally difficult. In this thesis, the development of a centrifuge tilt-table test device is described which aims to test the behaviour of loose granular slopes under stress paths of increasing slope inclination or increasing pore water pressure. A system of instrumentation including pore pressure transducers, inclinometers, displacement transducers, and high-resolution cameras was designed to monitor the behaviour of the slope model. The development of a system to provide a controlled groundwater level within the slope model proved to be particularly challenging. The results of two competing design concepts are presented for the water boundary condition and discussed. The centrifuge tilt-table is used to compare the physical response of a slope to the behaviour predicted by the infinite slope and softening instability models using scale model centrifuge testing. If softening instability is a rigorous concept...

Ground movements during tunnelling in sand

Thorpe, Jason Peter
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 2791272 bytes; application/pdf
EN; EN
Relevância na Pesquisa
36.35%
During soft ground tunnel construction, if the face pressure of a tunnel boring machine is not strictly controlled, excessive ground movements will propagate vertically upwards causing significant damage to adjacent buried infrastructure and surface structures. In order to investigate the face pressure - ground deformation relationship for tunnels in sands, the construction process was modelled using the technique of geotechnical centrifuge modelling and the resulting ground deformations were recorded using digital image correlation. In these tests a unique tunnel face boundary condition was developed which allowed the boundary condition to be initially set as a zero strain condition before it was transformed into a load-controlled boundary to investigate the instability of the face. Tests were preformed at four different burial depths in dry sand, corresponding to cover depths of 0.5, 1, 1.5, and 2 times the tunnel diameter. These results indicate that the face pressure at failure is largely independent of burial depth over the values tested. The ground deformation at the onset of tunnel face instability was found to be very small, and once initiated, the zone of ground deformations was observed to propagate upwards in a narrow chimney in front of the tunnel until it reached the ground surface causing subsidence. Further tests investigated the variation in ground deformations to be expected if a tunnel were to be passing through more complex ground conditions...

Physical Modelling of the Mobility of Dry Granular Landslides

Bryant, SARAH
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
36.76%
In geotechnical engineering, granular flows are often studied as a means to further the understanding of the mechanisms that drive landslide motion. High quality experimental data is essential in providing evidence for the development and verification of new theoretical methods that link complex grain interactions to the extended mobility of some landslide events. At present, limited experimental data is available that captures the full range of landslide mobility. In an attempt to add to the present data sources, high quality experimental data was obtained through the use of high speed cameras and physical modelling using a geotechnical centrifuge and a large scale landslide flume. These modelling techniques allow for landslide motion, representative of field scale events, to be observed in a well-defined and controlled setting. A series of nine tests were performed in a geotechnical centrifuge under varying slope inclinations and Coriolis conditions. The effects of Coriolis on landslide mobility were evident when comparing final deposit shapes and total runout. The effects of Coriolis were more pronounced for higher velocity situations and when material was travelling on the horizontal base section opposed to the sloped section of the physical model. A series of thirty tests were performed using a large scale flume under varying source volumes and basal friction conditions...

Centrifuge Modelling of Instability in Granular Soils under Infinite Slope Conditions

Jacobs, EMILY
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
46.63%
Rainfall induced granular flow slides pose a significant risk in many areas of the world. These failures, characterized by the sudden release of material in a fluid-like manner, are the result of static liquefaction occurring in these slopes. The static liquefaction phenomenon has been linked to instability. Instability behaviour is primarily studied under undrained triaxial conditions, and although many instability theories have therefore been defined in this stress space, these have been shown to also extend into plane strain conditions. In order to further investigate this behaviour under these stress conditions, Wolinsky et al. (2013) developed a tilt-table soil box for use in a geotechnical centrifuge to analyze instability in infinite slope soil models. This testing apparatus has been used to simulate instability in plane strain under both dry and saturated soil conditions. Stress-controlled experiments were performed on dry infinite slope soil models to investigate the effects of both void ratio and effective stress on instability behaviour. By performing these tests dry, this test apparatus provides the ability to decouple the triggers of instability from the corresponding response in pore pressure and the consequences. The results of this testing confirmed that the instability line angle is a function of both void ratio and effective stress. As the void ratio decreases and effective stress in the soil model increases...

