bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of a new pile driving actuator and a fully instrumented model pile for use in the centrifuge
Authors: Klotz E.U. , Taylor R.N.
Published: November 2015

A new actuator and a fully instrumented model pile have been developed at the Geotechnical Engineering Research Centre at City University to study the behaviour of jacked piles in sands by means of centrifuge testing. The actuator and strong box assembly were designed to operate at up to 200 g. The model pile was instrumented with eleven transducers allowing the base resistance, local shaft resistance and the radial stresses to be monitored continuously during pile installation. The pile has a diameter of 16 mm and is 350 mm long, thus at 200 g represents a prototype pile of 3.2 m diameter and 70 m length. The paper describes the stages of development of both the actuator and the model pile. In addition the process of calibration and the corrections applied to the test data are described in detail. Finally some typical test data are presented and the accuracy of the measurements is discussed.
Development of sensors, probes and imaging techniques for pollutant monitoring in geo-environmental model tests
Authors: Lynch R. J. , Allersma H. , Barker H. , Bezuijen A. , Bolton M. D. , Cartwright M. , Davies M. C. R. , Depountis N. , Esposito G. , Garnier J. , Garrett J. L. L. De Almeida , Harris C. , Kechavarzi C. , Oung O. , Da Silva M. A. G. , Santos C. , Sentenac P. , Soga K. , Spiessl S. , Taylor R. N. , Treadway A. C. J. , Weststrate F.
Published: November 2015

In order to be able to track the movement of pollutant plumes during geotechnical centrifuge and other geo-environmental experiments, a number of techniques have been investigated: fibre-optic photometric sensors, resistivity probes, resistivity tomography, and copper ion-selective electrodes. Methods of image analysis, signal processing techniques and multi-spectral image analysis were also explored and applied to images of moving plumes. In addition, an optical technique for detecting NAPL by cone probe was investigated. Their relative merits are discussed. This work was conducted as part of an EU-funded network programme: NECER (Network of European geotechnical Centrifuges for Environmental Research), and this paper summarises the conclusions of the sensors and imaging working group.
Shaking table testing of geotechnical models
Authors: Wood David Muir , Crewe Adam , Taylor Colin
Published: November 2015

Shaking tables provide one means of obtaining data from physical models of geotechnical systems under simulated earthquake loading. While there may be challenges in ensuring exact scaling of all aspects of a geotechnical system between prototype and model, the large size of the shaking table models does give a good basis for validation of numerical modelling strategies.

A shear stack provides a means of creating a mass of soil which can approximate the free field of the real world. Observations of the performance of the Bristol shear stack are presented and compared qualitatively with patterns of behaviour observed in laboratory simple shear tests. The results of some tests on model gravity retaining walls performed using the shear stack are used to show the relevance of simple models of geotechnical system performance and to illustrate the difficulty of correlating system performance with individual parameters of input time histories.
Optical measurement of deformation using transparent silica gel to model sand
Authors: Iskander Magued G. , Sadek Samer , Liu Jinyuan
Published: November 2015

This paper addresses an important and critical need in geotechnical engineering. There are no established methods to measure three-dimensional deformation patterns and flow characteristics within a soil mass. As a result, it is difficult to analyze complex soil-structure interaction and ground flow problems. Measurement of three-dimensional deformation patterns and flow characteristics within a soil continuum are usually limited by the fact that soil sensors do not provide a continuous image of the measured continuum. Additionally, soil sensors exhibit static and dynamic characteristics that are different from those of the surrounding soils, and therefore can change the response of the measured continuum. The fundamental premise of this research is that tests conducted with a transparent material with geotechnical properties similar to those of natural soils can circumvent these experimental problems if the response of a model transparent continuum can be measured using non-intrusive optical visualization techniques. This paper presents the geotechnical properties of a new family of transparent materials made of silica gels, which are suitable for modeling the geotechnical properties of sand. A new imaging technique that makes uses of the developed material in measuring spatial deformations in transparent soil models is also presented.
Centrifuge tests on the failure of dikes caused by uplift pressure
Authors: Allersma H.G.B. , Rohe A.
Published: November 2015

A series of centrifuge tests has been earned out to investigate the behaviour of dikes under uplift conditions. Particular attention has been paid to clay dikes that are founded on a permeable layer of sand. A rising water level in the river causes an overburden pore water pressure underneath the clay layer, resulting in a reduction of friction between the sand and the clay layer, which can lead to failure of the dike. Although the principle of the mechanism is known, very little was known at what conditions failure occurs. A test set-up has been developed to model a complete system including riverbed and hydraulic gradient in the sand layer. The groundwater flow has been manipulated by adapting sand layers consisting of different types of sand. Points of research are the determination of length and location of the uplift zone and the influence of material and geometrical parameters. The effects of berms and ditches and the combination of them have been studied as well. In order to study in particular the behaviour of the uplift zone the horizontal driving force of the embankment is simulated by a mechanical loading system (bulldozer tests). A comparison is made between the centrifuge tests and analytical and numerical calculations using a finite element program. The centrifuge tests are compared qualitatively with the results of a field test. The tests have led to a better understanding of the failure mechanism of dikes founded on sand layers.
Centrifuge modelling of liquefaction and lateral spreading of virgin, overconsolidated and pre-shaken sand deposits
Authors: Sharp Michael K. , Dorby Ricardo , Abdoun Tarek
Published: November 2015

