bluuebunny/crossref_metadata_2025 huggingface dataset:
Safety and cost-effectiveness of clear zones in Iran
Authors: Ayati Esmaeel , Shahidian Mahdi
Published: November 2015

This paper examines different clear-zone improvement alternatives in rock cuts, and compares the likely effect on safety and construction costs. Where a roadway passes through rock cuts, the construction cost of providing the clear zone is very high. This paper is based on research that demonstrates a method for selecting the appropriate clear zone in rural two-lane highways in Iran based on the site and traffic conditions expected at the site. A method is described for determining the rock-cut width that best balances the cost of construction with the improvements in safety that would result from a wider clear zone in the rock cut. The objective of this study is to quantify the societal cost of rock-face accidents, so that the costs and benefits associated with different clear-zone policies can be explicitly addressed during the preliminary design process. This study shows that the need for extra clear-zone width in steep and bendy routes (specially with external curves of less than 195 m radius) is more critical than that for straight and level ones. The existence of external horizontal curves simultaneously with severe longitudinal slopes increases the probability of vehicles’ encroachment by as much as eight times in comparison with straight and level routes. An interesting point to note is that, by providing wider lanes, the need for extra clear-zone width is reduced dramatically.
Briefing: Making tomorrow a better place
Authors: Leiper Quentin
Published: November 2015

This is an extract on the subject of ‘sustainability’ from the inaugural address by Quentin Leiper, who became 142nd president of the Institution of Civil Engineers on 7 November 2006.
Intelligent travel: planning for the revolution
Authors: Stewart Will
Published: November 2015

This paper describes the 50-year view by the UK Government’s Foresight programme of the future of intelligent transport infrastructure, its implications and its social context. By 2055, it is envisaged that intelligence and pervasive information will be built in to everyday life, encompassing needs to communicate and travel. People will better understand the resource implications as well as the direct costs of their lifestyles—and perhaps they will actually travel less. However, given the slow speed at which infrastructure systems adapt, the research concluded that civil engineers need to start planning now for the inevitable travel revolution. The paper is based on the author’s 2006 Unwin lecture, delivered to the Institution of Civil Engineers and Institution of Mechanical Engineers on 6 April 2006, prepared with Phil Blythe of Newcastle University.
Risk management and value management in project appraisal
Authors: Doni Afila , Smith Nigel J.
Published: November 2015

The appraisal phase of the project life cycle commences with the inception of the project and ends with the sanction of the project for implementation. During the appraisal phase the key decisions on the viability of the project and the most feasible project option are made in sequence. To enable good ideas and realistic projects to be recognised, both risk management and value management techniques are used, among others. This paper examines current industrial practice in project appraisal and indicates why some practitioners expressed a preference for one of these techniques and some for the other. Those preferring value management prior to risk management stated that the objectives of the project and the definition of options must be examined first, whereas those implementing risk management first considered that assessing the risks of the plan developed to achieve project objectives must take priority over maximising opportunities. Both techniques are important in decision making under uncertainty during project appraisal but greater knowledge of their application will reduce future costs incurred through failure to correctly identify viable projects at an early stage.
Design and construction of Bukit Panjang LRT, Singapore
Authors: Leung Yew Wah , Button Jon S. , Yap Andrew Y. Y. , Ng Kee Nam
Published: November 2015

The Bukit Panjang light rapid transit (LRT) system, a groundbreaking project for the Land Transport Authority of Singapore, was designed to serve as a feeder to the existing mass rapid transit network and the Bukit Panjang bus interchange. The main civil engineering elements consist of 7·8 km of twin-track elevated guideway, 14 stations and a maintenance depot with an operation control centre. The system was completed and opened to the public in November 1999. This paper discusses the design and construction of the LRT guideway, which consists mainly of precast prestressed concrete segmental box girder bridges with epoxy glued joints and internally prestressed tendons. The bridge decks are predominantly simply supported spans ranging from15 to 34 m; however, a few special decks are made continuous due to stability requirements. Two overhead launching girders were employed for erecting the guideway. Due to specific site constraints and system requirements, the alignment was characterised by numerous tight curves with a minimum horizontal radius of 60 m. The geometry control method and construction equipment, such as the casting cells and the launching girders, were tailor-made in order to tackle the unconventional situation. Some operation and maintenance aspects of the system are also covered in this paper.
Developments in geotechnical best practices in evaluating embankment dams
Authors: Eddleston Malcolm , Scholefield Ian
Published: November 2015

This paper describes the development of some geotechnical approaches to the assessment of embankment dams since the introduction of the Reservoirs Act in 1975. The initial developments took place in response to a number of industry-led initiatives instigated with UK government support leading up to and following the implementation of the Act. The approaches primarily relate to seismic and slope stability and internal erosion risks. A timeline mapping the evolution of approaches and best practices is presented.
Compactness of coatings treated by MAO and LSM on Ti alloy
Authors: Wang Fengbiao , Hou Bo , Yuan Kai , Wang Yongqing
Published: November 2015

