Showing papers in "International Journal of Geomate in 2013"
TL;DR: In this article, a sewage sludge ash (SSA) from a waste water treatment plant in Eastern United States was characterized in order to investigate and demonstrate potential reuse applications for the ashes produced by this plant.
Abstract: In this paper sewage sludge ash (SSA) refers to ash material product of incineration of municipal and industrial sewage water. SSA from a waste water treatment plant in Eastern United States was characterized in order to investigate and demonstrate potential reuse applications for the ashes produced by this plant. To date most research on reuse applications for ash materials has focused largely on coal-sourced ashes such as fly ash or bottom ash. In contrast very little research has been reported on SSA, which typically will have important differences with coal-based ashes in terms of physical and chemical composition and cementitious properties. This paper presents the results of an elemental and morphological characterization as well as a demonstration of clay brick admixture and soil stabilization admixture reuses applications.
22 citations
TL;DR: In this paper, the authors investigated the long-term behavior of excavated loess in embankments and found that preloading to 25kPa before flooding provided the maximum degree of densification, and water-retention properties were reproducible upon wetting-drying seasons.
Abstract: The re-use of excavated loess in embankments needs a good understanding of its long-term mechanical response. Among the many collapse controlling factors, stress and hydraulic history are of significant importance as certain combination of these can alter the packing state to great extents. However, published works on stress path-packing state interaction is limited to clayey silts, underreporting the contribution of carbonates. Works on hydraulic path-packing state interaction lacks physical evidences for pore distribution, leading to disputes over the variation of air-volume over time and therefore fills' long-term behaviour. Identical artificial loess specimens were incrementally stressed on dry-, wet-, and wetting-surfaces, while microfabric, suction, particle and pore size distribution were recorded. The response of test material (moderately calcareous lightly clayey silt) showed the failure of dry-compaction in restricting the coefficient of consolidation. Wetting at any stress level improved the pore volumes and thus post-drying collapsibility. However, pre-loading to 25kPa before flooding provided the maximum degree of densification. Water-retention properties were deemed reproducible upon wetting-drying seasons for minimum content of 5-20µm size loess constituents. In short, controlled stress-hydraulic paths can guarantee the long-term response of site-won loess embankments.
19 citations
TL;DR: In this paper, the influence of matric suction is taken into account while interpreting the applied stress versus surface settlement (SVS) behavior of in-situ plate load tests.
Abstract: The applied stress versus surface settlement (SVS ) behavior from in-situ plate load tests ( PLT s) is valuable information that can be used for the reliable design of shallow foundations. In-situ PLT s are commonly conducted on the soils that are typically in a state of unsaturated condition. However, in most cases, the influence of matric suction is not taken into account while interpreting the SVS behavior of in-situ PLT s. In addition, the sizes of plates used for load tests are generally smaller in comparison to real sizes of footings used in practice. Hence, in-situ PLT results should be interpreted taking account of not only matric suction but also the scale effects. In the present study, discussions associated with the uncertainties in interpreting the SVS behavior of PLT s taking account of matric suction and scale effect are detailed and discussed.
19 citations
TL;DR: In this article, the smoothed particle hydrodynamics (SPH) method is applied to simulate response of a slope subjected to seismic loading, and the reliability of SPH results was assessed by comparing with experimental data available in the literature.
Abstract: In the past few decades, majority of dynamic behavior of slope have been conducted using the finite element method (FEM). However, earthquakes often cause large deformation and post-seismic soil deformation which are difficult to predict using the FEM due to mesh distortion issues. As an alternative numerical method, the smoothed particle hydrodynamics (SPH) has been recently applied to geotechnical field and showed to be a promising numerical technique to handle large deformation and post-failure behavior of geomaterials. In this paper, taking into consideration of this advantage, the SPH method is applied to simulate response of a slope subjected to seismic loading. Reliability of SPH results was assessed by comparing with experimental data available in the literature. It is shown that the SPH method could qualitatively predict slope failure behavior observed in the experiment.
