bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of geocomposite drain against rapid-drawdown loading for roller-compacted concrete (RCC) armored earth dam
Authors: Özer A.T. , Bromwell L.G.
Published: November 2015

ABSTRACT: This case study describes the design and construction of a drainage system consisting of a geocomposite drain immediately beneath the roller-compacted concrete (RCC) slope facing at the Loxahatchee Reservoir in western Palm Beach County, Florida. 1.5 kilometers of RCC and geocomposite drain were installed along the western alignment of Cell 6. The main stability issue for the RCC was the development of excessive pore water pressure beneath the RCC in the event of rapid drawdown of the reservoir. Transient seepage analysis showed that installation of the geocomposite drain eliminated excess pore pressure beneath the RCC and dramatically increased the factor of safety against uplift, preventing structural instability of the RCC. Under the operational reservoir levels since placing the reservoir in operation, no structural instability has been observed in the RCC, which was also confirmed by post-construction transient seepage analysis. Performance of the geocomposite drain has successfully met the design objectives.
Estimation of Dynamic Interfacial Properties of Geosynthetics
Authors: De A. , Zimmie T.F.
Published: November 2015

The dynamic frictional properties of different geosynthetic interfaces play an important role in the stability analyses of various geotechnical structures that incorporate geosynthetics. The paper presents and discusses laboratory test results on eight different interfaces, formed through various combinations of three geosynthetics (a geotextile, a smooth geomembrane, and a geonet). The dynamic frictional properties were estimated using cyclic direct shear tests, shaking table tests conducted at a normal g-level of 1g as well as at high g-levels, and on a 100 g-ton geotechnical centrifuge. The centrifuge simulated high normal stress levels, commonly encountered by geosynthetics comprising base liners of landfills or base isolators for large structures. The tests revealed various important characteristics regarding the dynamic frictional properties of the geosynthetic interfaces, including a dependence of some of the interfaces on the level of normal stress and the excitation frequency. It is felt that these differences should be considered when selecting proper test methods in relation to the application for which the geosynthetic is considered. It was concluded that proper simulation of field conditions in laboratory experiments is important to obtain suitable friction angle values to be used in design.
Permeability and stiffness of sands at very low effective stresses
Authors: HAIGH S.K. , EADINGTON J. , MADABHUSHI S.P.G.
Published: November 2015

Loose saturated sandy soils may undergo liquefaction under cyclic loading, generating positive excess pore pressures due to their contractile nature and inability to dissipate pore pressures rapidly during earthquake loading. These liquefied soils have a near-zero effective stress state, and hence have very low strength and stiffness, causing severe damage to structures founded upon them. The duration for which this near-zero effective stress state persists is a function of the rate of reconsolidation of the liquefied soil, which in turn is a function of the permeability and stiffness of the soil at this very low effective stress. Existing literature based on observation of physical model tests suggests that the consolidation coefficient Cvassociated with this reconsolidation of liquefied sand is significantly lower than that of the same soil at moderate stress levels. In this paper, the results of a series of novel fluidisation tests in which permeability k and coefficient of consolidation Cvwere independently measured will be presented. These results allow calculation of the variation of stiffness E0and permeability k with effective stress. It is shown that while permeability increases markedly at very low effective stresses, the simultaneous drop in stiffness measured results in a decrease in consolidation coefficient and hence an increase in the duration for which the soil remains liquefied.
Effect of Again of the Shear-Strength Properties of a Normally Consolidated Clay
Authors: Bjerrum Laurits , Lo K. Y.
Published: November 2015

Synopsis

In the Paper is described a series of triaxial tests on samples which were normally consolidated for different periods of time prior to the subsequent shear test. It is shown that the behaviour of the clay when sheared depends on the “age” of the samples. With time the clay becomes more brittle with smaller failure strains and the undrained shear strength shows a slight increase. A study of the stress-strain curves leads to the conclusion that the effect of time can be explained by the growing of cohesive bonds at the contact points between the particles. The cohesive bonds lead to a greater resistance against a shear deformation, but they are gradually destroyed for increasing strain.

Dans cet article on décrit nue série d'essais triaxiaux sur des échantillons qui ont été normale-ment consolidés pendant différentes durées précédant l'essai de cisaillement. On montre que le comportement de l'argile lors du cisaillement dépend de la durée de consolidation de l'échantillon. Avec le temps, l'argile devient plus friable avec des déformations de rupture plus faible et la résistance au cisaillement “non drainée” augmente legèrement. L'étude des courbes déformation-contrainte, mènent à la conclusion suivante: l'effect du temps peut s'expliquer par l'augmentation des lines de cohésion aux points de contact entre les particules. Les liens de cohésion conduisent à une plus grande résistance à la déformation due au cisaillment, mais ils sont progressivement détruit en raison de l'effort croissant.
Plane slope failures in the Langhe region of Italy
Authors: BOTTINO G. , CHIGHINI S. , LANCELLOTTA R. , MUSSO G. , ROMERO E. , VIGNA B.
Published: November 2015

