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- Vibration measurement, Biodynamic properties of human whole-body, Structural vibration induced by rhythmic crowd loads, Design for efficient structures using mechanics concepts, Loads induced by human movements, Civil and Environmental Engineering, and 5 moreEngineering, Civil Engineering, Structural Engineering, Geotechnical Engineering, and Sustainable Water Resources Managementedit
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The bearing capacity of closely spaced shallow footings alters with their spacing and the shape of footing. In this study, the bearing capacity and settlement of two adjacent footings constructed on a sand layer are investigated. The... more
The bearing capacity of closely spaced shallow footings alters with their spacing and the shape of footing. In this study, the bearing capacity and settlement of two adjacent footings constructed on a sand layer are investigated. The effect of different footing shapes including square, circular, ring and strip on sandy soil is captured in the calculations. The investigations are carried out numerically using PLAXIS-3D software and analytically employing conventional settlement equations. For this purpose, foundations are modelled in the program with practical dimensions and various spacing ratios ranging from 1 to 5. The spacing ratio is defined as the centre-to-centre distance to the width of foundations (S/B). Overall, 24 models are analyzed; and the results are compared and discussed in detail. It can be concluded that the presence of adjacent foundation leads to the reduction in bearing capacity for round shape footings while it can increase the bearing capacity of rectangular f...
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The notion of sustainable and eco-friendly infrastructures is gaining impetus in the geotechnical engineering research field. Nowadays, employing recycled or waste materials, obtained from the natural sources, are widely used as an... more
The notion of sustainable and eco-friendly infrastructures is gaining impetus in the geotechnical engineering research field. Nowadays, employing recycled or waste materials, obtained from the natural sources, are widely used as an alternative method in construction in recognition of the green concept. It is evident that transport infrastructure projects require large amounts of materials and natural resources and consume large quantities of energy. On the other hand, large volumes of wastes are produced daily. In this paper, the beneficial effects of certain agricultural, domestic, industrial, construction, mineral and marine wastes in geotechnical applications, particularly in soil stabilization are discussed. Both methods of treatment are applied to improve the engineering properties of soil to make it suitable for construction. Another goal of this paper is to make a comparison between the effects of different types of waste materials for improving weak soil, and highlight the c...
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ABSTR.ACT: Tn \:111" pITper, the effects of uncertainties of ~mear zone charadelistics induced by installation oCprd.abricaled vertical drains on the pre1oadir.g design are numerically investigated, FLAC 2D finite difference software... more
ABSTR.ACT: Tn \:111" pITper, the effects of uncertainties of ~mear zone charadelistics induced by installation oCprd.abricaled vertical drains on the pre1oadir.g design are numerically investigated, FLAC 2D finite difference software with additional deve10ped subroutines has bee~:employed to conduct the numerical simulations. TIle finite difference analyses have been verit1ed using a case study. FLlrthcnuorc, a'.coinprehensive parametric study is conducted to investigate the inilue-nce of iimear zone permeability and extent on the model prcciictl0l1S. Re~lllts of thi::; study indicate thaI the assumplive properties for smear zone characteristics may result in inaccurate predictions -of ground dciollllaLions and pore '\-vater pres;;ures. This may lead to early removaL of the surcharge in thc construction process causing excessive post construction settlcment ft is recommended to practising cngineers to usc results oftrial prdoading to back calculate the required smear zo...
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XML is very attractive for platform independent information exchange, and hence XML streams are becoming very common. In this paper, we discuss and propose an efficient approach to deal with XML streams. Instead of using finite-state... more
XML is very attractive for platform independent information exchange, and hence XML streams are becoming very common. In this paper, we discuss and propose an efficient approach to deal with XML streams. Instead of using finite-state automata, we use parse trees in our approach. Moreover, we try to release results to users as soon as possible, through early predicate evaluation. The implemented system accepts for-let-where XQuery queries. After conducting experiments to examine our approach for processing XML streams, we got good results which demonstrate the efficiency, applicability and effectiveness of our approach.