18 citations
TL;DR: In this paper, an experimental investigation performed to evaluate the soil water characteristic curves of sand/Al-Qatif clay mixtures is presented. And the shape of SWCC curves changes from the unimodel to the bimodal form of soil water characteristics with the increase in clay content indicative of changes in sand/clay mixture micro-and macro-pores.
Abstract: This paper presents an experimental investigation performed to evaluate the soil water characteristic curves of sand/Al-Qatif clay mixtures. Al-Qatif clay is natural expansive clay widely spread in the eastern province of Saudi Arabia. Detailed mineralogical and physical tests were performed on Al-Qatif clay for characterization. Mixtures of sand and Al-Qatif clay were prepared with sand being the base material and with different clay contents (0%, 5%, 10% and 15%). Test results indicate that the shape of SWCC curves changes from the unimodel to the bimodal form of soil water characteristic curve with the increase in clay content indicative of changes in sand/clay mixture micro-and macro-pores.
16 citations
TL;DR: In this article, a case study of peat soil deposits in Surfers Paradise in Australia is presented, where peat soils in the study area are embedded at depth ranging between R.L. -10 to R.S. -19.6 m below the ground surface and it has a thickness ranging from 0.1 to 7.0 m in some locations.
Abstract: This study examines the engineering characteristics and properties of peat soils in coastal environments in Ireland, Italy, Malaysia, Netherlands, Turkey and USA. The engineering properties to be examined are consolidation characteristics, Atterberg limits, density, organic content, shear strength, and moisture content. Moisture content and organic content are good indication of the occurrence of peat soils because these parameters are inherently high in this soil type. In addition, peat soil is highly compressible and is known to be problematic for geotechnical construction. The peat layer has an adverse effect on the long-term settlement of road embankments. A case study of peat soil deposits in Surfers Paradise in Australia will be presented in the paper. Peat soil in the study area is embedded at depth ranging between R.L. -10 to R.L. - 19.6 m below the ground surface and it has a thickness ranging from 0.1 to 7.0 m in some locations. It possesses low shear strength of between 30-40 kPa and the moisture content can be up to 247 %. Four empirical equations have been established for the peat soils and they are compared with those published in the literatures.
16 citations
TL;DR: In this article, the formation mechanism of beachrock in Nago, Okinawa, Japan was investigated and it was shown that evaporation of seawater and/or urease activity of bacteria may have resulted in precipitation of high Mg calcite (HMC), leading to formation of the beachrock, with partial solidification of some sandy specimens.
Abstract: Beachrock is coastal sediment that has been cemented mainly by calcium carbonate within the intertidal zone in tropical and subtropical regions. Man-made beachrock has the potential to inhibit coastal erosion. Considering this important application, we performed field investigations and laboratory tests to understand the formation mechanism of beachrock in Nago, Okinawa, Japan. We performed a needle penetration test, microbial population count and urease activity test, and conducted elemental and mineral analyses of the beachrock and sand. Some microorganisms at the site showed urease activity and the beachrock cement comprised high Mg calcite (HMC). Our investigation showed that evaporation of seawater and/or urease activity of bacteria may have resulted in precipitation of HMC, leading to formation of the beachrock, with partial solidification of some sandy specimens.
16 citations
TL;DR: In this article, a new numerical approach which can be used to simulate the deformation and flexible behavior of the modula r-block retaining wall system is presented. But numerical development for prediction of the large deformation of modular retaining wall bocks is still not advanc ed.
Abstract: Modular-block retaining wall system has been extensively used to stabilize natural and cut- slope. Despite this fact, numerical development for prediction of the large deformation and flexible b ehavior of modular retaining wall bocks is still not advanc ed. To overcome this limitation, this paper present s a new numerical approach which can be used to simulate la rge deformation and flexible behavior of the modula r- block retaining wall system. Herein, soil is modell ed using an elasto-plastic constitutive model, whil e wall blocks are assumed rigidity with full degree of mot ion. A linear contact model is proposed to simulate interaction between soil and wall block. Experiment s were also conducted to validate the proposed nume rical framework. It is showed that the proposed numerical framework can simulate well behavior of the modular- block retaining wall system.