Widespread plane slope failures have occurred in the hilly Langhe region (NW Italy) over the past two centuries and more recently in November 1994. The 1994 event caused the deaths of 20 people and major damage to properties. This paper is a description of the landslides that occurred in connection to flexural slip. The causes of the phenomena are discussed in detail, including the variation of the residual strength along the shear surface as a result of specific geological, chemical and mineralogical conditions. After examining the phenomena that contribute to create slide-prone slopes, the paper concentrates on the driving mechanisms applying to the case histories investigated.
Microscopic numerical model of fluid flow in granular material
Authors: SHIMIZU Y.
Published: November 2015

A microscopic numerical model of fluid flow through granular materials using the discrete-element method is developed to take account of the effect of particle movement. The scheme solves for fluid pressure in void spaces surrounded by the particle elements used in the discrete-element method to consider the compressibility of fluid during particle movement and diffusion, that is flow across void spaces in a one-dimensional form of Darcy's law. The calculated fluid pressure is applied to particles involved in the void space as a body force proportional to the occupied area in the space. This microscopic two-way coupling method enables the analysis of the microscopic mechanical characteristics of granular materials associated with fluid, as many problems in geotechnics involve such interactions between particles and a pore fluid. The approach can be applied in situations with undrained dynamic loading inducing excess pore water pressure and subsequent liquefaction. The paper first describes the formulation and the numerical scheme, then two-dimensional simulations are conducted to validate the scheme.
Modelling the stress–deformation behaviour of municipal solid waste
Authors: KRASE V. , BENTE S. , KOWALSKY U. , DINKLER D.
Published: November 2015

Conceptual modelling of municipal solid waste landfills is vital for prognosis of the long-term development and the assessment of risk potential. Landfills are considered as heterogeneous porous structures, in which flow and transport processes of gases and liquids are combined with local material degradation and mechanical deformation of the solid skeleton. This contribution deals with a constitutive model focusing on the mechanical deformation behaviour of the disposed waste dividing the solid material into two different fractions. The first fraction includes more grainy particles and has properties comparable with granular materials. The second fraction consists of more fibrous constituents having an important influence on the strength of the composite material. Stress–strain behaviour of the two fractions is modelled according to the theory of finite elasto-plasticity. Settlements generated by mechanical creep are also included in the model. The developed constitutive model is validated and calibrated on results from laboratory experiments applying genetic algorithms. Numerical analyses using the finite-element method show the capability of the presented approach.
Use and misuse of the isotache concept with respect to creep hypotheses A and B
Authors: DEGAGO S.A. , GRIMSTAD G. , JOSTAD H.P. , NORDAL S. , OLSSON M.
Published: November 2015

Time-dependent settlements of thick in situ clay layers are normally analysed based on results of thin laboratory specimens. However, the time used to complete primary consolidation is significantly different for laboratory specimens and in situ soil layers. Two totally different cases, referred to as creep hypotheses A and B, have been used as a basis of discussion to assess the effect of creep during the primary consolidation phase. Several laboratory and field experiments have been conducted to study the effect of soil layer thickness on the time-dependent compressibility of a soil layer. Some of these tests seemed to support hypothesis A, others hypothesis B, and in some cases showed a behaviour between the two. As a result this question has continued to be a controversial topic among researchers, and remains to be an issue that needs to be resolved. In this study, some relevant experimental investigations from the literature are thoroughly studied and critically reviewed, and also explained consistently using the isotache concept. This work indicates that the isotache approach can capture the main characteristics of the time-dependent compressibility of clays during both the primary and secondary consolidation phases. It is also shown that the misuse of the isotache concept, as reported in the literature, may give a confusing picture of reality. Based on the considered data, it is demonstrated that the measured time-dependent compressibility of clays agrees well with hypothesis B.
Centrifuge modelling of upheaval buckling in sand
Authors: White D. J. , Barefoot A. J. , Bolton M. D.
Published: November 2015

When operating at high temperature and internal pressure, initial imperfections in a cold laid pipeline can lead, through expansion and an increase in axial stress, to imperfection· growth and upheaval buckling. Efficient design against upheaval buckling requires accurate prediction of soil uplift resistance. However, current design methods are based on empirical uplift factors chosen from soil classification data, and do not capture the strong influence of backfill density on uplift resistance.

A series of tests are reported, in which the pipe uplift is modelled in a 0.8 m diameter mini-drum centrifuge. A key advantage of the mini-drum centrifuge is that uplift tests can be carried out on small soil samples taken from boreholes along the pipeline length. Pipe uplift can be considered as a routine laboratory test.