Microarc oxidation (MAO) coatings exhibit loose surfaces, big micropores and porosity that lead to shortcomings in mechanical properties. Three kinds of MAO coatings were prepared on TC4 alloys (Ti–6Al–4V) in electrolyte and treated by laser surface melting (LSM) with various power densities. Compactness of the coatings was analyzed based on the scanning electron microscope images. The results showed that the porosity and the average diameter of pores were decreased, and a compact remelting layer was formed in the MAO+LSM coatings. On the discontinuous smelting surface of MAO+LSM coating, pores were often found in the individual melting microarea. Most of molten pools were originated in the pore of MAO coating surface; as the laser energy was absorbed continually, discrete melted areas grew and finally expanded into continuous melted areas. The content of anatase increased after LSM treatment especially under low scanning speed of the laser beam. The average hardness of MAO+LSM coatings is almost twice the hardness of MAO coating, and the wear resistance is also excellent for compactness of LSM coating. Consequently, to improve the coating mechanical properties of TC4 treated by MAO, the secondary modification process of laser remelting plays a positive role.
Fly ash/paper sludge as constituents of cements: hydration phases
Authors: García Giménez Rosario , Vigil de la Villa Raquel , Goñi Sara , Frías Moisés
Published: November 2015

Ternary cements prepared with equal amounts of thermally activated paper sludge and fly ash in proportions of 35% and 50%, in substitution of ordinary Portland cement, are mixed to study their phase stability. The underlying intention is to increase the proportional substitution of waste products in these types of cement, thereby consigning less waste to landfill sites. The hydration phases of the cement specimens were analysed using thermogravimetric/derivative thermogravimetric (TG/DTG) analysis, X-ray diffraction, scanning electron microscopy/energy-dispersive X-ray (SEM/EDX) spectroscopy. The phases identified in the cement blends include Portlandite, monocarboaluminate compound C4AC̅H12, and layered double hydroxides–type compounds (LDH), as well as ettringite and calcium silicate hydrate gels. Increased formation of both tetracalcium aluminate carbonate 12 hydrate (C4ACH12) and LDH-type compounds and reductions in ettringite and portlandite were observed when the proportional substitution of cement by waste products rose from 35% to 50%. A characteristic compound of pozzolanic reactions, bicalcium silicate (C2ASH8), was not observed, suggesting that it is inhibited in these types of substitutions.
Evaluation of a four-component composite landfill liner system
Authors: Stark Timothy D.
Published: November 2015

The performance of four different municipal solid waste landfill liner systems common in the United States, that is, USEPA Subtitle D prescribed composite liner system, composite liner system consisting of a geomembrane (GM) overlying a geosynthetic clay liner (GCL), Wisconsin NR500 liner system, and a proposed four-component composite liner system that is a combination of the GCL composite liner and Subtitle D liner system (with a 61-cm or 91·5-cm thick low hydraulic conductivity compacted soil), were evaluated in terms of leakage rate, solute mass flux, and cumulative solute mass transport. Leakage rates through circular and non-circular GM defects were analysed using both analytical and numerical methods. For the mass flux evaluation, solute transport analyses using GM defects and diffusion of volatile organic compounds through intact liners were conducted using one- and three-dimensional numerical models. Cadmium and toluene were used as typical inorganic and organic substances, respectively, in the analyses. The comparison shows that for the limited set of conditions considered, the four-component composite liner system outperforms the Subtitle D and Wisconsin NR500 liner systems based on leakage rate and mass flux and provides similar results to the GM/GCL liner system. Based on the analyses presented herein the four-component liner system is a viable choice for a protective Subtitle D composite liner system and provides some added protection to the GCL.
Passive cooling of roof over composite climate in India
Authors: Sakhare Vishakha V. , Ralegaonkar Rahul V.
Published: November 2015

Heat gain in buildings is a major problem in most climatic zones in India, especially in the study area of Nagpur in Maharashtra. It is particularly acute in the top storeys of buildings directly beneath the roof, where internal temperatures generally exceed the ambient temperature. To reduce the heat gain of roof surfaces a combination of sustainable reflecting and insulating materials – comprising broken glazed tiles laid on the roof surface and false ceiling tiles made of mineral fibre board, including sawdust and expanded polystyrene – is proposed. The materials are retrofitted over and under the existing concrete roof of a room in an educational building, which is then monitored for a year. The retrofitted materials are found to be light in weight (26 kg/m2), low in cost (£12/m2) and result in a 3·9 times increase in thermal resistance. The retrofitted roof provides an average 5·9°C reduction in temperature and keeps room temperatures under 27°C for 34% of the year.
Benchmarking energy performance in commercial buildings
Authors: Clark David
Published: November 2015