Numerical modelling of unsaturated-saturated flow under centrifugation with no outflow

Kacur, J.; Malengier, B.; Kison, P.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 07/01/2010
Relevância na Pesquisa
26.35%
A novel centrifuge set-up for the study of unsaturated flow characteristics in porous media is examined. In this set-up, simple boundary conditions can be used, but a free moving boundary between unsaturated-saturated flow arises. A precise and numerically efficient approximation is presented for the mathematical model based on Richards' nonlinear and degenerate equation expressed in terms of effective saturation using the Van Genuchten-Mualem ansatz for the soil parameters in the unsaturated zone. Sensitivity of the measurable quantities (rotational moment, center of gravity and time period to achieve quasi steady state) on the soil parameters is investigated in several numerical experiments. They show that the set-up is suitable for the determination of the soil parameters via the solution of an inverse problem in an iterative way, excluding the saturated hydraulic conductivity. For this parameter, an existing simple centrifuge set-up is repeated and augmented with transient measurements.

Interaction between surface structures and tunnelling in sand: centrifuge and computational modelling

Giardina, Giorgia; DeJong, Matthew J.; Mair, Robert J.
Fonte: Elsevier Publicador: Elsevier
Tipo: Article; published version
EN
Relevância na Pesquisa
36.63%
This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.tust.2015.07.016; The dataset supporting this article can be found on the Cambridge University Repository at https://www.repository.cam.ac.uk/handle/1810/249085.; Tunnelling in urban areas requires a careful estimation of the consequence of soil settlements on existing buildings. In this paper the interaction between the excavation of a tunnel in sand and surface structures is investigated. A two dimensional finite element model is presented and validated through comparison with centrifuge test results, both with and without structures. The model is then used to perform a sensitivity study on the effect of building weight on soil movements and structural deformations. The results of the validation indicate that assuming a no-tension interface between the soil and the structure is essential to capture the soil-structure interaction that was experimentally observed. The parametric analyses show that the relation between the building stiffness and the tunnelling-induced deformations depends on the building weight.; Financial support was provided by the Engineering and Physical Sciences Research Council of the United Kingdom, under grant reference number EP/K018221/1.

Submarine landslide flows simulation through centrifuge modelling

Gue, Chang Shin
Fonte: University of Cambridge; Department of Engineering Publicador: University of Cambridge; Department of Engineering
Tipo: Thesis; doctoral; PhD
EN
Relevância na Pesquisa
57.01%
Landslides occur both onshore and offshore. However, little attention has been given to offshore landslides (submarine landslides). Submarine landslides have significant impacts and consequences on offshore and coastal facilities. The unique characteristics of submarine landslides include large mass movements and long travel distances at very gentle slopes. This thesis is concerned with developing centrifuge scaling laws for submarine landslide flows through the study of modelling submarine landslide flows in a mini-drum centrifuge. A series of tests are conducted at different gravity fields in order to understand the scaling laws involved in the simulation of submarine landslide flows. The model slope is instrumented with miniature sensors for measurements of pore pressures at different locations beneath the landslide flow. A series of digital cameras are used to capture the landslide flow in flight. Numerical studies are also carried out in order to compare the results obtained with the data from the centrifuge tests. The Depth Averaged Material Point Method (DAMPM) is used in the numerical simulations to deal with large deformation (such as the long runout of submarine landslide flows). Parametric studies are performed to investigate the validity of the developed centrifuge scaling laws under the initial and boundary conditions given in the centrifuge tests. Both the results from the centrifuge tests and numerical simulations appear to follow the proposed centrifuge scaling laws...

A new apparatus for modelling excavations

Lam, Sze Yue; Elshafie, Mohammed Z. E. B.; Haigh, Stuart K.; Bolton, Malcolm D.
Fonte: Institution of Civil Engineers Publicador: Institution of Civil Engineers
Tipo: Article; published version
EN
Relevância na Pesquisa
26.48%
This is the final published version. It first appeared at http://www.icevirtuallibrary.com/content/article/10.1680/ijpmg.2012.12.1.24.; Underground space is commonly exploited both to maximise the utility of costly land in urban development and to reduce the vertical load acting on the ground. Deep excavations are carried out to construct various types of underground infrastructure such as deep basements, subways and service tunnels. Although the soil response to excavation is known in principle, designers lack practical calculation methods for predicting both short- and long-term ground movements. As the understanding of how soil behaves around an excavation in both the short and long term is insufficient and usually empirical, the judgements used in design are also empirical and serious accidents are common. To gain a better understanding of the mechanisms involved in soil excavation, a new apparatus for the centrifuge model testing of deep excavations in soft clay has been developed. This apparatus simulates the field construction sequence of a multi-propped retaining wall during centrifuge flight. A comparison is given between the new technique and the previously used method of draining heavy fluid to simulate excavation in a centrifuge model. The new system has the benefit of giving the correct initial ground conditions before excavation and the proper earth pressure distribution on the retaining structures during excavation...