The results demonstrate the strong influence of backfill density on peak uplift resistance. Observation of the failure mechanism suggests that existing design methods based on vertical slip planes are unrepresentative of the failure. Instead, a new solution is presented, which more closely represents the observed mechanism, and provides excellent correlation with the measured data of peak uplift resistance across a range of backfill densities. Design curves are presented, which require element test results as input parameters. However, upheaval buckling is an unusual example in which centrifuge models, standing alone, provide the most efficient design tool.
Evaluating the coefficient of consolidation using penetration tests
Authors: House A.R. , Oliveira J.R.M.S. , Randolph M.F.
Published: November 2015

This paper discusses the potential for using variable rate penetration tests as a means of assessing the consolidation coefficient for fine-grained soils. Previous testing has shown that the penetration resistance increases as the rate of penetration decreases, owing to partial consolidation in the soil ahead of the advancing probe. This led to the idea of reducing the penetration rate over a short interval during a standard (rapid) test, in order to identify the velocity at which consolidation effects become significant. By matching that point against a normalised backbone curve of penetration resistance versus non-dimensionalised velocity, the consolidation coefficient, cv, of the soil may be deduced.

To explore this idea, a series of penetration tests in kaolin clay were undertaken on a drum centrifuge at the University of Western Australia (UWA), using a cylindrical T-bar penetrometer. A backbone curve was first established using constant penetration rate tests, but with velocities covering nearly 3 orders of magnitude. Then, a series of ‘twitch’ tests were undertaken, where the velocity was successively halved over 8 steps, from a high value (corresponding to undrained conditions) down to 0.4% of the initial value, with the penetrometer being advanced by either 1 or 2 diameters in each step. Comparison of the normalised penetration resistance with the backbone curve provided an estimate of the coefficient of consolidation, which was compared with independent estimates from oedometer tests. The tests gave very encouraging results, with the potential for the value of cv to be estimated within an error band of ±20%.
Measurement of a side-wall boundary effect in soil columns using fibre-optics sensing
Authors: Sentenac P. , Lynch R.J. , Bolton M.D.
Published: November 2015

Side-wall leakage - the preferential flow of water or pollutants near the wall of a soil column - has been studied using in-situ fibre-optical detection of a dye solution at the boundary and in the centre of a soil column. A difference in flow velocity was clearly observed between centre and column wall boundary for different surfaces. The velocity differenceis modified by sand-coating of the wall surface.
Asymmetrical injections near tunnel linings
Authors: Lee S.W. , Bolton M.D. , Mair R.J. , Soga K. , Hagiwara T. , Dasari G.R.
Published: November 2015

Uneven loading resulting from asymmetrical grout injections near a tunnel poses a risk of damaging tunnel linings. Counter-rotation of lining segments at joints concentrates the increase of lining stress and strain at the joints. The damage of lining joints will be more significant if the joints are not constructed properly. This paper discusses results from four centrifuge tests investigating the behaviour of a segmental lining when subjected to nearby asymmetrical injections. The tests were carried out in dense dry sand. Cavity expansion analytical solutions and finite element analysis are also presented to envisage the transfer of the injection pressure to the tunnel and the pattern of the lining deformation. Both analytical and numerical solutions show reasonable agreement with the observed tunnel lining deformation.
Use of the electric analogy for the determination of the shape factor in complex soil conditions
Authors: Lafhaj Z. , Shahrour I.
Published: November 2015

This paper presents a use of the electric analogy for a study of the shape factor, which is used for the determination of the soil permeability from in situ tests. The objective of the study is the determination of the shape factor for complex soil conditions. The paper is composed of three parts. The first one presents the experimental device, while the second one describes the experimental procedure and the methodology used for the interpretation of experimental results. The last part includes a study of the variation of the shape factor with some parameters such as (i) the position of the infiltration cavity with regard to the water table or the substratum, and (ii) the presence of an obstacle or an heterogeneity close to the cavity.
Modelling of DNAPL behavior in vertical fractures
Authors: Levy Laurent C. , Culligan Patricia J. , Germaine John T.
Published: November 2015

This paper describes an investigation into DNAPL behavior in saturated, smooth-walled, vertical fractures. A new theoretical model, which accounts for contact angle dependency on velocity and pinning of the DNAPL-water interface at the walls of the fracture, is developed. Centrifuge scaling laws relevant to the problem are derived through partial inspectional analysis of the model equations. A series of centrifuge tests mimicking DNAPL infiltration into circular fractures of different diameters is described. Comparison of the centrifuge test data with prototype experiments is used to verify the centrifuge scaling relationships. Selected centrifuge test data are also used to validate the new theoretical model. The work demonstrates that the criterion for DNAPL to infiltrate a fracture can be modeled using the geotechnical centrifuge. However, the infiltration kinetics within a fracture are not always properly scaled. The work clearly illustrates the influence of contact angle variability, pinning forces and inertia on the physics of DNAPL behavior in an idealized fracture.
Performance of time domain reflectometers installed on a centrifuge
Authors: Xu Zhenglai , Fujiyasu Yoshimasa , Pierce Charles E.
Published: November 2015