The main purpose of energy benchmarking in commercial buildings is to put actual energy consumption into perspective so that building owners and occupiers can take steps to reduce it. Many rating tools, such as the display energy certificate in the UK, are primarily based on floor area. This means that nearly empty buildings can receive a good rating while intensively utilised buildings are penalised, even though their energy use per person may be much lower. To provide more meaningful benchmarking requires consideration of the intensity of use. This paper proposes a simple approach to include occupancy density and hours of use in the benchmarking methodology for commercial buildings. The paper also discusses how landlord and tenant energy can be benchmarked separately to reflect who is responsible for the energy consumption. Finally, the paper suggests modifying the standard A to G rating scale used in the UK to better reflect the diversity of energy performance in commercial buildings.
Organising urban symbiosis projects
Authors: Vernay Anne Lorène , Mulder Karel F.
Published: November 2015

Urban symbiosis is a strategy to create a more efficient metabolism of cities. However, urban symbiosis requires the integration of different systems, which is hard to achieve. Actors involved in existing systems can hardly develop ‘the bridges’ that are required to connect the thus far unrelated worlds of pre-existing systems. This paper analyses two cases of urban symbiosis and focusses on the process of building new actor networks. Urban symbiosis projects are generally complex and involve various stakeholders. The authors conclude that the introduction of additional actors or an additional institutional framework might be an effective means to create bridges between actors that could facilitate a more efficient metabolism of cities.
Loss of value: effects of delay on hydropower stakeholders
Authors: Plummer Braeckman Judith , Guthrie Peter
Published: November 2015

Preconstruction delays (in some countries referred to as planning delays) are traditionally considered less damaging than delays that occur during construction. It transpires from this analysis that, for many project stakeholders of a hydropower project, delay before construction starts is just as damaging as time lost during construction, sometimes more so. In particular, preconstruction delay could adversely affect the government, the local people affected by the project, the environment and the project beneficiaries (e.g. consumers of power or water or those benefiting from flood protection). The project developer is adversely affected by preconstruction delay, but generally not to the same extent as by construction delay, and may thus appear to be more focused on minimising construction cost and time overruns. This research is set in a developing country context, where the economic stakes are higher and the effect of delay may be more obvious than in developed economies.
Consolidation analysis of soft soil improved with short deep mixed columns and long prefabricated vertical drains (PVDs)
Authors: Zhang Z. , Ye G. , Xing H.
Published: November 2015

ABSTRACT: Soft soils may pose many challenges to construction of roadway embankments, such as low bearing capacity, excessive settlement, and slope instability. A combined method involving the use of deep mixed (DM) columns and prefabricated vertical drains (PVDs) was proposed to reinforce the soft soils. In the application of the combined method, the DM column is usually shorter than the PVD. To obtain an analytical solution of the composite foundation with short DM columns and long PVDs, the drainage system was converted into a cylindrical drain wall with equivalent properties, and only the radial drainage was considered. An axi-symmetric unit cell was established and the solution of average degree of consolidation was derived. The analytical solution was verified by comparisons with the results computed by three-dimensional finite element analyses. A parametric study was conducted to investigate the influence of diameter of DM column, moduli of DM column and soft soil, permeability of DM column, soft soil and smear zone, and improvement depth of DM column on the soil consolidation and some recommendations were proposed for its practical application. Based on the proposed solution a design chart was developed which can be used to easily obtain the degree of consolidation for soft soil improved by the combined method. The proposed design method was applied to a case history of an embankment on soft soil with short DM columns and long PVDs. Good agreement was found between the predicted average degree of consolidation and the field data.
Obtaining reliable embodied carbon values for geosynthetics
Authors: Raja J. , Dixon N. , Fowmes G. , Frost M. , Assinder P.
Published: November 2015

ABSTRACT: Changing climate and the damaging effects of carbon dioxide (CO2) on the environment, has led to awareness throughout the construction industry of the need to deliver more sustainable solutions. Robust and rigorous carbon footprinting procedures for assessing solutions and projects can help to identify where action can be taken to reduce CO2 emissions. It also promotes the marketing of those solutions and methods that produce lower CO2 emissions. Geosynthetics often provide a cost-efficient alternative to more ‘traditional’ construction techniques. Recently, work by the Waste and Resources Action Programme in the UK has shown that geosynthetic solutions can also produce much lower CO2 emissions. However, there are still questions as to the reliability of such calculations. Although the methodologies employed are relatively consistent worldwide, the accuracy of the embodied carbon data available for use in calculations remains uncertain. Geosynthetic products are not specifically included in the embodied carbon construction materials databases most commonly employed in Europe, and often generic values for polypropylene and polyethylene are used. This paper presents a study in which the embodied carbon data for geosynthetic products was calculated using first-hand manufacturing process data. The values calculated for two categories of geosynthetics were considerably lower than commonly employed database values. Nonwoven geotextiles had an average embodied carbon value of 2.35 tCO2e/t, with values for example geogrids of 2.97 tCO2e/t for extruded and 2.36 tCO2e/t woven.
Numerical studies on the performance of hybrid-geosynthetic-reinforced soil slopes subjected to rainfall
Authors: Bhattacherjee D. , Viswanadham B. V. S.
Published: November 2015