14 citations
TL;DR: In this paper, geotechnical borelogs are compiled from 51 soil investigation reports in the study area and then imported into ArcGIS10 as digital layers and converted into assessable formats by Geographic Information System (GIS).
Abstract: Peat is a highly organic and compressible soil. Surfers Paradise (as a study area) has problematic peat layer which has different thickness at different locations between R.L. -10 to -19.6 m below the ground surface. Buildings in Surfers Paradise are using piled foundations to avoid the high compressibility and low shear strength peat layer. In this paper, geotechnical borelogs are compiled from 51 soil investigation reports in the study area. These borelogs data are then imported into ArcGIS10 as digital layers and converted into assessable formats by Geographic Information System (GIS). This technique has been utilised to produce digital zonation maps for the study area. The application of interpolation techniques allows the production of zonation maps and bring together years of geotechnical data. Standard Penetration Test (SPT) N values have been selected to determine the soil stiffness in the study area. These SPT-N values are then categorised to produce different zonation maps. The occurrence of peat layers can be located using these zonation maps. These GIS-based zonation maps will provide a better overview of subsurface geology, bed rock elevations, and geotechnical properties of the various soil types found in the study area.
14 citations
TL;DR: In this article, the effects of hydrated lime on the engineering properties of interest for road design and construction for three tropical clays, two highly plastic potentially expansive soils from Republic of Sudan and one red tropical “lateritic” soil from South Sudan were studied.
Abstract: The objective of this paper is to study the effects of hydrated lime on the engineering properties of interest for road design and construction for three tropical clays, two highly plastic potentially expansive soils from Republic of Sudan and one red tropical “lateritic” soil from Republic of South Sudan. The studied properties include Atterberg limits, compaction parameters, permeability, CBR, MR and unconfined strength. The effects of compaction energy on the end result compaction material property parameters were studied. Also, the effect of salinity/sodicity on the plasticity and strength of lime stabilized swelling soils was studied. The study showed that lime efficiently reduces the plasticity of the three soils considered and that for the same increment of lime content the reduction in plasticity is higher for montmorillonitic clays compared to kaolinitic clays. The addition of lime to the three soils increased their maximum dry density and reduced their optimum moisture content. Substantial improvement in the strength and compaction characteristics of lime stabilized tropical clays could be expected on increasing the compaction effort. Permeability substantially increased on adding the optimum lime content to the three soils. Lime increased the strength and stiffness of the treated soils and the amount of lime needed to improve lateritic clay soils is less than that needed to improve swelling soils. The MR test results indicate increased stiffness of the lime stabilized kaolinitic clay soils compared to montmorillonitic clays. The increase in salinity/sodicity resulted in decrease of plasticity and increase in strength for the natural untreated and lime treated sodic soil tested.
10 citations
Journal Article•
TL;DR: In this article, the deformation characteristics of sand-gravel mixtures, simulating fine-ballast mixtures were studied using laboratory and DEM-simulated triaxial compression tests.
Abstract: In railway tracks, ballast fouling due to fine materials mixing has been identified as a challenging issue. In this research, deformation characteristics of sand-gravel mixtures, simulating fine-ballast mixtures, were studied using laboratory and DEM-simulated triaxial compression tests. The DEM simulations were done in Yade, an open source developed based on DEM. Initially, void ratio characteristics of sand-gravel mixtures were studied. Then, triaxial compression tests were conducted for the specimens of 50% and 80% of relative densities. The void ratio results indicated that, initially, void ratios decreased with %sands. After reaching the minimum void ratios, void ratios increased with %sands. The triaxial test results indicated that, on average, similar behaviour in stress-strain curves, where, at initial %sands, stress-strain curves became higher and then, stress-strain curves became smaller, though it was slightly different in laboratory tests.