Time domain reflectometry (TDR) offers a diverse monitoring tool for physical soil models, particularly for tracking multiple fault locations along a single embedded sensor. This paper compares the performance of two TDR systems for use in geotechnical centrifuge experiments. The spatial resolution and sensitivity of two different reflectometers (Tektronix 1502C and Campbell Scientific TDR 100) are investigated at 1-g and on a centrifuge up to 50-g. The influence of multiplexers (VAZEC TR 200 and SDMX 50) on signal quality is quantified and discussed. Six different coaxial cable sensors are evaluated in the centrifuge, including four prototype sensors that are being created and tested for their capacity to detect shear zones in soils. According to experiments conducted at 1-g and in a centrifuge, the Tektronix system consistently provides a higher spatial resolution and sensitivity. Multiplexing sensors at any gravitational level, however, increases the signal rise-time such that spatial resolution and sensitivity are reduced. With proper set-up, both TDR systems can be securely employed in centrifuge tests, and relatively low centrifugal forces do not affect their operation. Voltage signals acquired at high g-levels are identical to those acquired at 1-g for five of the six cable sensors.
Ten years centrifuge operation at a consulting firm
Authors: Terashi Masaaki , Katagiri Masaaki , Ohishi Kanta
Published: November 2015

Thirty-seven geotechnical centrifuges are available in Japan and around ten centrifuges are owned and operated by the research institutes of the private industries in Japan. These centrifuges constantly produce research results that appear in the domestic and international conferences and symposia. The subject of these research papers ranges from the basic scientific issues to practical issues. Such active research works in the private sector look quite unique or strange for those outside Japan. The present article is aimed to show in what situation and how the privately owned centrifuges in Japan are utilized by raising three pieces of research works conducted at a consulting firm.
Statnamic testing of model piles in a clay calibration chamber
Authors: Brown Michael , Anderson William , Hyde Adrian
Published: November 2015

The rate of load application during a Statnamic pile test lies between that for static and dynamic pile tests. Current analysis methods offer excellent correlation between Statnamic and static test results for coarse-grained soils. However, over-prediction of pile load capacity can be obtained for fine-grained soils. It is very difficult to explore this anomaly using full scale field tests because of natural soil variability, so a study has been carried out using a model pile installed in similar clay beds prepared in a large triaxial calibration chamber. The instrumented model pile has been loaded at varying rates by a computer controlled servo-hydraulic actuator. The tests have simulated static loading, constant rate of penetration at various rates of penetration, and Statnamic loading. Results suggest that components of the rate effect associated with increased pile penetration rates may be described by a power law relationship.
An investigation of the failure mechanism of a cantilever retaining wall under earthquake loading
Authors: Marketos G. , Madabhushi S. P. G.
Published: November 2015

The seismic behaviour of retaining walls is of continuing interest to geotechnical engineers as many of these structures were found to fail following recent earthquakes. In this study an investigation of the development of the failure of a cantilever retaining wall subjected to dynamic loading in dry sand was performed. The small-scale plane strain models produced for this purpose were tested using a new shaking table facility at Cambridge University. Images of the cross-section of the model for each one of these events were recorded by means of a high-speed and high-resolution image-capturing device, which allowed for the complete information on the displacement field to be recorded. The principles of Particle Image Velocimetry, as applied by the GeoPIV software package developed at Cambridge, were then used to process this data by removing the base displacement of the model and calibrating the images from pixel to real space. In this way it was possible to produce displacement and strain plots for any time interval, allowing for the real-time development of the failure mechanism for such a structure to be investigated for the first time. In particular, it was possible to isolate time intervals as small as 10 ms and hence obtain a visualisation of a nearly instantaneous failure mechanism for the structure.
Investigations of a european network of geotechnical centrifuges on multiphase flow
Authors: Oung O. , Bezuijen A. , Weststrate F. , Haza E. , Favraud C. , Garnier J. , Spiessl S. , Taylor N. , Coumoulos H. , Soga K. , Esposito G. , Allersma H.
Published: November 2015

It is necessary to understand how Non-Aqueous Phase Liquids (NAPLs) migrate in the subsurface to evaluate the environmental impact of any accidental release. With this objective, five different geotechnical institutes worked together in an interactive experimental research project on two-phase flow in granular material, within the framework of the NECER programme. The main aim of the programme was to investigate the potential for using a geotechnical centrifuge in this type of research. One-dimensional and two-dimensional experiments were performed. Findings from the programme have shown that centrifuge modelling can be a useful tool in such research. It was demonstrated that less time and smaller soil samples are needed in comparison with 1g experiments and it is possible to simulate conditions at larger depth.
Centrifuge modelling of long-term load acting on a tunnel fixed in space in soft clay
Authors: Ariizumi Takeru , Igarashi Hiromasa , Kaneko Shunsuke , Nagatani Hideki , Yamazaki Takeshi , Kusakabe Osamu
Published: November 2015