Slope instability due to rainwater infiltration poses a serious problem, and causes thousands of deaths and severe damage to infrastructures each year. In the present study, the effect of inclusion of hybrid-geosynthetic layers within a slope subjected to rainfall was investigated numerically. The analysis was done with and without hybrid-geosynthetic layers embedded in a silty sand slope having 2V:1H inclination with rainfall intensities ranging from 2 mm/h to 80 mm/h. The rainfall was simulated numerically for 24 h, and seepage, deformation and stability analyses were performed at the onset of rainfall, during rainfall, and up to 24 h after rainfall. Further, the need for both drainage and reinforcement function in the reinforced slope was highlighted by analysing the effect of geotextile and geogrid layer inclusions separately on the slope subjected to rainfall. The results indicate that, the inclusion of hybrid-geosynthetic layers was effective, as it lowered the phreatic surface by causing a reduction in excess pore water pressure. Further, the static global stability of a hybrid-geosynthetic-reinforced slope was found to increase considerably under all intensities of rainfall, while the deformation values were significantly lower for the reinforced slope as compared with that of the unreinforced slope.
Full-scale load test and finite-element analysis of soft ground improved by geotextile-encased granular columns
Authors: Hosseinpour I. , Almeida M. S. S. , Riccio M.
Published: November 2015

A full-scale test embankment was constructed on a soft deposit (Su < 20 kPa) improved by geotextile-encased granular columns to assess its serviceability performance for a nearby stockyard foundation. The behaviour of the improved foundation was monitored by means of instrumentation with respect to surface settlements, excess pore pressures, total vertical stresses acting on the top of the encased column and surrounding soft soil as well as geotextile radial deformation. Two-dimensional finite-element analysis was performed using an axi-symmetric unit cell, and then the results were compared with field measurements. It was observed that the soil arching progressed during post-construction due to a decrease in apparent stiffness of soft clay from quasi undrained to drained stiffness. Furthermore, there was a difference in settlement between the top of the encased column and the surrounding soft soil, midpoint between the columns, which increased during both construction and consolidation stages. A measured relation was also found to correlate the geotextile expansion with the maximum settlement occurring below the embankment.
Interface shear properties of geosynthetics and construction and demolition waste from large-scale direct shear tests
Authors: Vieira C. S. , Pereira P. M.
Published: November 2015

In recent years environmental sustainability has demanded a progressive increase of waste recycling in general and waste value-added utilisation in the construction industry in particular. As regards the application of construction and demolition wastes (C&DW) in geotechnical works, it has been noticed that the use of recycled aggregates is found mostly in road construction. Value-added utilisation of C&DW in geosynthetic-reinforced structures is almost an unexplored field. This paper presents the results of physical, mechanical and environmental characterisation of recycled C&DW, as well as the direct shear behaviour of three recycled C&DW–geosynthetic interfaces. The C&DW material was collected from a recycling plant and came from the demolition of single-family houses and the cleaning of land with illegal deposits of C&DW. Two geogrids and one geocomposite reinforcement (high- strength geotextile) were used to assess the behaviour of C&DW–geosynthetic interfaces. The environmental characterisation of the C&DW, carried out through leaching tests, did not show environmental concerns. Direct shear test results have demonstrated that properly selected and compacted C&DW can exhibit shear strength similar to natural soils. The coefficients of interaction achieved for C&DW–geosynthetic interfaces compare well with those reported in the literature for soil–geosynthetic interfaces under similar conditions, which supports the feasibility of using these recycled materials as backfill in geosynthetic-reinforced structures.
Effects of cracks and desiccation on the bearing capacity of soil deposits
Authors: Lozada C. , Caicedo B. , Thorel L.
Published: November 2015

Large cracks in soil deposits have been identified in many locations in different parts of the world. Various studies have examined processes of crack formation and interactions with atmospheric conditions, but the effects of cracking on bearing capacity have received little attention. This study used a geotechnical centrifuge to simulate the influence of cracks and desiccation on the bearing capacity of shallow circular foundations. The results indicate that there are different failure mechanisms depending on the depth of the cracks.
Fractal analysis for dynamic failure characteristics of granite induced by mechanical–thermal loading
Authors: Liu S. , Xu J. Y.
Published: November 2015

High temperatures and impact loads significantly influence the fragmentation characteristics of rock. Impact compression tests, based on the coupled effect of different temperatures and different rates of impact load, were conducted on granite to study variations in dynamic fragment distribution, fractal dimension and dynamic failure shape. The different dynamic fragmentation characteristics displayed by granite under the coupled effect of high temperature and impact load were then examined. With rising temperature, the size of the granite fragments at the same rate of impact load demonstrated a trend of first increasing and then decreasing. The results also showed that high temperature has a significant effect on the fractal distribution of rock fragments while the combined effect of high temperature and impact load results in differences in the fragment distributions of rocks.
Numerical analysis of electro-osmosis consolidation: a case study
Authors: Yuan J. , Hicks M. A.
Published: November 2015