TL;DR: In this article, different methods of slope stability analysis such as kinematic approach and slope mass rating were applied to investigate the potential failure mode and predict the behavior of rock slopes in the future.
Abstract: The Tamborine Mountain area of the Gold Coast, Australia often faces rock slope failures during rainy seasons. To have a better understanding of the factors that may affect the slope stability, several rock slope sites examined in detail to assess the effect of discontinuities formed in the rock masses, and degree of weathering of the rocks on the overall stability of slopes. Different methods of slope stability analysis such as kinematic approach and slope mass rating, were applied to investigate the potential failure mode and predict the behavior of rock slopes in the future. This paper will present results of this work and make comparisons between different methods of rock slope stability analysis.
TL;DR: In this paper, a method of tsunami disaster wastes estimation based on the officially announced data is described. But this method is based on a GIS platform and is not suitable for large-scale disasters.
Abstract: A huge amount of disaster wastes was accumulated along coastline areas of the Tohoku region by tsunami dur ing the 2011 off the Pacific coast of Tohoku Earthquake. Th e total amount of tsunami disaster wastes was estimated to be 26.7 million tons. This corresponds to 50 % of the total amount of the waste of Japan in 2009. Tohoku Earthquake caused widespread serious damage. Since the coastal area o f Tohoku region shapes a saw-toothed coastline, it is difficult to prepare large places for filling these disaster wastes. And a road for carrying to these treatment facilities i s not enough in Tohoku coast line area, most port facilit ies were damaged seriously. This means the dispose of disast er wastes is in extremely difficult in Tohoku region. Since a tsunami height in Shikoku region during nex t Tokai Earthquake or Nankai one will be larger than the Tohoku Earthquake, it can be anticipated that an am ount of disaster wastes in Shikoku is also very large. It i s very important to estimate an amount of tsunami disaster wastes for quick recover and revival of damaged areas. This paper describes a method of wastes amount estimation based on the officially announced data a nalyzed in GIS platform.
TL;DR: In this article, the authors present three case studies of vetiver plantations in slope protection against rain-cut and wind-induced erosion, and find that vetiver grass grows in different soil and climatic conditions of Bangladesh and it is effective for slope protection.
Abstract: River bank erosion and embankment failures happen continuously throughout Bangladesh. From a strictly economic point of view, the cost of remediating these problems is high, and the state budget for such works is never sufficient. This confines rigid structural protection measures to the most acute sections. General reasons of embankment failure are erosion due to rain splash, wave action, overtopping of storm surge. Faulty design, poor maintenance and poor construction also cause failure. The use of cement concrete blocks, stone revetments, geo- bags, and plantation etc. are commonly used for protection of embankment in traditional practices. These materials are expensive and sometimes are not effective to protect the embankments and river bank for an expected design life. On the other hand, slope stability can be augmented by using bio-engineering techniques. Vetiver grass (Vetiveria zizanioides) is being used as an efficient bio-technology for slope protection in many countries, for its special attributes like longer life, strong and long finely structured root system and high tolerance of extreme climatic condition. A few steps have only been taken recently to employ this technique for slope protection purposes in Bangladesh. This paper presents three case studies of vetiver plantation in slope protection against rain-cut and wind-induced erosion. It is found that vetiver grass grows in different soil and climatic conditions of Bangladesh and it is effective for slope protection. Prospect of vetiver plantation in protecting haor low-land is also discussed.
TL;DR: The research object in this paper is to check the purification performance for sludge by checking the experimental way which hydrogen sulfide is reduced at first by using "coagulants" and then the nutrients will be reduced by activating microorganisms.