A series of centrifugal model tests was conducted to examine the long-term loads acting on a tunnel fixed in space in soft clay, experiencing long-term deformation. Two possible hydraulic boundary conditions were adopted in the experiments: ‘tunnel drainage condition’ where the tunnel lining acts as a drainage boundary, and ‘bottom drainage condition’ in which one-dimensional consolidation of the clay takes place due to lowering of the ground water level. The test results are compared in view of the mechanism of ground deformation around the tunnel and the variation of earth pressures on tunnel lining.
Application of a geocentrifuge and sterolithographically fabricated apertures to investigations of multiphase flow in complex fracture apertures
Authors: Stedtfeld Robert D. , McCreery Glenn E. , Stadler Alan T. , Stoner Daphne L. , Meakin Paul
Published: November 2015

A geotechnical centrifuge was used to investigate unsaturated multiphase fluid flow in synthetic fracture apertures under a variety of flow conditions. The geocentrifuge subjected the fluids to centrifugal forces allowing the Bond number to be systematically changed without adjusting the fracture aperture or the fluids. The fracture models were based on the concept that surfaces generated by the fracture of brittle geomaterials have a self-affine fractal geometry. The synthetic fracture surfaces were fabricated from a transparent epoxy photopolymer using sterolithography, and fluid flow through the transparent fracture models was monitored by an optical image acquisition system. Aperture widths were chosen to be representative of the wide range of geological fractures in the vesicular basalt that lies beneath the Idaho National Laboratory (INL). Transitions between different flow regimes were observed as the acceleration was changed under constant flow conditions. The experiments showed the transition between straight and meandering rivulets in smooth walled apertures (aperture width= 0.508 mm), the dependence of the rivulet width on acceleration in rough walled fracture apertures (average aperture width = 0.25 mm), unstable meandering flow in rough walled apertures at high acceleration (20 g) and the narrowing of the wetted region with increasing acceleration during the penetration of water into an aperture filled with wetted particles (0.875 mm diameter glass spheres).
An electromagnetic horizontal impact device for centrifuge testing
Authors: Hajialilue-Bonab Masoud , Chazelas Jean-Louis , Claude Favraud , Cottineau Louis-Marie
Published: November 2015

The device presented herein consists of an electromagnetic horizontal impact device. The use of a steel ball serves to avoid friction of the impact mass within the guide tube, and the presence of a slight back-slope easily leads the ball back to its initial position after bouncing on the target structure. Repeated impacts can then be triggered and tuned while in-flight. The obtained impact force duration is shorter than the impact of a truck on bridge piles; however, the required level of momentum transmitted to the pile could be attained, as could the other requirements such as remote control, reproducibility and tunability. This device produces sharp impacts that enable modeling the free vibration response of structures or the impulse response in modal terms. Two applications are presented here in order to demonstrate both the versatility of the device and the types of observations it yields: a study of the inertial pile response; and a study of structure-soil-structure interactions, as part of an effort to describe the “site-city interaction”.
Centrifuge tests of shallow footing behaviour on sand under combined vertical-torsional loading
Authors: Bienen B. , Gaudin C. , Cassidy M.J.
Published: November 2015

Extensive laboratory model tests at earth’s gravity (1g) have been performed during the last two decades to investigate the behaviour of shallow foundations under combined loading. These results have been extremely useful to understand the mechanisms taking place and to design a framework to predict the response of foundations under such loading conditions. The potential scale effects associated with the 1g conditions and the extrapolation of the small model results to large prototype foundations, particularly for testing in sand, however, have only been partially investigated. This paper describes a series of lg tests and centrifuge tests performed on shallow circular foundations on sand subjected to combined vertical and torsional loading. The results are discussed within the framework of displacement-hardening elastic-plastic macroelement modelling, with emphasis on the difference between the lg results and the centrifuge results and its consequences for the performance of the framework.
Improvement of the stability of a vertical geotextile reinforced earth wall backfilled with low strength clayey soil
Authors: Chen Huei-Tsyr , Hung Wen-Yi , Chen Po-Wen , Lee Chung-Jung
Published: November 2015