A numerical model for the design and analysis of electro-osmosis consolidation in soft clay is used to study a well-documented full-scale field test. The large-strain model, which considers coupled electro-osmosis flow, hydraulic flow and electric density flow in a deformable elasto-plastic porous medium, is briefly introduced first. It is then used to analyse the field test, including a sensitivity analysis to study the uncertainty of the model in simulating the test. The results of the numerical analyses are found to be consistent with measurements of the ground settlement profile. Moreover, the sensitivity results illustrate that the soil improvement induced by electro-osmosis consolidation is sensitive to the electro-osmosis conductivity, and that consideration of the voltage drop that occurs at the electrodes during the test is necessary.
A comparison of full profile prediction methods for a spudcan penetrating sand overlying clay
Authors: Hu P. , STANIER S. A. , WANG D. , CASSIDY M. J.
Published: November 2015

Spudcans are the traditional footings used for offshore mobile jack-up rigs. However, the installation of spudcans in sand overlying clay may lead to punch-through failure, which can cause serious damage to the jack-up rig and endanger personnel. This article compares three new methods proposed in the literature and an interpretation of the International Organization for Standardization (ISO) guideline for predicting the full penetration resistance profile. The penetration resistance profile for each of the methods is characterised by two key calculations: the peak resistance in the sand and the bearing capacity within the underlying clay. The punch-through distance – an indicator of the potential for and severity of punch-through failure – is estimated from these calculations. In comparison with 71 geotechnical centrifuge tests, the ISO guideline provides poor predictions, consistently underestimating the peak resistance in the sand and the underlying bearing capacity in the clay. Although all three of the new methods provide a superior response, by assessing the accuracy, scatter and geometric skew of the predictions, two of the methods are shown to be biased in at least one of the key calculations used to define the penetration resistance profile, thus producing bias in the prediction of the punch-through distance. However, one method yields largely unbiased predictions.
Soil response in the wake of dynamically installed projectiles
Authors: O'Beirne C. , O'Loughlin C. D. , Gaudin C.
Published: November 2015

The soil response in the wake of dynamically installed (free-fall) projectiles is poorly understood, notably with respect to the potential for the hole the projectile creates during dynamic penetration to remain open. The work reported in this paper considered this problem through centrifuge tests in which the impact of free-falling projectiles on the surface of kaolin clay was captured using a high-speed video camera. The video observations show that hole closure may occur at the same rate as the projectile penetrates, or may remain open, either fully or partially. The paper shows that hole closure is controlled by a dimensionless strength ratio, expressed in terms of the undrained shear strength at the rear of the embedded projectile, the projectile diameter and the effective unit weight of the soil. The centrifuge data agree well with an expression derived from tests on undrained, constant rate of penetration spherical penetrometer tests, demonstrating that hole closure is controlled by soil backflow at the rear of the projectile, regardless of the geometrical aspect ratio (length/diameter) of the projectile. This expression can then be used to assess hole closure assumptions made in dynamic penetration analyses, by comparing the final embedment depth with the calculated transitional depth for soil backflow.
Strength reduction finite-element limit analysis
Authors: Krabbenhoft K. , Lyamin A. V.
Published: November 2015

A procedure for strength reduction analysis using finite-element limit analysis is presented. The scheme is completely general and does not require decision making regarding the loads needed to drive the system to failure. Rather, the scheme is based on the ability of modern interior-point methods to detect infeasibility in a controlled and reliable manner. The new scheme is illustrated by an example involving a strip footing on top of a slope.
A particle model for rockfill behaviour
Authors: Tapias M. , Alonso E. E. , Gili J.
Published: November 2015

Particle crushing has been introduced into a discrete model for rockfill aggregates by a novel approach which combines a closed-form solution for stress distribution inside particles and a crack propagation criterion derived from fracture mechanics concepts. Two breakage modes are simulated: a local contact crushing and an equal volume splitting. The occurrence of both modes derives from experimental observations. Three main parameters control the model performance: contact stiffness, basic friction angle of the particle material and the particle toughness. Contact stiffness and friction were determined by experiments. A large diameter oedometer test on hard limestone gravel was successfully simulated. The simulation included the prediction of the compression response and the evolution of grain size distribution. Rock toughness and basic friction angle were determined independently from the oedometer results. Subsequently, large-scale triaxial tests on the same material and different grain size distributions were simulated. Model parameters fitting the oedometer test were maintained unchanged. The predicted triaxial response (deviatoric stress–strain response, volumetric behaviour and final grain size distribution) was close to actual measurements.
Static and cyclic undrained response of square embedded foundations
Authors: Ntritsos N. , Anastasopoulos I. , Gazetas G.
Published: November 2015