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A fully coupled flow-deformation model is presented for the behaviour of unsaturated porous media. The governing equations are derived based on the equations of equilibrium, effective stress concept,... more
A fully coupled flow-deformation model is presented for the behaviour of unsaturated porous media. The governing equations are derived based on the equations of equilibrium, effective stress concept, Darcy's law, Henry's law, and the conservation of fluid mass. Macroscopic coupling between the flow and deformation fields is established through the effective stress parameters. The microscopic link between the volumetric deformations
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A fully coupled flow-deformation model is presented for the behaviour of unsaturated porous media. The governing equations are derived based on the equations of equilibrium, effective stress concept,... more
A fully coupled flow-deformation model is presented for the behaviour of unsaturated porous media. The governing equations are derived based on the equations of equilibrium, effective stress concept, Darcy's law, Henry's law, and the conservation of fluid mass. Macroscopic coupling between the flow and deformation fields is established through the effective stress parameters. The microscopic link between the volumetric deformations
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This study describes the effect of unsaturation at a drain boundary on the behaviour of a single prefabricated vertical drain subjected to vacuum preloading based on a two-dimensional plane strain finite element model incorporating the... more
This study describes the effect of unsaturation at a drain boundary on the behaviour of a single prefabricated vertical drain subjected to vacuum preloading based on a two-dimensional plane strain finite element model incorporating the modified CamClay model. Unsaturation of soil adjacent to the drain can occur due to mandrel withdrawal or application of vacuum pressure through prefabricated vertical band drains (PVDs). Following initial laboratory simulation in a large-scale radial drainage consolidometer, the authors have attempted to explain the observed retardation of pore pressure dissipation through a series of models, which consider the effect of unsaturation at the drain-soil interface. The results indicate that the introduction of an unsaturated soil layer adjacent to a PVD improves the accuracy of numerical predictions. Lastly, a multidrain analysis is conducted to study the behaviour of an embankment stabilized with vertical drains subjected to vacuum preloading, and the...
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The use of modified asphalt binders has become much more common over the past two decades. Many types of modifier have been used in paving asphalts to enhance the performance of asphalt pavements in a wide range of climates and loading... more
The use of modified asphalt binders has become much more common over the past two decades. Many types of modifier have been used in paving asphalts to enhance the performance of asphalt pavements in a wide range of climates and loading conditions. Among various asphalts binder modifiers, the recycled crumb rubber has been used very successfully for many years. Generally in production of CRM binder, mixing and compaction temperature is determined by measuring of binder viscosity. The ordinary method used for viscosity measurement of unmodified binder leads to a very high Mixing and Compaction Temperature (MCT) for CRM binder. The aims of this paper are to identify, develop and give some recommendations on a reliable laboratory approach for blending of CRM with binder, as well as introducing appropriate laboratory test methods for optimisation of MCT of crumb rubber modified binder asphalt.
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Intelligent compaction (IC) is an emerging technology for efficient and optimized ground compaction. IC combines the roller-integrated measurements with the Global Positioning System (GPS), which performs the real-time quality control and... more
Intelligent compaction (IC) is an emerging technology for efficient and optimized ground compaction. IC combines the roller-integrated measurements with the Global Positioning System (GPS), which performs the real-time quality control and assurance during the compaction work. Indeed, IC technology is proven to be capable of providing a detailed control system for compaction process with real-time feedback and adjustment on full-area of compaction. Although roller manufacturers offer typical recommended settings for rollers in various soils, there are still some areas needing further improvement, particularly on the selection of vibration frequency and amplitude of the roller in soils experiencing significant nonlinearity and plasticity during compaction. In this paper, the interaction between the road subgrade and the vibrating roller is simulated, using the three-dimensional finite element method capturing the dynamic responses of the soil and the roller. The developed numerical model is able to simulate the nonlinear behavior of soil subjected to dynamic loading, particularly variations of soil stiffness and damping with the cyclic shear strain induced by the applied load. In this study, the dynamic load of the roller is explicitly applied to the simulated cylindrical roller drum. Besides, the impact of the frequency and amplitude on the level of subgrade compaction is discussed based on the detailed numerical analysis. The adopted constitutive model allows to assess the progressive settlement of ground subjected to cyclic loading. The results based on the numerical modeling reveal that the roller vibration characteristics can impact the influence depth as well as the level of soil compaction and its variations with depth. The results of this study can be used as a potential guidance by practicing engineers and construction teams on selecting the best choice of roller vibration frequency and amplitude to achieve high-quality compaction.