This paper presents the results of five centrifuge model tests of earthquake-induced liquefaction and lateral spreading in sand using a laminar box. These centrifuge experiments simulate a gently sloping, H = 6 m thick stratum of saturated homogeneous sand of infinite lateral extent and relative densities of 45% and 75%. While four of the tests were conducted at a centrifugal acceleration of 30 g, the fifth experiment was a “model-of-the-model” verification at 50 g. Each deposit was subjected to the same lateral base shaking having a prototype peak acceleration of approximately 0.2 g, frequency of 2 Hz, and duration of about 22 cycles. In all models the soil was saturated with a viscous fluid such that under the increased gravitational field the deposit had the prototype permeability of fine-grained sand. Detailed discussions and comparisons of the five centrifuge tests are included. In two of the models, the sand was respectively overconsolidated (overconsolidation ratio, OCR = 4) and pre-shaken, in order to study the effects of these factors on liquefaction and lateral spreading; neither the pre-shaking nor the overconsolidation changed much the density of the soil. The study of effects of sand relative density, overconsolidation and pre-shaking is performed by comparison of three key measured parameters: thickness of liquefied soil Hl permanent lateral displacement DH, and ground surface settlement S. It is found that either overconsolidation or pre-shaking of 45% relative density sand reduces Hl DH and S as much as increasing the relative density of the soil to 75%. In addition, comparison with three similar centrifuge tests reported elsewhere which modeled a 10 m thick stratum of virgin sand, allows evaluation of the influence of deposit thickness. It is found that increasing the deposit thickness increases Hl, DH and S.
Development of combined loading apparatus for centrifuge test
Authors: Punrattanasin Pongsakorn , Nishioka Hidetoshi , Murata Osamu , Kusakabe Osamu
Published: November 2015

This paper presents the design, mechanism and performance of a combined loading apparatus that has been jointly developed at The Tokyo Institute of Technology and the Railway Technical Research Institute of Japan for centrifuge tests. The unique feature of the test system developed is that any combination of load and displacement path of combined vertical (V), horizontal (H) and moment (M) load can be generated and directly applied to model footing. The combined load, displacement and rotation can be accurately achieved by a feedback system that controls three loading jacks and three servo motors. The Cambridge-high performance contact stress transducer was customarily designed and placed into the system in order to evaluate the loads acting on the model footings. A set of LVDTs is also positioned to measure the movement of footings. The primary aim of the development of this system was to observe the footing behavior in V-H-M load and displacement space. The apparatus was first used to evaluate the performance and effectiveness of the new composite structure of shallow foundation and sheet pile called “sheet pile foundation”. The test results confirmed the expected performance of the newly developed loading apparatus.
Ground movements and collapse mechanisms induced by tunneling in clayey soil
Authors: Wu B.R. , Lee C.J.
Published: November 2015

A series of centrifuge model tests of unlined single and parallel tunnels was carried out in the plane strain condition to investigate the ground movement and the collapse mechanisms induced by tunneling in clayey soil. The measured surface settlement trough due to single tunneling was first fitted by a normal probability curve. Afterwards, a superimposition method with modification factors was suggested for estimating the surface settlement troughs induced by parallel tunneling with various center-to-center distances. The relationships of surface and subsurface settlement troughs versus the ground losses were then proposed as a function of the burial depth of the tunnel. The prediction methodology of settlements based on the ground loss was verified by comparison with 12 sets of monitored field data. The collapse mechanisms of the single and parallel tunnels derived from the upper-bound theory of plasticity were correlated with the observed ground movements in the model tests.
Uplift performance of FRP tapered piles in dense sand
Authors: Sakr M. , El Naggar M. H. , Nehdi M.
Published: November 2015

The influence of taper angle on the uplift performance of FRP tapered piles in dense sand at various embedment ratios is investigated using a large-scale testing facility (pressure chamber). The current study evaluates the uplift performance of tapered piles relative to the uplift performance of straight-sided wall piles. Thirteen pile installations were performed in a pressure chamber using conventional head driving and a novel toe driving technique. Twenty­six uplift load tests were performed at different radial and vertical confining pressures in order to simulate pile segments at different depths. The results of uplift loading tests are presented and discussed. The results showed that the uplift capacity of tapered piles is slightly higher than that of cylindrical piles with similar average diameter and length. The taper effect on the pile uplift performance is evaluated using the uplift taper coefficient. A hyberbolic relationship is established between the uplift load and displacement that can be used to determine the soil stiffness for use in non­linear analysis. A simplified design approach for uplift capacity of tapered piles is discussed and evaluated.
Physical modelling of dynamic behavior of soil-foundation-superstructure systems
Authors: Kutter Bruce L. , Wilson Daniel W.
Published: November 2015