Results of a three-dimensional finite-element study for the effect of embedment on the undrained bearing capacity, the elastic stiffness, and the cyclic behaviour of square-in-plan foundations are presented. Uniaxial horizontal (Q) and pure-moment (M) limit loads, as well as the respective elastic stiffnesses (KHH and KMM) are obtained, and simplified models are developed to interpret the observed trends. The substantially different role of embedment in increasing elastic stiffness and in increasing ultimate loads is interpreted in simple soil mechanics terms. Extensive comparisons are made with the two-dimensional results for a strip foundation. Combined (QM) loading capacities are obtained and presented as ‘interaction’ diagrams; the significance of the vertical load (N) is also addressed. The importance of the type of contact between the foundation interfaces (vertical or horizontal) with the surrounding or underlying soil is explored. A substantial reduction in all capacities is shown when the interfaces are tensionless and of limited shear (sliding) resistance (TSI), compared with the capacities for the ideal case of fully bonded contact (FBC). The cyclic moment–rotation (M–θ) response of embedded foundations carrying a simple slender structure is investigated parametrically. It is found that the monotonic loading curves provide approximately the envelope for the cyclic M–θ loops. But the shape of these loops and the ensuing settlement of the foundation are both functions of the factor of safety (FSV) against vertical bearing capacity. In case of surface and shallowly embedded foundations with high values of FSV (i.e. with light loading or on very stiff soil) the loops pass nearly through the centre (M = θ = 0) of the coordinate axes and the residual settlement is negligible; both are a consequence of the predominantly geometric non-linearity in the form of separation of the walls and uplifting of the base from the soil. On the contrary, with low FSV values (heavy loading or soft soil) and deeper relative embedment, broad hysteresis loops and accumulating settlement are the rule – a product of material inelasticity of the soil, under limited soil–foundation detachment.
Observation-guided constitutive modelling for creeping landslides
Authors: Oberender P. W. , Puzrin A. M.
Published: November 2015

Creeping landslides are common in mountainous areas, causing significant damage to buildings and infrastructure. The major difficulty in modelling of these landslides is the inability of laboratory tests to reproduce adequately the macro behaviour in the creeping soil masses. The proposed approach of observation-guided constitutive modelling addresses this issue by considering a creeping landslide as a series of macro elements, where monitoring of displacements and pore water pressures allows the derivation of suitable constitutive models and their parameters. The paper proposes three generalised models describing the behaviour of pore water pressures, sliding layer and slip surface, which can be adapted to fit the observational data. The three models are integrated into the boundary value problem, the solution of which helps to explain the evolution of the landslide and to predict its future behaviour using probabilistic approaches. When applied to the St Moritz-Brattas landslide in Switzerland, the calibrated landslide models proved to be successful in describing the complex behaviour of all three distinctive regions of the landslide. The paper also explores possible ways for predicting the landslide reaction to extreme rains and forecasting the long-term displacement evolution in the vicinity of the Leaning Tower of St Moritz, which will be critical for planning its future stabilisation.
Thermo-poro-mechanical analysis of landslides: from creeping behaviour to catastrophic failure
Authors: Alonso E. E. , Zervos A. , Pinyol N. M.
Published: November 2015

The scope of the paper encompasses planar and compound sliding motions, which may exhibit creeping behaviour during a certain period but may evolve to a very rapid motion. Thermo-mechanical interactions, at the scale of the sliding surface, are accepted as a critical aspect to explain these motion phases and their relationship. The sliding kinetics and global equilibrium are described at a large scale and the evolving shearing strength at the sliding surface derives from the local analysis of the shearing band and its vicinity. Pore pressures, temperatures and related variables are calculated by resolving a set of balance equations. The paper describes the transition from creeping motions to a rapid event. Results are found in terms of dimensionless numbers. Calculation of the slide evolution requires special numerical techniques described in the paper. Band permeability is found to be the dominant property controlling the triggering of fast motions. The creeping stage and the eventual slide blow-up are intimately linked. This relationship is explored in the paper. The models presented can be readily used to back-analyse relevant case histories or, in principle, even to carry out predictive modelling, provided an adequate calibration is available for the material parameters.
Laboratory modelling of T-shaped soil–cement column for soft ground treatment under embankment
Authors: Yi Y. , Liu S. , Puppala A. J.
Published: November 2015

This technical note presents a laboratory modelling of a T-shaped soil–cement column for soft ground treatment under an embankment, and compares it with a conventional column. A thick sand layer was placed between the column-treated ground and the loading plate to simulate the embankment effect, and the stress, excess pore pressure and settlement of the ground were analysed. Since the T-shaped column had an enlarged column cap, it took more applied load than the conventional column, resulting in less stress on the soil. This effect reduced the soil settlement and differential settlement of the ground, and increased its consolidation rate.
New in situ techniques for measuring the properties of root-reinforced soil – laboratory evaluation
Authors: Meijer G. J. , Bengough A. G. , Knappett J. A. , Loades K. W. , Nicoll B. C.
Published: November 2015