Abstract: Ocean sludge exerts a very big environmental load to local sea area. Here, attention was paid to micro-bubble technology for application to the purification of the sludge. The important point in this technique is to activate the bacteria existing in the area by micro-bubbles. We had developed a method for decomposing the sludge by using of microorganisms in an aerobic state by micro-bubble. Here, we have also a technique for purification by using "coagulants". So, we proposed the experimental way which hydrogen sulfide is reduced at first by using "coagulants" and then the nutrients will be reduced by activating microorganisms. Here, we used the detergents including enzyme as the microorganism activator. Our research object in this paper is to check the purification performance for sludge by our proposed experimental system. From the results of our experiments, we succeeded in reducing the time needed to purify the sludge, and we obtained the very good performance.
TL;DR: In this article, Gene Expression Programming (GEP) has been used to predict the lateral capacity of piles inserted into clayey soils and subjected to lateral loads, which achieved a coefficient of correlation, r, of 0.95 for training and validation sets and average prediction ratio (APR) of 1.04 and 0.97, respectively.
Abstract: This paper presents the development of a new model to predict the lateral capacity of piles inserted into clayey soils and subjected to lateral loads. Gene Expression Programming (GEP) has been utilized for this purpose. The data used for development of the GEP model is collected from the literature and comprise 38 data points. The data are divided into two subsets: Training set for model calibration and independent validation set for model verification. Predictions from the GEP model are compared with the results of experimental data. The model has achieved a coefficient of correlation, r, of 0.95 for training and validation sets and average prediction ratio (APR) of 0.97 and 1.04 for training and validation sets respectively. The results indicate that the GEP model performs very well and able to predict the pile lateral capacity accurately.
TL;DR: In this article, an artificial neural network was applied to spatially interpolate consolidation properties such as the natural water content, void ratio, plastic index, compression index, and preconsolidation pressure.
Abstract: The spatial distribution of the consolidation properties for a seabed must be appropriately estimated to accurately predict the consolidation settlement due to large-scale reclamation. The soil properties must be estimated at arbitrary positions in the ground from data collected during soil investigation. In this study, an artificial neural network was applied to spatially interpolate consolidation properties such as the natural water content, void ratio, plastic index, compression index, and pre-consolidation pressure. The estimation accuracy of consolidation properties was judged based on four indexes: R2, G, MARE, and SR. The artificial neural network estimated the appropriate consolidation properties with high accuracy; this confirmed the availability of spatial interpolation of consolidation properties by using an artificial neural network.
TL;DR: In this paper, the influence of the chloride salts on the lime-clay reactions was analyzed in terms of changes in void ratio (e), volumetric strain (e1), compression index (Cc), and coefficient of consolidation (cv) which defines a soil's compressibility.
Abstract: Previous studies have shown that the compressibility behaviour of lime-treated organic clay with varying humic acid contents were not effective as time prolonged. Therefore, chloride salts in the amounts of 0.5%, 2.0% and 5.0% were introduced in conjunction with lime-treated organic containing 1.5% humic acid content to assess the influence of salts on the improvement of compressibility behaviour of lime-treated organic clay. The compressibility behaviour of lime-treated organic clay with varying amounts of chloride salts was studied at different curing periods. The influence of the chloride salts on the lime-clay reactions was analysed in terms of changes in void ratio (e), volumetric strain (e1), compression index (Cc), and coefficient of consolidation (cv) which defines a soil's compressibility. The addition of chloride salts to the lime-treated organic clay shows less compressible behaviour in the long term as evidenced by the oedometer tests. The results confirm the effectiveness of salt in lime-treated organic clay.
TL;DR: In this paper, a numerical study of the Mohr- Coulomb and Hardening Soil constitutive models in simulation of a braced excavation was performed and the results showed that the hardness of Mohr Coulomb soil model, a first order approximation, led to an underestimation of the diaphragm wall deflection.
Abstract: Numerical modelling continues to play a unique and intrinsic role in the process of geotechnical design. Of greatest concern are soil c onstitutive models that are employed within finite element software to predict soil behaviour. The objective o f this paper is to provide a numerical study of the Mohr- Coulomb and Hardening Soil constitutive models in simulation of a braced excavation. The Taipei Nation al Enterprise Centre (TNEC) basement construction process was well documented and the commercial finite element code, Plaxis, was selected for this numeric al comparative study. It was found that the Mohr- Coulomb soil model, a first order approximation, pr oduced an underestimation of the diaphragm wall deflection, whilst the Hardening Soil model provide d a good prediction of the observed in-situ diaphra gm wall deflections.