The goal of this paper is to promote the concept of testing centrifuge models that include soil-foundation-superstructure systems. Civil engineering research and practice is often compartmentalized, with structural engineers assuming very simplified foundation behavior, and geotechnical engineers assuming very simplified superstructure behavior. Only in rare cases does a bridge or building designer take account of energy dissipation through foundation yielding. Geotechnical engineers typically design foundations that meet minimum required capacity and stiffness specifications; they do not design foundations that optimize system performance. Large scale centrifuge models offer a unique capability to produce experimental data regarding seismic performance of soil-foundation-superstructure systems. In the centrifuge realistic models of buildings and bridge superstructures can be supported on realistic models of foundations with realistic soil behavior. Soil-foundation-superstructure systems have modes of behavior that are not present in experiments on individual foundation or superstructure components. Examples of two recent series of centrifuge tests demonstrate that system tests are possible and that unique data may be obtained. A spin-off benefit of soil-foundation-superstructure system model tests is the inevitable cross-disciplinary collaboration between structural and geotechnical engineers. It is suggested that this may eventually contribute to an evolution of design philosophy that is based more directly on system performance, with less focus on minimum component specifications.
Evaluating the saturation of model ground by P-wave velocity and modelling of models for a liquefaction study
Authors: Takahashi Hidenori , Kitazume Masaki , Ishibashi Shinji , Yamawaki Shuuji
Published: November 2015

A substantial amount of experimental and analytical research has been carried out on the liquefaction mechanism, prediction of liquefaction, and soil improvement for liquefaction. In model tests on liquefaction phenomena, several techniques have been proposed for preparing saturated sandy ground. The vacuum method and CO2 gas have been used for saturation by many researchers. There have been few investigations that have studied the effective of this and alternative methods to achieve saturation of the sand in centrifuge model tests. In the present study, model sandy ground was prepared by three techniques and their degrees of saturation were estimated by measuring the P-wave velocity propagating through the ground. The degree of saturation of model ground was greatly influenced by the preparation technique. Further, the reliability and repeatability of centrifuge model test must be carefully examined to conduct successful tests, because the measurements are influenced even by slight differences in preparation of model ground. In the present study, a modelling of models test using three different scaled models (1110, 1/25, and 1/50) was performed to investigate the reliability of our centrifuge model test for liquefaction phenomena. The results confirmed good agreement of the measurements in all test cases.
Centrifuge scaling laws for guided free fall events including rockfalls
Authors: Chikatamarla R. , Laue J. , Springman S. M.
Published: November 2015

Concrete protection galleries are generally used in mountainous regions to protect the local infrastructure and lifelines against potential impacts from rock boulders. These can be protected further by carefully designed cushion systems, most of which rely on granular geomaterials. Rockfall impact energies can reach magnitudes of the order of millions of Joules, requiring understanding of the combined energy absorption mechanisms at high energy levels for improved design of the gallery and cushion. These prototype high-energy ranges can be achieved at the laboratory scale with the help of a geotechnical centrifuge. The model is rotated under high g levels, thereby increasing the unit weight of the material. Prototype energy levels can be represented in a small scale model with consideration of appropriate scaling laws, and although free fall events in a centrifuge experience components of the Coriolis acceleration, projectiles (boulders) will move out of the centripetal gravity field when losing contact with the rotational field. A guiding tube is used in this case to keep the boulder in the acceleration field (ng) in order to achieve sufficient input energy levels to represent existing design criteria. The change in the g-level during the fall of the boulder in the centrifuge, due to the change in the radius, has to be taken into account for determination of the impact energy. In this case, direct application of traditional scaling laws for centrifuge modelling is invalid. This paper focuses on the determination of the change in the g field with time during the fall of the boulder to estimate the g level at the time of impact and this value is used in the calculation of the prototype energy levels. A summary of the performance of various cushion materials is given.
The behaviour of piles undergoing a change in lateral loading direction
Authors: Levy Nina H. , Gaudin Christophe , Einav Itai
Published: November 2015