Despite many past studies of clayey geosynthetic reinforced earth walls (GREWs) conducted using geotechnical centrifuge modeling, none have examined the adverse effects of low strength clayey backfill with a high water content resulting from consecutive days of heavy rainfall and poor drainage on the stability of a clayey GREW. In this study a series of centrifugal model tests for vertical geosynthetic reinforced earth walls (VGREWs) was performed to investigate the effectiveness of reducing the reinforcement spacing on the stability of low strength clayey VGREW. The reinforcement spacing for the clayey VGREW was 0.25 m or less with the reinforcement length being 0.71 times the wall height H. The testing to ensure stability under the worst weather conditions was done in the Linkou area. It was found that for a low strength clayey VGREW, the pattern of deformation of its wall face depends upon the reinforcement spacing.
The interaction of reverse faults with flexible continuous pipelines
Authors: Bransby M.F. , El Nahas  , Turner E. , Davies M.C.R.
Published: November 2015

Permanent ground displacements due to earthquake faulting may induce large deformation and loading of a buried pipeline. In particular, a pipeline crossing a fault rupture emerging at the soil surface will be subject to a combination of bending and/or axial compression or tension depending on the form of the fault displacement, the dip angle and the direction of the pipe with respect to the fault. This complex combination of loadings may be sufficient to cause disruption to the pipeline supply or leakage of product and so has potential for large financial and/or environmental impact. In this paper, the response of buried flexible pipelines crossing reverse fault ruptures has been examined using centrifuge modelling. A reverse fault is actuated in the 20th-scale model at an initial fixed dip angle in the bedrock and the fault rupture is seen to propagate upwards through a layer of sand towards the soil surface. Pipelines were buried in the sand layer to typical embedment ratios and their response was monitored as the fault displacement increased monotonically. Primary data capture was by the use of image analysis: semi-cylindrical modelm pipelines were placed at the front-face of the model and digital images were captured during the loading event. This allowed pipeline deformation patterns and thereby bending moment distributions to be calculated throughout the fault rupture event. Results are presented to show the effect of pipeline diameter, stiffness and embedment depth on the performance of buried pipelines during reverse and normal faults. In particular, it is shown that additional embedment of the pipeline is detrimental to its performance due to the additional confining effect of the soil which changes the relative pipe­soil stiffness.
Modelling of double porosity clays in a mini-centrifuge
Authors: Najser J. , Pooley E. , Springman S.M.
Published: November 2015

Physical modelling of double porosity clay was carried out in a mini-centrifuge. These tests were performed as a preliminary study for modelling a case history from Northern Bohemia in the large geotechnical drum centrifuge. The main aim of these tests was to investigate the effect of lump size distribution on soil compressibility during self-weight consolidation. In addition, oedometer tests were carried out to investigate the response of double porosity soil to one dimensional loading with the attendant degradation in structure. Comparison with large centrifuge test results showed good correlation, despite the simple test procedure.
A comparative study between dynamic shake table test and shear box test in a centrifuge
Authors: Shibayama S. , Izawa J. , Takahashi A. , Yamada T. , Nagatani H. , Ohbo N. , Kusakabe O.
Published: November 2015

A comparative study of centrifuge dynamic shake table test and centrifuge pseudo-static shear box test was conducted on the same prototype model to experimentally examine applicability of the seismic displacement method which is adopted in seismic design for underground structures in Japan. The model used was a rectangular shape tunnel embedded in dry sand. The detailed strain measurements were made on the model tunnels as well as relative displacement between upper and lower slabs of the tunnel for direct comparison between the results obtained from the two different test types. The study confirmed that the centrifuge pseudo-static shear box test provides valuable information on structural responses which are very much similar to those observed in the centrifuge shake table test.
Spudcan deep penetration in multi-layered fine-grained soils
Authors: Hossain Muhammad Shazzad , Randolph Mark F. , Saunier Yvette N.
Published: November 2015

This paper reports centrifuge modelling of spudcan foundations penetrating through multi-layered clays with interbedded stiff layers. Test specimens were prepared covering a range of normalised layer soil properties and geometry, mostly mimicking strength profiles from reported case histories, particularly those where punch-through failure occurred. Punch-through and rapid leg penetration (for strong-over-weak) and squeezing (for the reverse) were demonstrated by the penetration resistance profiles and associated soil failure mechanisms and provide a basis for developing design calculations. The results were compared directly with a field record of spudcan load–penetration response to evaluate their accuracy in predicting the shape of the spudcan resistance profile and final penetration depths, with excellent agreement obtained. A limiting squeezing depth of about 0·15D was observed, increasing marginally with strength ratio, sul/suu, but with much greater depths where a soil plug was carried down from an upper strong layer with the spudcan. Where a stiff layer was underlain by a weaker layer, punch-through occurred with increasing severity for relatively lower strength ratio, sul/suu, and higher stronger layer thickness ratio, t/D. The severity of punch-through behaviour was reduced by the squeezing influence of another stiff layer within a short distance (less than about 0·6D).
Deterioration mechanism of Portland cement paste subjected to sodium sulfate attack
Authors: Liu Kaiwei , Deng Min , Mo Liwu , Tang Jinhui
Published: November 2015