TL;DR: In this article, the complexities of urban cities are illustrated through many examples without naming any particular city, and the following eleven illustrative examples of some urban cities and their issues are discussed.
Abstract: Lowland problems are many. Many urban settlements are on the coastal belt, worldwide. In the past, many urban areas grew in an uncontrolled manner. The urban populations experienced increased risks, a poorer quality of life, and health problems. However, in general, there has been increasing management of many urban environments through Land use planning, building, environmental, health and safety regulations and management of emergencies, collectively balancing social, economic and environmental requirements. In this paper the complexities of urban cities are illustrated through many examples without naming any particular city. Since in modern times, globalization has created an environment where economic borders only exist. The systems are usually administered by separate authorities, which need to act together to secure sustainable urban management. Therefore actions and responses are frequently disconnected and are sometimes conflicting. To attain sustainable growth common sources of information are necessary. To emphasize the following eleven illustrative examples of some urban cities and their issues are discussed.
TL;DR: In this paper, a simple supported double steel beam was used to reproduce the behavior of structure and the free fall of the weight to the sand tank installed at the center of simply supported double-steel H beams were measured.
Abstract: Sand cushion is often utilized in rockfall protection structures as a shock absorber. Impact by rockfall is considered one of the most important variable loads for protection structures. To clarify the evaluation method and the buffering effects of impact force, the series of weight impact experiment were conducted. A simple supported double steel beam was used to reproduce the behavior of structure. Experiments were carried out by the free fall of the weight to the sand tank installed at the center of simply supported double steel H beams. The impact force of the weight and transmitted force under the sand tank as well as displacements of beam and strains of the beam were measured. Dynamic characteristics of impact force, transmitted force to the steel beam and behavior of the beam were investigated. Dynamic interaction between sand and beam, shock absorbing effect of sand and also the transfer ratio of kinetic energy of rockfall to the structure were shown.
TL;DR: In this paper, the results of a single pile test and four tests on two piles arranged in a row perpendicular to the direction of soil movement are presented, and the development of maximum bending moment, maximum shear force, and pile deflection with soil movement and the largest pile response profiles for the single pile and pile groups are compared.
Abstract: Laboratory model tests have been conducted to investigate the responses of piles subjected to lateral soil movement. The results of a single pile test and four tests on two piles arranged in a row perpendicular to the direction of soil movement are presented. The development of maximum bending moment, maximum shear force, and pile deflection with soil movement and the largest pile response profiles for the single pile and pile groups are compared. Group effect was evaluated using group factor which is defined in terms of the measured maximum bending moment. The major findings are (1) the pile head conditions (free or capped) are insignificant on piles subjected to lateral soil movement when arranged in a row, (2) the group factor decreases as the pile spacing reduces, (3) a linear relationship exists between the maximum bending moment and maximum shear force for both the pile groups and single pile.
TL;DR: In this paper, a triaxial apparatus has been developed in Geotechnical Engineering Laboratory of Kyushu University to obtain mechanical properties of unsaturated soil such as shear strength and stiffness.
Abstract: A suction controlled triaxial apparatus has been developed in Geotechnical Engineering Laboratory of Kyushu University. The apparatus has been designed to obtain mechanical properties of unsaturated soil such as shear strength and stiffness, as well as hydraulic properties of unsaturated soil, i.e. Soil Water Retention Curve (SWRC) by measuring change of drained water volume during applied matric suction. Not only for unsaturated condition, this apparatus can be also used to conduct conventional test on saturated soil. This paper focuses on the performance of the apparatus, by performing a series of multistage test on unsaturated soil under drying and wetting path. The hydraulics and mechanical properties of unsaturated soil are presented and discussed.