Mechanical root reinforcement is one of the mechanisms by which vegetation enhances slope stability. Common approaches to quantify this effect include either in situ shear box testing or destructive root sampling combined with a theoretical model to estimate reinforcement parameters. Both approaches, however, are time consuming. Here four new in situ techniques are evaluated to quantify mechanical root reinforcement and then compared under laboratory conditions. All four methods yield distinct results in soils reinforced with woody root analogues (acrylonitrile butadiene styrene rods), fine root analogues (polypropylene fibres) or stones. Two methods (adaptations of penetrometer testing, dubbed ‘blade penetrometer’ and ‘pull-up’) are suitable for spatially locating rooted zones and individual roots, while the other two (‘pin vane’ and ‘corkscrew’ extraction) demonstrate potential for directly quantifying the rooted soil stress–strain behaviour. These simple methods are suitable for use on difficult-to-access terrain where many measurements are needed to quantify spatial and temporal variability of root-zone properties for geotechnical calculations. The techniques are quicker to use than conventional methods and so should improve the reliability of slope stability predictions.
On the volumetric strain–time curve patterns of dredged clays during primary consolidation
Authors: Zeng L.-L. , Hong Z.-S. , Cui Y.-J.
Published: November 2015

Thirteen one-dimensional consolidation tests with step loading were performed on dredged clays reconstituted at different initial water contents. Both vertical deformation and pore pressure were measured during primary consolidation, which refers to the time-dependent compression process associated with the dissipation of pore pressure. The pore pressure changes were investigated by considering the maximum and the residual values. The development of compression during pore pressure dissipation was analysed to identify the change patterns in volumetric strain–time curves. Three types of change patterns were found during the primary consolidation, and the remoulded yield stress was found to be the key factor in classifying the change patterns. The inflexion point is absent for types 1 and 2, indicating that the end of primary consolidation cannot be determined by the commonly used Taylor and Casagrande methods. Type 3 shows an inverse ‘S’ shape, suggesting that the end of primary consolidation determined based on the compression–time curves occurs before the completion of pore pressure dissipation.
Dynamic installation of OMNI-Max anchors in clay: numerical analysis
Authors: Kim Y. H. , Hossain M. S.
Published: November 2015

This paper reports the results from three-dimensional dynamic finite-element analysis undertaken to provide insight into the behaviour of OMNI-Max™ anchors during dynamic installation in non-homogeneous clay. The large-deformation finite-element analyses were carried out using the coupled Eulerian–Lagrangian approach, modifying the simple elastic–perfectly plastic Tresca soil model to allow strain softening, and incorporate strain-rate dependency of the shear strength using the Herschel–Bulkley model. The results were validated against field data prior to undertaking a detailed parametric study, exploring the relevant range of parameters in terms of anchor mass, impact velocity and soil strength. To predict the embedment depth in the field, an improved rational analytical embedment model, based on the total energy method, was proposed, with the large-deformation finite-element data used to calibrate the model.
Seismic performance of special reinforced concrete coupling beams with diagonal reinforcement and headed bars
Authors: Chun Young Soo , Chang Kug Kwan
Published: November 2015

Special reinforced concrete coupling beams in high-seismic-risk regions require specific diagonal bundled reinforcement details that must be strictly followed to ensure proper structural performance. However, when these details are applied to coupled shear wall structures, the coupling beams' width must match the width of the walls, resulting in a complicated rebar layout and difficulty in on-site installation. Especially when applied with special shear wall structures, the joint between the coupling beam and the shear wall results in extremely complex reinforcement details that are almost impossible to install on site. With a view to overcoming such problems, this paper evaluates and reports on seismic resistance performance tests performed on coupling beams with a single diagonal reinforcement bar together with headed bars (DHB) reinforcement details, as a proposed alternative solution. Test results show that the test specimen HB75, in which the headed bars substituted for 75% of the capacity of the diagonal reinforcing bundled bars, had superior ductility and energy dissipation capability, as well as lower strength and stiffness degradation compared to other test specimens. Thus, this research indicates that the headed bars can be a practical alternative to hoops of diagonal bundled bars for confining concrete in coupling beams.
Strength and performance of steel fibre-reinforced concrete stiffened plates
Authors: Singh Harvinder
Published: November 2015