Pile foundations installed for offshore applications or in earthquake prone areas must be designed to withstand transient static and cyclic lateral loads that may occur in different lateral directions at different times. Research has chiefly been devoted to studying the behaviour of a pile subjected to one dimensional lateral loading and the influence of changing the lateral direction of this loading has not been widely considered. This paper presents the results from a series of centrifuge tests which involve multi-stage loading of a pile, considering changes in loading direction. The behaviour of a pile subjected to an unload-reload loop in a single direction is compared to that of a pile reloaded at 90° to the initial loading direction. When piles are reloaded at 90°, the set of rules that apply to one dimensional reloading become ineffective because an ‘effect of recent loading history’ governs the behaviour. In particular, local hysteresis loops are widened and the global instantaneous stiffness varies. These experimental findings are in accord with predictions from a simple numerical model, which defines the soil surrounding a pile using a series of two­dimensional elastoplastic Winkler models along the pile length.
Catalogue of scaling laws and similitude questions in geotechnical centrifuge modelling
Authors: Garnier J. , Gaudin C. , Springman S.M. , Culligan P.J. , Goodings D. , Konig D. , Kutter B. , Phillips R. , Randolph M.F. , Thorel L.
Published: November 2015

Some forty years ago, when geotechnical centrifuge modelling had been rediscovered and was being developed once more after the early work of Phillips (1869), only a few studies were devoted to the questions and concerns about scaling laws and similitude conditions. During the first decades, it was relatively easy for researchers to keep themselves informed about the main outcomes of these studies and to take them into account when designing new centrifuge model tests. This is obviously not true today following the welcome growth in terms of the large number of centrifuge facilities now in operation around the world. It is increasingly difficult, but yet absolutely essential, to know about the relevant developments concerning studies into the scaling laws and, furthermore, into the limits of the domains of the use of centrifuge modelling. On the other hand, new media offers a significant opportunity to provide this resource to the physical modelling community.

New topics are investigated by many researchers as they become more inventive in the ways in which geotechnical centrifuge modelling is applied to solve pressing problems within geotechnical engineering, and across other disciplines too. Innovative work presenting comparisons between centrifuge model tests and true scale tests are providing original data on the validity of the scaling factors.

During the TC2 meeting at St John’s (Canada) in July 2002, the first author, J. Garnier (LCPC), suggested making an inventory of the scaling laws and similitude questions relating to centrifuge modelling. The aim of this catalogue is to present the questions already solved (with inclusion of the references of the papers where the results have been presented) and the unsolved problems (on which research should continue).

The first draft of this catalogue is now available and it is hoped that it will become a useful tool for scientists and researchers involved in centrifuge modelling. Of course, this catalogue will be regularly updated, every four years during the International Conferences on Physical Modelling in Geotechnics. The latest version of the catalogue is available on the TC2 website ( www.tc2.civil.uwa.edu.au ).
Apparatus for centrifuge modelling of top down basement construction with heave reducing piles
Authors: McNamara A.M. , Goodey R.J. , Taylor R.N.
Published: November 2015

The construction of deep basements in urban areas is associated with many risks and problems among Which is the possible damage to existing structures and services resulting from settlements near the excavation. A number of methods are routinely employed to attempt to control these movements (e.g. top-down construction, use of stiff diaphragm walls). This paper discusses the methodology and practicalities of a series of centrifuge model tests designed to investigate the effect of deep basement construction. Two sets of experimental apparatus are described in detail and their effectiveness in terms of robustness and generation of repeatable data are assessed. It is shown that using relatively simple techniques and equipment it is possible to model many of the features associated with top-down construction.
Centrifugal modelling of rockfall events
Authors: Itoh K. , Toyosawa Y. , Kusakabe O.
Published: November 2015

Rockfall, and its subsequent motion down the slope, often poses a serious hazard for people and infrastructure. This paper describes the development of a rockfall generation system used to investigate the rockfall behaviour and dynamic process of the overall trajectory in centrifuge model tests. Firstly, the experimental results are compared with the theoretical movement of a free fall event under the hypothesis that this occurs fully in a rotational acceleration field. Secondly, a series of centrifuge model tests were performed to observe the movement of falling boulders, which exhibit various falling modes: free falling, bouncing, rolling or sliding, sometimes associated with fracturing during the falling process, which is not taken into account in most numerical simulations. In order to investigate the influence of a boulder fracturing on the falling velocity and bouncing height, tests were carried out using different parameters for boulder material (stiffness and shape), with the trajectory measurements of the falling boulder captured by a high­speed video camera. The test results revealed that the falling velocity, and the bouncing height in the case of fractured boulders, were larger than those for rolling ones (unfractured).
Incineration of wastewater sludges
Authors: Tebbutt T H Y
Published: November 2015

After a somewhat chequered history in the UK, wastewater sludge incineration is currently seeing a resurgence of interest. The Paper reviews the effects of recent environmental legislation on sludge production and disposal routes, and places the role of incineration in this new context. The characteristics and performance of the main types of sludge incinerator are discussed, and the importance now given to emission control and safe disposal of residues is emphasized. Incineration of wastewater sludges is now a viable option for some situations although its capital cost is still higher than other options. It does, however, offer a security which other disposal routes cannot offer.
Effect of fineness in clinker-calcined clays-limestone cements
Authors: Vizcaíno Andrés Leng M. , Antoni Mathieu Georges , Alujas Diaz Adrian , Martirena Hernández José Fernando , Scrivener Karen Louise
Published: November 2015