TL;DR: In this article, the effect of heat treatment on the mineralogy and morphology of kaolin was investigated and the results showed that there was a slight improvement in the strength of peat-kaolin mixture when the mixture was preheated to a temperature of up to 400°C.
Abstract: This paper presents an experimental work on the effect of heat treatment on the mineralogy and morphology of kaolin. Kaolin, which is moderately expansive, was preheated at temperatures ranging from 200°C to 800°C by increment of 200°C and cooled at room temperature before it was mixed with peat. Peat represents a compressible soil and has low bearing value. The main aim of the work is to study the effect of heat treatment on shear strength parameters of peat-kaolin mixture. The mixtures are prepared at different proportions, and at each proportion triaxial samples were prepared and tested in the undrained condition to study the shear strength parameters. Untreated kaolin-soil mix was also prepared to provide a comparison between the treated and untreated soil mix in terms of the shear strength behaviour. XRD and FESEM were also carried out to investigate the change in soil micro-structure due to heat treatment. The tests showed that there was a slight improvement in the strength of peat-kaolin mixture when kaolin was preheated to a temperature of up to 400°C. Finally results were discussed and conclusions were made for the preheated kaolin-peat mixture.
TL;DR: In this paper, a method to measure the strain distribution along the installed precast spun concrete pile during full-scale load test is described, which utilizes the hollow core of the spun pile without changing the physical properties e.g. stiffness.
Abstract: One of the basic parameters required for forecasting pile deformation under loads is the characteristics and profile of the shaft load transfer from the pile to the surrounding soil. This parameter can be obtained by measuring the strain distribution along the pile during full-scale pile load test. For cast-in situ bored pile, the strain measurement can be easily done by fixing the sensors to the reinforcement cage before pouring the concrete. For precast driven / jack-in piles, the application of instrumented full-scale static load tests is far more challenging than their bored pile counterparts due to significant difference in method of pile installation. Due to practical shortcoming of conventional instrumentation method instrumented full-scale static load tests are in fact rarely used in driven pile application in this region. For hollow precast spun concrete piles attempts have been made by geotechnical engineers to measure the strain distribution by installing either an instrumented reinforcement cage or instrumented pipe into the hollow core of spun piles followed by cement grout. However in this method, known as approximate method, the measured characteristics cannot be considered to represent the working piles because the presence of reinforcement/pipe and the grout would alter the stiffness of the test pile. In this paper a method to measure the strain distribution along the installed precast spun concrete pile during full-scale pile load test is described. The method utilizes the hollow core of the spun pile without changing the physical properties e.g. stiffness, of the pile. The main advantages of this method are: the measurement can be done at any location along the pile, the sensors can be retrieved and the measured characteristics are representative of those of the working piles.
TL;DR: In this article, a part of an ongoing experimental laboratory investigation was carried out for production and characterization of high strength concrete (HSC) for heightening of an existing concrete dam in the middle of Sudan.
Abstract: This paper presents a part of an ongoing experimental laboratory investigation being carried out for production and characterization of high strength concrete (HSC) for heightening of an existing concrete dam in the middle of Sudan. Brief description of the main features of the dam and concrete works is presented. Hundreds of trial mixes were performed and tested using local Sudanese aggregates with addition of mineral admixtures (Silica Fume and Fly Ash) and Super plasticizers. Six grades of HSC (50, 60, 70, 80, 90, 100 MPa) had been success fully produced and their mechanical properties were measured and documented. Statistical analysis of tests results was performed and simple correlations were developed relating compressive strength to flexural and Splitting Strengths. The results have offered an important insight for optimizing the rheological characteristics of HSC and permitted to develop guidelines for optimum mix design methods for HSC from locally available aggregates in Sudan. The effect of w/c ratio on strength of HSC was also highlighted. It is concluded that local concrete materials, in combination with mineral admixtures can be utilized in producing High Strength Concrete in Sudan.