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The effects of the fracture aperture and orientation on the behaviour of weak rock were numerically investigated using discrete element method (DEM). In this study, the mechanical behaviour of the intact and fractured rock specimens was... more
The effects of the fracture aperture and orientation on the behaviour of weak rock were numerically investigated using discrete element method (DEM). In this study, the mechanical behaviour of the intact and fractured rock specimens was simulated by adopting the discontinuum based software PFC3D. The rock specimens with various fracture apertures and orientations were replicated, and the effects of these two fracture characteristics were studied through triaxial tests. The flat-joint model was employed for simulating the stress-strain behaviour of intact rock and had the ability to reproduce the cementation effect. The smooth-joint contact model was utilised to simulate the sliding effect of the fractures. The effects of five different fracture orientations were investigated in the combination of three different fracture aperture categories, namely very tight, open, and moderately wide. It can be concluded that the strength of the fractured weak rock specimens reduces as the fracture aperture width increases. The amount of alternation in strength and deformability that were contributed by fracture apertures differed with the orientations of the fracture. With the fracture orientation that was parallel to the deviatoric loading, the effect of fracture aperture on the strength and deformability of the specimens was less evident.
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Controlled modulus columns (CMC) ground improvement technique is an attractive geotechnical solution for modification of soft soils. This technique uses a displacement auger during column installation, aiming to reduce the construction... more
Controlled modulus columns (CMC) ground improvement technique is an attractive geotechnical solution for modification of soft soils. This technique uses a displacement auger during column installation, aiming to reduce the construction cost and disposal of excavated materials. However, lateral and vertical soil movement induced by the installation process may pose potential risks to the adjacent previously installed columns. Only a handful of studies have been attempted in quantifying such effects. This paper presents the results of a numerical investigation on the effects of CMC installation sequence on the already installed columns using the three-dimensional finite difference software package FLAC. The results indicate that the installation sequence should be taken into account in the design process to minimise any adverse effects of installing new CMCs on the existing columns. RÉSUMÉ : La technique d'amélioration du sol des colonnes à module contrôlé (CMC) est une solution g...
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In this paper weak rock specimens with different individual fracture lengths are numerically simulated using the discrete element method (DEM). Effects of micro or macro-mechanical responses of intact and fractured specimens subjected to... more
In this paper weak rock specimens with different individual fracture lengths are numerically simulated using the discrete element method (DEM). Effects of micro or macro-mechanical responses of intact and fractured specimens subjected to triaxial test have been studied. Various individual fracture lengths with a given fracture density within the weak rock specimens were reproduced using the particle flow code in three-dimension software (PFC3D). Different lengths of fractures were simulated by altering the size of each fracture to give insight over the influence of continual fractures and non-persistent fractures within bonded assemblies. As expected, for a given fracture density the individual fracture length affected the strength and deformability of rock mass. For an individual fracture length to specimen width ratio (the normalized fracture length) less than a limiting value, the effects of the individual fracture length on the stress-strain behaviour of rock specimens were more...
A wide range of teaching strategies aiming to motivate and develop deep learning approaches in engineering students and to turn students into active, reflective and long-life learners have been previously explored by researchers and... more
A wide range of teaching strategies aiming to motivate and develop deep learning approaches in engineering students and to turn students into active, reflective and long-life learners have been previously explored by researchers and educators [1,2]. Moreover, it is well-established in the literature that different types of students are more motivated by one teaching/learning strategy than another and the ability of lecturer for combining various activities that engage different types of students at different moments of the class is the key to successful implementation of any strategy [2]. However, effectiveness of research-inspired teaching/learning strategies for engaging a wide range of students with different motivation, attitudes and learning styles has not been adequately investigated [3]. Furthermore, application of research-inspired teaching strategies for developing graduate attributes such as teamwork, problem-solving skills and long-life learning attitude remains largely u...