This paper looks at the effect of fineness of the different components in a blend containing 55% Portland cement, 30% calcined clay and 15% limestone. The calcined clay originates from a natural deposit in Cuba and contains less than 50% kaolinite. The particle size distribution (PSD) of each of the three components was varied by using different grinding times, and the consequences on heat release, strength development, pore structure and phase assemblage development were investigated up to 28 d. Higher fineness of both clinker and calcined clay can considerably improve compressive strength at all ages, while limestone fineness only plays a role at early age. The formation of carboaluminate hydrates owing to the combined addition of calcined clays and limestone is confirmed for this case of a mixed clay with moderate kaolinite content.
Synthesis of low-energy cement based on α-C2SH
Authors: Siauciunas Raimundas , Baltakys Kestutis , Gendvilas Rokas , Prichockiene Edita
Published: November 2015

In this study, parameters of α-C2SH synthesis from limestone and quartz sand were determined and compressive strength values of the hydraulic cementitious binder, manufactured on its basis, were established. The results show that slow hydrothermal reactions in the calcium oxide–quartz–water system can be intensified using sodium oxide additive. In this case, α-C2SH was already the dominant compound in the product after 8 h of hydrothermal synthesis at 200°C in stirred suspensions. It was found that tribochemical activation must be combined with thermal treatment in order to obtain a hydraulically active cementitious binder from the mixture of synthesised α-C2SH and quartz sand. The heat flow value of such binding material during its main hydration reaction varied from 0·0019 W/g to 0·0028 W/g when the temperature of the thermal treatment was increased from 400°C to 450°C. Strength measurements showed that the addition of sieved quartz sand increased the compressive strength of the mortars, compared with a pure hydraulic cementitious binder, from 10·3 MPa to 13·5 MPa after 3 d, from 12·9 MPa to 16·7 MPa after 7 d and from 19·4 MPa to 22·5 MPa after 28 d of hydration.
Synthesis of block polycarboxylate copolymer and its application in a cement system
Authors: Ran Qianping , Wang Xiumei , Jiang Jiang , Yang Yong
Published: November 2015

The sequence structure of polymers plays an important role in determining their performance. However, existing polycarboxylates mostly have a broad molecular weight distribution and the sequence structure is randomly distributed. In this work, a novel water-soluble block copolymer made of poly(ethylene glycol) methyl ether methacrylate (OEGMA) and acrylic acid (AA) was designed using reversible addition-fragmentation chain transfer polymerisation. Structural information of the block polycarboxylate was characterised by gel permeation chromatography and proton nuclear magnetic resonance. The effects of molar ratio of AA to OEGMA on flowability, zeta potential and adsorption in cement paste were studied. It was proved that polycarboxylate with a block distribution could be successfully applied as a superplasticiser. Furthermore, the length of the two blocks in the block distribution influenced the zeta potential and adsorption of the superplasticiser onto cement particle surfaces, and thereby the workability of cementitious materials. The knowledge gained from this work may be used in the design of superplasticisers for optimal performance in some specific applications.
Reactive powder concrete reinforced by nanoparticles
Authors: Long Guangcheng , Shi Ye , Ma Kunlin , Xie Youjun
Published: November 2015

The influences of four nanoparticles of nanosilica (SiO2), nano-calcium carbonate (CaCO3), nano-aluminium oxide (Al2O3) and nano-iron oxide (Fe2O3) on workability, hydration, pore structure and mechanical strength of reactive powder concrete (RPC) are investigated by macro/microscopic methods. The aim of this study is to provide an essential basis for exploiting new-generation cementitious materials with ultra-high strength and super-long service life by employing modern nano-modification technology. The results indicate that addition of low-dosage nanoparticles to RPC shows a remarkable influence on the mechanical strength, hydration and pore structure compared to the ordinary cement system with a relatively high water/cement ratio. The compactness and mechanical strength of RPC can be greatly improved by incorporating nanoparticles. The promotive ratio of flexural and compressive strength of RPC is up to 30%. The elevated temperature further promotes the effect of nanoparticles on the strength of RPC. The seeding effect of nanoparticles on hydration of cement and the nano-size filling role are strengthened in the RPC system.
Instrumentation and early-age monitoring of concrete slabs
Authors: Austin Simon A. , Robins Peter J. , Bishop Jonathan W.
Published: November 2015