This paper presents the results of an experimental investigation conducted on full-scale specimens to examine the effect of using steel fibre-reinforced concrete (SFRC) on the strength and performance of rectangular stiffened plates. A comparison of the flexural response of identically designed SFRC and reinforced concrete (RC) stiffened plates is also presented. Both the SFRC and RC plates carried the design load with an adequate load factor. The midspan deflection was found to be well within the limits prescribed by design guidelines. An improved theoretical formulation to predict the ultimate flexural strength and/or the design of rectangular SFRC stiffened plates is also proposed.
Displacement ductility ratio-based flexural design approach of reinforced concrete slender shear walls
Authors: Mun Ju-Hyun , Yang Keun-Hyeok
Published: November 2015

This study established a new flexural design approach for reinforced concrete shear walls based on the displacement ductility ratio. The moment–curvature relationship of a shear wall section was generalised by interpolating the points of yielding, ultimate flexural capacity and 80% of ultimate flexural capacity after the peak point. To estimate the curvature of the shear walls at the post-peak branch, the concrete strain at the extreme fibre was calculated by considering the volumetric index of the lateral reinforcement and the concrete stress reduction factor derived from the stress–strain relationship of confined concrete. The calculated curvature points were converted to lateral displacements using the moment area method associated with the equivalent plastic hinge length. To simply evaluate the displacement ductility ratio of shear walls, an extensive parametric study was conducted in accordance with the above procedure. The proposed moment–curvature relationship and displacement ductility ratio equation for shear walls were verified through comparisons with experimental results compiled from the available literature. Ultimately, the proposed models were applied to the development of a flexural design of shear walls and a design diagram to determine the details of boundary element length for a targeted ductility ratio.
Experimental study on shear-peeling bond strength between a CFRP plate and concrete
Authors: Zhang Wei
Published: November 2015

Diagonal tension cracks in reinforced concrete members adversely affect the performance of flexural members strengthened by externally bonded fibre-reinforced polymer (FRP) materials. The interface between FRP materials and concrete is influenced by both shear and peeling for such conditions. The objective of this study is to understand bond behaviour in carbon FRP plates and concrete systems under a combination of fracture modes (peeling and shear) by double-lap shear bond tests. The specimens were designed for different initial angles at the middle of the specimen to ensure that the interface acts for both shear and peeling conditions. From the test results, the bond behaviour under the combination of fracture modes can be observed by their strain distribution and load–displacement relation. The results also confirm that the tensile load decreases as the peeling angle increases. Moreover, a new calculation method to predict the bond strength between carbon FRP plates and concrete under shear-peeling fracture is proposed and agrees well with the test results.
Impact resilience of multiscale fibre reinforced composites
Authors: Masud Mahadi , Chorzepa Mi Geum
Published: November 2015

This research considered cementitious composites reinforced with macroscale, microscale and nanoscale fibres. Ten test groups including a combination of the multiscale fibres (steel fibres, polyvinyl alcohol (PVA) fibres and carbon nanofibres (CNFs)) were studied. An experimental programme was developed to determine the compressive, tensile and flexural strength as well as impact toughness. This multiscale fibre reinforcement (steel, PVA and CNFs) in normal concrete mixes for practical applications led to a tenfold increase in impact resilience, based on a small-scale repeated impact test performed in this study, and also considerably enhanced the tensile strength of the cementitious composites. On the other hand, cementitious composites singly reinforced with nanoscale CNFs in normal concrete mixes including coarse and fine aggregates showed negligible improvements in impact toughness and tensile strength. Three-point bending tests on reinforced concrete beam specimens showed that the macroscale structural performance of the concrete members was enhanced with the addition of multiscale fibres. The toughness or energy absorption capability increased by 29%. It is therefore concluded that multiscale fibre reinforcement, including CNFs, has the potential to reduce the projectile–target collision force due to increased ductility of the concrete members and to alleviate concrete spalling resulting from projectile penetration on account of increased toughness.
An experimental study on the seismic performance of medium- to low-rise RC structures controlled by both shear and flexure
Authors: Lee Kang Seok , Kee Seong-Hoon , Lee Sang-Sup , Park Keum-Sung
Published: November 2015

The lateral-force-resisting systems (LFRSs) of many medium- to low-rise reinforced concrete (RC) buildings are composed of members that may be vulnerable to pre-emptive shear failures, depending on whether their shear strengths are sufficient to develop their flexural strengths (hereafter referred to as dual LFRSs). Therefore, such buildings have a lateral strength associated with the strengths of components, and the component strengths may be governed by both shear and flexure. At present, there is no effective way of assessing the relationship of component strengths between the shear and flexure of a RC building having a dual LFRS. Several studies have investigated the seismic performance of RC buildings controlled by both shear and flexure, but the scope of these studies was very limited and they focused mainly on analytical research. In this study, a series of pseudo-static reversed cyclic loading tests was conducted in the laboratory to investigate seismic performance in terms of the structural non-linear behaviour and lateral-force-resisting mechanism at the ultimate state of a dual LFRS. The results of this research provide fundamental information for the proposal of hysteresis characteristics and a practical guideline for evaluating the seismic performance of medium- to low-rise RC buildings comprising members failing in both shear and flexure.