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This study presents a new simple equation for prediction of pile group efficiency considering the effect of tapering angle in cohesionless soil under vertical loading. Firstly, a simple analytical relationship based on the mathematical... more
This study presents a new simple equation for prediction of pile group efficiency considering the effect of tapering angle in cohesionless soil under vertical loading. Firstly, a simple analytical relationship based on the mathematical definition of the pile group efficiency is developed. However, the effect of tapering angle is captured by defining a new geometry efficiency coefficient associated with the shaft vertical bearing component of tapered piles. Thereafter, a mathematical equation is developed by taking into account the shaft vertical bearing ratio and the new geometry efficiency coefficient. On the other hand, a numerical analysis is performed for modelling a single bored cylindrical pile and a tapered pile with the same volume as well as bored tapered pile groups to validate the proposed mathematical equation. The UBC sand constitutive model is adopted for the modelling of piles in loose Cambria sand. Subsequently, the load-displacement diagrams of single and group of piles are obtained. Then, the bearing capacities of cylindrical and tapered bored piles both as single and group are computed and compared, using a specific settlement criterion. Besides, the friction resistance ratio and the shaft vertical bearing ratio are separated, applying numerical methods. Having calculated the ratios of various components of bearing capacity, pile group efficiencies can be obtained from both numerical and mathematical models. The results show that the proposed equation can predict the pile group efficiency incorporating the tapering angle as well as other influencing parameters as a simple and novel relationship.
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AbstractFor a foundation to perform safely, the ultimate strength of each pile must satisfy the structural and geotechnical requirements. Pile load testing is considered to be a direct method for d...
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ABSTRACT Monopiles are used in piers as mooring or berthing dolphins. This article reports the results of full-scale lateral loading tests on monopiles constructed as dolphins in the Pars Special Economic Energy Zone in southern Iran. The... more
ABSTRACT Monopiles are used in piers as mooring or berthing dolphins. This article reports the results of full-scale lateral loading tests on monopiles constructed as dolphins in the Pars Special Economic Energy Zone in southern Iran. The length and diameter of the monopiles were approximately 40 m and 2 m, respectively. Lateral loading tests of such large monopiles are not commonly undertaken, thus there is limited data available. This research developed a lateral analysis of piles computer code to examine analytical methods for pile analysis. Appropriate models were introduced resulting in accurate predictions in the analysis of lateral loaded piles. The results showed that traditional p-y curves and strain wedge models calculate larger pile head deflection in comparison to the field test data and therefore local calibration is essential.
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ABSTRACT In this study, effects of two types of geofibers, namely polypropylene and recycled carpet, on three dimensional shrinkage properties of cement treated kaolinite and bentonite clays are investigated. Cement treated clay specimens... more
ABSTRACT In this study, effects of two types of geofibers, namely polypropylene and recycled carpet, on three dimensional shrinkage properties of cement treated kaolinite and bentonite clays are investigated. Cement treated clay specimens were prepared with cement contents of 5, 10, and 15 % by weight of dry soil for kaolinite samples, and 30, 40 and 50 % for bentonite samples. To investigate and understand the influence of different fiber types and contents, three different percentages of fiber content (i.e. 0.1, 0.2 and 0.5 % polypropylene fibers; and 0.5, 0.75 and 1 % carpet fibers) were adopted. The results of shrinkage tests on 126 cylindrical samples of cement treated clay with various cement and fiber contents were analysed to understand the relationships between these parameters and the shrinkage percentage of treated soil. Results of this study indicate that combination of cement and fiber is effective in reducing the volume change of clayey soils undergoing drying process. In the applied ranges of cement and fiber contents, the influence of cement addition on the shrinkage reduction is more significant than the addition of fibers for the treated kaolinite. However, addition of fibers in curtailing the shrinkage of bentonite clay is more significant than the cement addition.
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ABSTRACT The growing trend in the application of direct displacement-based or performance-based design, lays more emphasis on the precise prediction of design parameters such as the inter-storey drift controlling the performance level of... more
ABSTRACT The growing trend in the application of direct displacement-based or performance-based design, lays more emphasis on the precise prediction of design parameters such as the inter-storey drift controlling the performance level of the structure. Practising engineers employ different methods to record the inter-storey drifts in time-history approach mainly based on the maximum lateral deformation of the structure. In this study, a 15-storey concrete moment resisting building is designed using time-history analysis. Then reliability and accuracy of each method in predicting the maximum inter-storey drifts under the influence of three earthquake records, namely 1995 Kobe, 1994 Northridge and 1940 El Centro earthquakes, are investigated. Results clearly indicate that to choose the most critical drift to evaluate the performance level of structures, the absolute maximum drift over time should be calculated. Other methods based on the maximum storey deflection may result in unconservative design.