This paper reports the instrumentation and monitoring techniques developed to improve understanding of the early-life behaviour of concrete industrial ground-floor slabs. Concrete strains, temperatures and joint movements were measured using vibrating-wire embedment strain gauges and thermistors, while ambient conditions were monitored to assess their effects. A reliable, accurate and easy-to-implement methodology, developed by instrumenting four types of floor slab (mesh-reinforced long strip, mesh-reinforced jointed large area pour, steel fibre-reinforced jointed large area pour and steel fibre-reinforced jointless large area pour) is described in detail, along with the further developments and modifications to the instrumentation. The methodology developed would be equally applicable to the early-life monitoring of other concrete structural elements. Some sample results of data gathered using the instrumentation methodology developed are included.
How Athens’ Olympic stadium was finally pulled together
Authors: Siriani Federico , Di Silverio Massimo
Published: November 2015

Completing the dramatic 18 500 t main stadium roof for the 2004 Athens Olympics was tension engineering in every sense. The 304 m long, 80 m high cable-stayed steel and polycarbonate roof designed by Santiago Calatrava was literally pulled together at the last minute, just as it was on the verge of being abandoned. This paper describes how the two sinuous halves of the roof were built 70 m away from each side of the existing 20-year-old stadium, using a series of strand-jack towers, and then how they were drawn together using a strand-free pulling system devised at the eleventh hour. The final pull was completed on 6 June, just four days before the first test events. It is a timely reminder of the huge challenges that engineers invariably have to overcome in delivering monumental sporting arenas on time.
Geothermal energy: a major renewable energy resource
Authors: Batchelor Tony
Published: November 2015

Geothermal energy—which covers all forms of heat extracted from the earth—has been used on a commercial scale for over 100 years. The resource is available in one form or another in every country and can provide base-load electricity and heat on a continuous and sustained basis. More than 70 countries now exploit geothermal resources, the global scale of which means they do not suffer depletion in the same way as more finite mineral resources. This paper reviews the various forms of geothermal energy production currently in operation and planned around the world. It concludes that geothermal energy has potential for further substantial growth and can make a large contribution to reduction of greenhouse gas emissions, particularly in developing countries.
On the ropes: civil engineers get closer to rail bridges
Authors: James Chris
Published: November 2015

Bridges and viaducts are an essential part of transport infrastructure, particularly on railway networks where the variety of structural type, size and age usually exceeds that of the highway network. Inspection and examination form a large part of the management of these structures, which are often high and in remote locations. This paper details how rope-access techniques are being increasingly used for the inspection of such structures in the UK and argues the benefits for more civil engineers to be trained in rope-access work.
Static equilibrium bays in coast protection
Authors: Herrington Simon P. , Li Bin , Brooks Simon
Published: November 2015

As part of the 2004 Hythe to Folkestone Harbour coast protection scheme, two static equilibrium bays were formed using rock headland structures and shingle imported as part of the beach renourishment phase of the scheme. The development of this element of the scheme and the appraisal process that led to these bay forms being chosen as the most appropriate form of coast protection are discussed. The performance of the bays has been continually monitored since their construction and the measured plan-shape of each bay has been compared with the theoretical predictions. This has shown that there is good agreement between the crenular plan forms predicted by the mathematical models and the theoretical methods, which are founded on the log-spiral curve that has been shown to represent the crenular plan form of naturally formed bays. Observations based on the survey data collected over the 20 months since the completion of the scheme have shown that the measured plan form is in relatively good agreement with the theoretical predictions. The bays do, however, exhibit distinct yet small differences from the theoretical form, but nevertheless are approaching an equilibrium state.
Wind-generated interaction between tall buildings
Authors: Kim Young-Moon , You Ki-Pyo , Ko Nag-Ho
Published: November 2015

To investigate the effect of aerodynamic interference that could increase the dynamic responses of tall buildings to wind loads, a wind tunnel experiment using high-frequency force-balance was conducted to estimate acceleration responses. Root mean square (r.m.s.) acceleration responses of along-wind, across-wind and torsional wind directions and peak resultant accelerations were estimated with and without consideration of the effect of aerodynamic interference, and were then compared with each other. When the effect of aerodynamic interference was included, r.m.s. torsional acceleration response was increased by 82%. For peak resultant acceleration response, the maximum increase was 69%. It was found that dynamic responses could be increased when considering the effect of aerodynamic interference.
Guide to drawdown capacity for reservoir safety and emergency planning
Authors: Gosden John , Dutton Thomas , Hart Dave
Published: November 2015

A key factor in avoiding and minimising the impact of catastrophic dam failure is the ability to draw a reservoir down in the event of an emergency. In the UK there is currently no single accepted approach to determining what represents an acceptable rate of reservoir drawdown. A project is therefore currently being carried out, under the joint Environment Agency/Defra (Department for Environment, Food and Rural Affairs) Flood & Coastal Erosion Risk Management (FCERM) research and development programme, to research and produce guidance on the drawdown capacity required for reservoir safety. This paper summarises some of the research findings from stage 1 of this project and sets out the proposed approach to develop the guidance in the next stage of the project.
Implications of underground access for shale oil and gas extraction on dam safety – a risk assessment
Authors: Brown Alan , Claydon Jim
Published: November 2015