External sulfate attacks on cement-based materials may cause deterioration in terms of cracking, softening and spalling. This work aimed to investigate the damage process and deterioration mechanism of Portland cement pastes exposed to sodium sulfate attack. Cement pastes were immersed in 0·031 mol/l (0·44 wt%) and 0·352 mol/l (5 wt%) sodium sulfate solutions at 20°C for up to 900 d. The surface appearance, mass change and compressive strengths of the cement pastes were investigated during the sulfate attack process. Mineral phases formed in the surface layer and the inner portion of the cement pastes were investigated with X-ray diffraction at different stages of deterioration. Scanning electron microscopy was used to further examine cement paste microstructures after immersion in 0·352 mol/l sodium sulfate solutions for 180, 300, 600 and 900 d. The results showed that the deterioration in cement pastes first occurred in the surface area and then gradually extended to the inner portions. Ettringite was the main product at the initial attack stage, while gypsum was formed at later stages. The formation of fine ettringite resulted in volume expansion of the cement pastes. Gypsum was formed as veins that were sub-parallel to the surface. Ultimately, gypsum formation was accompanied by the decalcification of calcium silicate hydrate, causing softening of the external cement paste layer.
Cement production by cement-bonded wood particleboard wastes
Authors: Yilmaz Mustafa , Tokyay Mustafa , Yaman Ismail Ozgur
Published: November 2015

To improve the sustainability of cement and concrete production, there is an increasing trend towards using industrial wastes throughout their production processes. The aim is to find new resources that can be used in any step of cement and concrete production and to find solutions to many problems related to the disposal of wastes. This article discusses the use of wastes generated from cement-bonded wood particle board (CB) manufacturing in cement production. CB waste, which basically contains wood chips and hydrated cement, cannot be recycled within the CB process itself; it thus has to be disposed of and does not have any economic value. However, CB waste can be burned in cement rotary kilns, which may result in certain energy savings due to the presence of wood particles as a secondary fuel. Furthermore, the hydrated cement may decompose and clinker compounds may reform during a calcination process. This work investigated the possibility of using CB waste in cement manufacturing and its effects on energy consumption and cement characteristics. The results indicate that CB waste can be successfully used to partially replace the raw mix in cement plants.
A method for the reduction of deformation of high-strength lightweight cement concrete
Authors: Inozemtcev Aleksandr Sergeevich , Korolev Evgenij Valerjevich
Published: November 2015

This paper presents research into the deformation properties of high-strength lightweight concrete (HSLC) containing hollow aluminosilicate microspheres. A method of increasing the fracture toughness of the HSLC by using a modifier as a coupling agent on the surface of the microparticles of aggregate is proposed. Use of the hollow microspheres is proposed to produce lightweight concrete with high performance characteristics: increasing the content of spherical microparticles in the concrete composition promotes the formation of a close-packed structure with low deformation. The coefficient of fracture toughness of the HSLC was found to be comparable to that of fine-grained high-strength normal concrete and is limited by the strength characteristics of the micrometric aggregate particles. The aim was to create an active iron–silica shell on the surface of the hollow spheres, which interacts with the major components and products of cement hydration and reinforces the phase boundary. The proposed method reduced longitudinal and transverse deformations of the HSLC by 1·20–1·60 and 1·37–2·21 times respectively. The elastic modulus of the HSLC was determined to be 6·0–8·5 GPa, with a Poisson's ratio of 0·08–0·14. The nanomodifier reduced the intensity of cracking under the influence of shrinkage stresses of HSLC by 56·9%.
Effect of biotechnologically modified alginates on LDH structures
Authors: de Reese Johanna , Sperl Nadine , Schmid Jochen , Sieber Volker , Plank Johann
Published: November 2015

Four alginates possessing different guluronic/mannuronic acid ratios and one acetylated alginate were investigated with respect to their behaviour during intercalation into layered double hydroxides (LDHs). Two alginates were commercial products while the others were synthesised by way of bacterial fermentation and in one sample followed by enzymatic treatment. Intercalation was performed by way of co-precipitation of aluminium nitrate and zinc nitrate in alginate solution at a pH of 8·5–9. The products were characterised by powder X-ray diffraction, elemental analysis, wide-angle X-ray scattering, scanning electron microscopy and magic angle spinning (MAS) NMR spectroscopy. All alginates intercalate well into the Zn2Al-LDH host structure. With an increase in the content of guluronic acid in the alginate, the d-spacing (interlayer distance) in the alginate-LDH compound increases from 1·28 to 1·85 nm. Similarly, acetylation of the carboxylic groups leads to an increased steric volume of such alginate and therefore to a higher d-spacing (1·72 nm). The results indicate that different guluronic/mannuronic acid ratios can be used to trigger the steric size of the alginates and consequently the d-spacing of the alginate-LDHs. 13C CP MAS NMR spectroscopy confirmed an interaction between the carboxylic groups present in the alginate with the inorganic main layer.
Dynamic mechanical analysis of fish dermal armour from A. gigas and P. pardalis
Authors: Torres Fernando G. , De la Torre Daniel , Merino Monica
Published: November 2015