Dataset for "Interaction between surface structures and tunnelling in sand: centrifuge and computational modelling"

Giardina, Giorgia; DeJong, Matthew J.; Mair, Robert J.
Fonte: Universidade de Cambridge Publicador: Universidade de Cambridge
Tipo: Relatório Formato: .fig, Matlab
Relevância na Pesquisa
26.5%
The article associated with this dataset can be found at http://dx.doi.org/10.1016/j.tust.2015.07.016; Raw data supporting figures in the publication: Giardina G, DeJong MJ, Mair RJ (2015) Interaction between surface structures and tunnelling in sand: centrifuge and computational modelling. Tunnelling and Underground Space Technology, 50, 465-478.; This work was supported by the EPSRC [grant number EP/K018221/1].

Centrifuge Modeling of Deep Excavations and Their Interaction With Adjacent Buildings

Elshafie, M. Z. E. B.; Choy, C. K. C.; Mair, R. J.
Fonte: ASTM International Publicador: ASTM International
Tipo: Article; accepted version
EN
Relevância na Pesquisa
46.56%
This is a preprint of an article published in Geotechnical Testing Journal. The final version is available from http://www.astm.org/DIGITAL_LIBRARY/JOURNALS/GEOTECH/PAGES/GTJ20120209.htm.; Major cities in the world are experiencing a rapid growth in population while becoming increasingly overcrowded and congested. In recent years, this has created a huge demand for underground infrastructure, which often involves the design of major mass transit tunnel systems; these tunnel systems (underground tunnels and metro stations) are becoming increasingly necessary to construct in very close proximity to existing buildings. The prediction of excavation-induced deformations therefore becomes a key issue in the planning and design process for these schemes. However, current design approaches are conservative and often lead to unnecessary concern and expenditure in the design and provision of protective measures. A better understanding of the mechanisms involved in the excavation-soil-structure interaction could reduce costs and help avoid potential problems. A series of small-scale model tests was carried out in the geotechnical centrifuge at Cambridge University to investigate the interaction between excavations and model buildings. Excavations (simulated by adopting a novel two-fluid technique) in a ?free-field? were also undertaken to assess the difference between free-field ground movements and those affected by a stiff model building. A detailed description of the centrifuge models and test procedures is presented in this paper...

On preparation of viscous pore fluids for dynamic centrifuge modelling

Adamidis, O.; Madabhushi, S. P. G.
Fonte: ICE Publicador: ICE
Tipo: Article; accepted version
EN
Relevância na Pesquisa
46.63%
This is the accepted manuscript currently embargoed pending publication. Permission is granted by ICE Publishing to print one copy for personal use. Any other use of these PDF files is subject to reprint fees.; The scaling laws that arise from dynamic centrifuge modelling contain an inconsistency between the scaling of time for dynamic events and diffusion events. This problem can be resolved by reducing the permeability of the soil, with the help of high viscosity pore fluids. Hydroxypropyl methylcellulose is a water soluble cellulose ether that is widely used to create such fluids. In this paper, the effects that concentration, temperature, ageing, and shearing rate have on the viscosity of hydroxypropyl methylcellulose solutions are examined and equations that quantify them are presented. This information is meant to act as a guideline in preparing high viscosity pore fluids for dynamic centrifuge tests.