The Department of Energy and Climate Change (DECC) carried out a consultation in 2014 on proposals to change the regulatory framework such that ‘Companies would have right of access to all land more than 300 m below the surface’ for extraction of shale oil and gas, and geothermal energy with no need for landowner consultation consent. This paper considers the risks to dam safety from uncontrolled access to land more than 300 m below the surface, where directly below or in the proximity of dams. The paper concludes with a discussion of mitigation measures that could be adopted to manage this risk, and ensure the continuing safety of the UK stock of dams.
BDS conference in Belfast September 2014
Authors: Butterworth Jonathan D
Published: November 2015

The 18th biennial conference of the British Dam Society (BDS) took place at Queen's University, Belfast, with tours to several reservoirs. The conference banquet and Binnie lecture took place in Titanic Belfast. A pre-conference tour to Lagan weir was held, and this is reported upon separately. The Accompanying Persons programme also ran in parallel throughout the conference.
Methodology for the sustainability assessment of facades
Authors: Vega Ruth
Published: November 2015

Nowadays, there are many tools and methodologies designed to measure the sustainability of buildings. Few of them, however, allow for an isolated assessment of the building systems themselves as components of the entire building. A methodology for assessing the sustainability of building systems, considered in relation to the whole building, will allow manufacturers to assess the sustainability of manufactured components in order to improve their performance. Additionally this will help designers to specify construction arrangements in the early stages of the design. This paper presents the systematisation of a comparative analysis of facade building systems and includes the development of a new methodology that can serve as a basis for carrying out quantitative and qualitative comparisons of the sustainability of industrialised building systems in facades. The methodology is associated with a tool that allows for measuring, assessing and rating the levels of sustainability of the industrialised facades employed in residential buildings. The evaluation is based on ensuring that sustainability criteria are met. It involves an approach to sustainable industrialisation of construction with regard to energy conservation and natural resources, the reuse of these resources and life-cycle management of the materials and components.
Towards the sustainability of road transport through the introduction of AV technology
Authors: Hardy Ben , Fenner Richard A
Published: November 2015

The paper investigates the potential for level 2 autonomous vehicle technology to improve four prevailing sustainability issues specifically on highways: high congestion levels, increasing accident rates, high carbon dioxide emissions and poor journey time reliability. Cooperative adaptive cruise control shows potential to achieve high-volume cooperative driving on highways by controlling these parameters and forming vehicle platoons. Accident rates, carbon dioxide emissions and journey times can be reduced as a result. The risks of platooning are discussed and a minimum safe platoon headway is established to mitigate the risk of vehicle platoon collisions. This headway is applied to a real highway case study, demonstrating the potential to increase notional highway design capacity from 3600 vehicles per hour (vph) to 9213 vph, with significant sustainability improvements possible. Recommendations are made to complete a number of policy implementation and technology development tasks aimed to create the best chance of achieving the identified sustainability benefits within a 20-year timeframe.
Greenhouse gas considerations in rail infrastructure in the UK
Authors: Saxe Shoshanna , Casey Gerard , Guthrie Peter , Soga Kenichi , Cruickshank Heather
Published: November 2015

Transportation-related greenhouse gas (GHG) emissions account for an increasing proportion of total emissions in the UK and globally. The provision of rail transit is popularly proposed to reduce transport GHG emissions, but the provision of new infrastructure is itself GHG intensive. Understanding of the GHG emissions impact of rail projects is limited and very few longitudinal studies have been carried out. Existing assessments are often limited both in their scope and the factors considered. A holistic understanding of GHG impacts must include an assessment of capital GHG emissions, operational energy and maintenance as well as an assessment of ridership mode shift and mode share impacts and the relationship between transit infrastructure and land use. This paper explores rail infrastructure projects and their associated GHG emissions. Guidance is given on the aspects of rail planning, design and construction that must be considered to more fully understand the associated GHG impacts.
Strength tests of enzyme-treated illite and black soil mixtures
Authors: Khan Tanveer Ahmed , Taha Mohd Raihan , Firoozi Ali Asghar , Firoozi Ali Akbar
Published: November 2015

Enzymes are organic degradable materials, recently introduced as soil improvement additives for earthen pavement layers and embankments. This study was conducted to evaluate the effect of three enzymes on the unit weight and unconfined compressive strength of illite mixed with black soil. The optimum moisture content (OMC) and maximum dry density of the untreated soil were determined with a standard Proctor test. The same test was conducted to prepare untreated and treated soil samples at OMC. Samples were prepared for two dosages and two curing periods. However, no considerable increase in unit weight was observed for specimens treated with the three enzymes. Larger-sized soil samples were prepared to reduce the inaccuracy in sample preparation and testing. No noticeable improvement was observed for any of the enzymes and dosages. Some of the samples showed a little increase in strength but that was found to be due to the higher densities of those samples. A Fourier transform infrared spectroscopy test was executed to investigate the structure and functional groups of the three enzymes and their effect on soil. Thermogravimetric analysis, differential thermal analysis and X-ray diffraction tests were performed to determine whether any chemical reaction took place between the soil and the enzymes, but no chemical reactions were observed.
Do smart cities realise their potential for lower carbon dioxide emissions?
Authors: Cavada Marianna , Hunt Dexter V.L. , Rogers Chris D.F.
Published: November 2015