Fish scales and fish dermal plates are collagen-based structures with interesting mechanical properties especially as model materials for bioinspired nanocomposites. This paper reports the dynamic mechanical behaviour of two types of fish body armour structures: fish scales from Arapaima gigas and dermal plates from Pterygoplichthys pardalis. Both structures were tested using a dynamic mechanical analyzer (DMA) to determine their storage modulus and their loss factor as a function of temperature. DMA provides information on the damping properties and energy dissipation characteristics of these types of dermal armours. Although both materials are made out of collagen reinforced with hydroxyapatite, fish scales display a laminated structure, while dermal plates show a sandwich-like porous structure. Arapaima gigas scales showed a transition at around 0–10 °C, while P. pardalis dermal plates displayed behaviour similar to bone with no definitive thermal transitions. Fish scales showed a higher capacity for energy dissipation during deformation, quantified by a higher value of the loss factor, compared to dermal plates and likely due to their fibre reinforced laminated structure.
Introducing biomimetic approaches to materials development and product design for engineering students
Authors: Cleymand Franck , Rousseau Marthe , Mano João F.
Published: November 2015

In this paper, we present a new course entitled “Biomimicry: from life to nanotechnological innovations” at the Mines Nancy Engineering School, Nancy, France, and explain how we developed a specific curriculum covering biomimicry. We discuss strategies that can be followed by teachers to explain selected contents in the multi-disciplinary field of biomimicry and/or bioinspiration to undergraduate students and how practical classroom activities can be conducted as individual or team work. We hope that sharing our experience will help teachers and senior researchers disseminate useful concepts and real examples of biomimetic principles and tools for the development of new materials, new/improved design and fabrication strategies, and innovation methodologies.
Planning and implementing coastal management in Sri Lanka
Authors: Hettiarachchi Sam S. L. , Samarawichrama S. P.
Published: November 2015

Sri Lanka is one of the island states to have developed very early, and operated fully, a coastal management plan on a national scale. The Coast Conservation Department, by Act of Parliament, has full responsibility for the implementation of the plan. The plan is periodically revised to incorporate emerging challenges, current and projected development trends, in refining policies and guidelines. The paper presents a review of planning and implementation of the coastal zone management in Sri Lanka. It focuses on the approach to coastal zone management via regulation of development activities and environmental protection, second-generation and current initiatives, challenges and constraints. The paper concludes with the future outlook, focusing on the role of the Coast Conservation Department and the relevance of the use of integrated coastal zone management frameworks.
Understanding novel structures through form-finding
Authors: Lewis Wanda
Published: November 2015

Society expects civil engineers to continue to produce exciting and innovative structures, particularly for landmark buildings and bridges. However, recent high-profile failures call for a review of commonly used design methodologies. Current engineering design practice tends to replace knowledge of mechanics by codes of practice and physical modelling by computer-based calculations. This paper suggests that ‘form-finding’, a combined physical and mathematical modelling technique used to develop tension and shell structures, should also be applied where innovative designs are envisaged.
Marine energy: getting power from tides and waves
Authors: Kerr David
Published: November 2015

Marine renewable energy has the potential to make a significant contribution to energy supplies in the future. Tidal barrages and wave energy could make the largest contribution, both in the UK and elsewhere, and tidal streams could make a smaller but still useful contribution. This paper provides an overview of the current status and prospects for electrical generation from marine energy. It concludes that a realistic target contribution to UK electricity supplies would be about 75 TWh. However, although tidal power is predictable, all forms of marine energy are variable and intermittent and integration into the electrical grid is a critical issue if they are to achieve their potential contribution.
A risk-based decision-support system for bridge management
Authors: Flaig Katja D. , Lark Robert J.
Published: November 2015

Based on a study of those actively involved in bridge management this paper presents a novel framework for an advanced bridge management system. The framework has a modular format and includes components for dealing with inspection, data collection and storage, deterioration modelling, structural assessment, economic appraisal of maintenance, repair and rehabilitation (MR&R) actions through whole-life costing, work programme optimisation methodologies and a number of reporting facilities. Of primary importance to the bridge management process is the assessment of structural adequacy. If assessments are unduly conservative, structures will be unnecessarily restricted or strengthened, whereas if the rules are lax, some structures may be left in service without having an appropriate margin of safety against failure. To address this issue a procedure for a reliability-based assessment approach is presented and it is shown how such an approach, when part of the above system, can provide bridge managers with an innovative, rational, risk-based, decision-support tool.