TL;DR: In this paper, the authors quantify the impact of these parameters as well as the percentage of fines on the mechanical behaviour of the mixed material and predict the strength of mixed material after seven and 28 days of curing.
Abstract: Deep mixing is a method frequently used for various applications ranging from ground improvement and confinement to foundations With the increase of the use of deep mixing for foundations, it is imperative to better define the mechanical behaviour and ageing of the material, which depends on the cement content and grain size distribution This study aims to quantify the impact of these parameters as well as the percentage of fines on the mechanical behaviour of the mixed material A number of unconfined compression tests were carried out The results showed that it was possible to predict the strength of the mixed material after seven and 28 days of curing, based on the cement content and the percentage of fines
TL;DR: Ion Chromatography and Flow Injection Analysis systems were integrated by a switching valve as discussed by the authors, and a sampling kit was designed by disposable syringe, 0.45um syringe filter, and 2mL plastic vial.
Abstract: Ion Chromatography and Flow Injection Analysis systems were integrated by a switching valve. Then, sampling kit was designed by disposable syringe, 0.45um syringe filter, and 2mL plastic vial. 13 water samples were collected from oxidation pond and natural stream in a University campus. Four analytical modes were applied for standard solutions and the environmental samples. The detection limit (S/N =3) in µM/L were as follows, SO4 2- (0.31), Cl - (0.50), NO3 - (0.89), Na + (0.52), NH4 + (0.94), K + (1.24), Mg 2+ (0.76), Ca 2+ (1.75), NO2 - (0.02), and PO4 3- (0.12), and its EC was 0.03 µS/cm. Our analytical approach was simple, rapid, low-cost, and multi-parameter that was satisfactory to assess the water samples. Due to the sampling, transportation, storage processes are drastically improved, our approach has potential to contribute to strategic environmental assessment.
TL;DR: In this article, a study was carried out for an area where several centimeters wide ground cracks extending over more than one kilometer distance across a populated area in Saudi Arabia in the northern and central part of Saudi Arabia showed frequent near surface cracks and distress at several sites.
Abstract: A semi-arid shale formation in the northern and central part of Saudi Arabia showed frequent near surface cracks and distress at several sites. This phenomenon was found to be of a serious risk to structures founded on or near cracks or failure zones. This study was carried out for an area where several centimeters wide ground cracks extending over more than one kilometer distance across a populated area in Saudi Arabia. The dominant subsurface formation in the area is reddish brown stiff to hard silty to clayey shale underlain by sandstone formation. The subsurface material was explored and clayey shale samples were extracted. The study included borehole drilling and test pit excavations. Soil classification and consistency tests were performed. A series of physical and chemical testing confirmed the expansive nature of the shale. The possible causes of cracks and the mechanisms of failure in semi-arid shale were covered and discussed in sufficient details. Engineering guides for buildings and construction in typical zones were presented.
TL;DR: In this article, four physical models are designed to investigate the flow patterns for silos discharge behavior with double openings, and the results from discrete element analysis can match well with the experimental study if suitable micro-parameters are used in the analysis.
Abstract: Silo container is a very important storage structure for coal, sand and other granular materials. Nonhomogeneous granular flow is sometimes found in ore discharging in mining engineering, but so far there are only limited studies to this topic, particularly for double opening silo. In views of that, it is necessary to figure out the details about the flow pattern behavior. In the present paper, four physical models are designed to investigate the flow patterns for silos discharge behavior with double openings. The opening spacing, height ratio, sand properties and automatic separated manners are considered in these laboratory tests. Meanwhile, twodimensional discrete element method is used to reproduce the flow behavior as well as to evaluate the dynamic wall stresses distribution on the silo hopper from bottom to top. It is found that the flow pattern is very sensitive to the spacing between openings under close opening silos. For the wide opening silos, the discharge efficiency would change nearly 30%. The arch effect in the dead zone and ore recovery are significantly influenced by the height /spacing ratio. The results from discrete element analysis can match well with the experimental study if suitable micro-parameters are used in the analysis.