‘Smart cities’ embrace technologically based solutions as an enabler of efficient, affordable and more sustainable urban living in times of resource scarcity, persistent austerity and high-tech innovations. However, cities’ evermore complex systems are, albeit unwittingly, causing mismanagement, future uncertainty and lack of transparency to exacerbate their challenges. Climate change is likely to be the greatest of the contextual challenge scale and in terms of scale and diversity of impacts. This paper explores the role of smartness indicators, in which ‘green’ undoubtedly is a large innovation engine, yet not the only one. Similarly, the beneficial impacts of ‘green’ technology solutions are yet to be fully understood or rigorously established. Cities that adopted smart roadmaps embedded lower carbon dioxide (CO2) emissions within the environmental sustainability agenda; however, the degree to which the two issues have been directly linked is unclear. Findings from this study suggest that lower carbon dioxide emission initiatives are embodied within the environmental sustainability initiatives agenda, yet are not clearly defined in the smart cities ideology. This paper proposes a balanced combination of human talent, ‘green’ innovation and technological innovation – the interdependent triptych philosophy for ‘smart city’ resilience that can be adapted and offer tailored solutions for cities, communities and individuals.
Method to increase seam efficiency for woven geotextile materials
Authors: Guo W. , Chu J. , Zhou B.
Published: November 2015

Permeable geotextile tubes are usually made by sewing geotextile sheets together and then filling with clay slurry or sand. However, the tensile strength of a seamed woven geotextile material is usually only half of that of the seamless geotextile sheet. A new seam method has been proposed to improve the tensile strength of the seamed woven geotextile material. The main idea of the method is to reinforce the geotextile on the area of the pin-hole side which was the weakest part in the traditional seaming methods. The test results show that after the seam had been reinforced, the percentage ratio of its tensile strength to the strength of seamless geotextile sheet was improved by more than 75%.
The application of water-absorbing geocomposites to support plant growth on slopes
Authors: Lejcuś K. , Dąbrowska J. , Garlikowski D. , Śpitalniak M.
Published: November 2015

The study presents the results of experiments with a new type of water-absorbing geocomposite and its influence on the strength of biotechnological protection. The geocomposite influences the increase of water retention in soil and the improvement of the conditions of plant vegetation. The increase in the shearing strength of roots reached 66.7% for shrubs and 20.1% for grass. Increased growth of the root system and the above-ground parts of both shrubs and grass was noted.
Experimental investigation of dynamic porewater pressure response induced by single shallow-buried detonations in saturated sand
Authors: Wang W. , Chen Y. , Liu H. , Zhou F.
Published: November 2015

Studies on the dynamic porewater pressure response induced by single shallow-buried detonations in saturated sand are limited. A series of single shallow-buried detonation tests was conducted in a large pit filled with saturated sand. The objective of the tests was to study the influence of charge weight and burial depth on porewater pressure generation. Comparisons of excess porewater pressures obtained from the tests and previous liquefaction studies on fully contained explosions are presented. For a given cube-root scaled distance, the excess porewater pressure ratio (PPR) induced by a shallow-buried detonation is much lower than that of a fully contained explosion. The burial depth of the explosive, which is not considered in previous empirical formulas, is a significant parameter in addition to the scaled distance. A modified empirical model as a function of the scaled burial depth and other conventional factors is proposed and shown to provide valuable information for predicting the PPR induced by single shallow-buried explosions in saturated sand.
Optical quantification of suffosion in plane strain physical models
Authors: Ouyang M. , Takahashi A.
Published: November 2015

Suffosion is a seepage-induced instability phenomenon whereby fines are eroded away through the constrictions formed by coarse particles, resulting in a reduction in soil volume and a change in hydraulic conductivity. In this study, upward seepage tests were performed on gap-graded soil containing coloured fines in a plane strain apparatus. A series of images was recorded through a transparent window to quantify the features of suffosion. The estimated cumulative eroded soil mass from image analysis was found to generally agree with independent macroscopic observations, indicating that optical analysis allows an easy identification of suffosion characteristics. For the tested soil, the fines were prone to be transported within an instant period of increasing hydraulic gradient, with few of them moving during the constant flow. Furthermore, the volume of the specimen was reduced due to suffosion, leading to an alternation of preferred coarse particle orientations in the observation field.