Scale effects in tests on footings

Lau, Chi Keung
Fonte: University of Cambridge; Christ's College Publicador: University of Cambridge; Christ's College
Tipo: Thesis; doctoral; PhD
EN
Relevância na Pesquisa
26.5%
This dissertation presents an investigation of the effects of stress, and of absolute and relative particle size, in tests on vertically loaded footings. Two granular materials, namely, a silica rock flour and a Chatelet flint grit, which differed in nominal diameter by a factor of 50 but were otherwise practically similar in all other grain characteristics were used in this work. A comprehensive series of triaxial tests under a wide range of cell pressures was carried out to quantify the stress and absolute particle size effects. Model footing tests were also performed by pushing a rigid circular punch axisymmetrically into the flat surface of a cylindrical soil model either under 1-g (gravity) with surcharge or under elevated g in a centrifuge. The 1-g and centrifuge test series were used to study the scale effects on the surcharge term Ng and the self-weight term N? of the Terzaghi bearing capacity equation, respectively. Parameters varied were punch diameter, particle size and surcharge or g level. Two theoretical analyses were attempted based on the finite element method and the method of characteristics. Using the Schofield Soil Model, the finite element analysis can give a reasonable order of magnitude prediction for the settlement of the footing under working load conditions. When the effect of reducing angle of shearing with increasing stress was taken into account together with the change of geometry due to footing penetration...

Dynamic response of flexible square tunnels: testing and validation of existing design methodologies

Tsinidis, G.; Pitilakis, K.; Madabhushi, G.; Heron, C.
Fonte: ICE Publishing Publicador: ICE Publishing
Tipo: Article; published version
EN
Relevância na Pesquisa
36.8%
This is the final published version. It first appeared at http://www.icevirtuallibrary.com/content/article/10.1680/geot.SIP.15.P.004; A series of dynamic centrifuge tests were performed on a flexible aluminium square tunnel model embedded in Hostun dry sand. The tests were carried out at the centrifuge facility of the University of Cambridge in order to further improve knowledge regarding the seismic response of rectangular embedded structures and to calibrate currently available design methods. The soil?tunnel system response was recorded with an extensive instrumentation array, comprising miniature accelerometers, pressure cells and position sensors in addition to strain gauges, which recorded the tunnel lining internal forces. Tests were numerically analysed by means of full dynamic time history analysis of the coupled soil?tunnel system. Numerical predictions were compared to the experimental data to validate the effectiveness of the numerical modelling. The interpretation of both experimental and numerical results revealed, among other findings: (a) a rocking response of the model tunnel in addition to racking; (b) residual earth pressures on the tunnel side walls; and (c) residual internal forces after shaking, which are amplified with the tunnel's flexibility. Finally...

Dynamic centrifuge testing of cantilever retaining walls

Ortiz, L. Alexander
Fonte: California Institute of Technology Publicador: California Institute of Technology
Tipo: Report or Paper; PeerReviewed Formato: application/pdf
Publicado em 01/01/1982
Relevância na Pesquisa
36.48%
An investigation was made into the behavior of flexible cantilever walls retaining a cohesionless soil backfill and subjected to earthquake-type dynamic excitations using the centrifuge modelling technique. The study was motivated by the abundant observations of earth retaining structure damage and failures documented in earthquake damage reports. The "prototype" typical walls were designed using the traditional Mononobe-Okabe dynamic lateral earth pressure theory, were properly scaled for use in the centrifuge at 50 g's, and were subjected to lateral earthquake-like motions which were considered to be of realistic levels. The walls were amply instrumented with pressure and displacement transducers, accelerometers, and strain gages. Moment, pressure, shear, and displacement distributions (static, dynamic, and residual) were obtained. From the test data, some empirical curves for relating the upper bound responses of the retaining walls to the strong motion characteristics of the applied earthquakes were obtained.

Centrifuge modelling of a soil nail retaining wall

Jacobsz,S W
Fonte: Journal of the South African Institution of Civil Engineering Publicador: Journal of the South African Institution of Civil Engineering
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2013 EN
Relevância na Pesquisa
56.84%
This paper describes a physical model of a soil nail retained excavation face which was tested in the new geotechnical centrifuge at the University of Pretoria. As centrifuge modelling is new in South Africa, a short introduction to this technique is presented. The mobilisation of soil nail forces and their maximum values in response to excavation in the model were compared to measurements recently made in an instrumented 10 m high soil nail retaining structure for the Gautrain system in Pretoria. Results were also compared to predictions made using a simple failure wedge analysis and a database of eleven full-scale instrumented soil nail walls from the literature. The centrifuge model data compared well with both full-scale situations and theoretical analyses. The results suggest that soil nail forces measured in the centrifuge are conservative due to the mobilisation of a portion of the shear strength of the model soil during the acceleration of the centrifuge, leaving less un-mobilised shear strength available to resist loads resulting from the excavation.