Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 180

Search results for: Sandy Van Vuuren

180 Effect of Base Coarse Layer on Load-Settlement Characteristics of Sandy Subgrade Using Plate Load Test

Authors: R. Ziaie Moayed, A. Nazeri, H. Ghiasinejad

Abstract:

The present research has been performed to investigate the effect of base course application on load-settlement characteristics of sandy subgrade using plate load test. The main parameter investigated in this study was the subgrade reaction coefficient. The model tests were conducted in a 1.35 m long, 1 m wide, and 1 m deep steel test box of Imam Khomeini International University (IKIU Calibration Chamber). The base courses used in this research were in three different thicknesses of 15 cm, 20 cm, and 30 cm. The test results indicated that in the case of using base course over loose sandy subgrade, the values of subgrade reaction coefficient can be increased from 7  to 132 , 224 , and 396  in presence of 15 cm, 20 cm, and 30 cm base course, respectively.

Keywords: plate load test, modulus of subgrade reaction, base course, sandy subgrade

Procedia PDF Downloads 85
179 Evaluation of Shear Strength Parameters of Rudsar Sandy Soil Stabilized with Waste Rubber Chips

Authors: R. Ziaie Moayed, M. Hamidzadeh

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The use of waste rubber chips not only can be of great importance in terms of the environment, but also can be used to increase the shear strength of soils. The purpose of this study was to evaluate the variation of the internal friction angle of liquefiable sandy soil using waste rubber chips. For this purpose, the geotechnical properties of unmodified and modified soil samples by waste lining rubber chips have been evaluated and analyzed by performing the triaxial consolidated drained test. In order to prepare the laboratory specimens, the sandy soil in part of Rudsar shores in Gilan province, north of Iran with high liquefaction potential has been replaced by two percent of waste rubber chips. Samples have been compressed until reaching the two levels of density of 15.5 and 16.7 kN/m3. Also, in order to find the optimal length of chips in sandy soil, the rectangular rubber chips with the widths of 0.5 and 1 cm and the lengths of 0.5, 1, and 2 cm were used. The results showed that the addition of rubber chips to liquefiable sandy soil greatly increases the shear resistance of these soils. Also, it can be seen that decreasing the width and increasing the length-to-width ratio of rubber chips has a direct impact on the shear strength of the modified soil samples with rubber chips.

Keywords: Improvement, Shear Strength, sandy soil, internal friction angle, rubber chip

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178 Effect of Oil Contamination on the Liquefaction Behavior of Sandy Soils

Authors: Seyed Abolhasan Naeini, Mohammad Mahdi Shojaedin

Abstract:

Oil leakage from the pipelines and the tanks carrying them, or during oil extraction, could lead to the changes in the characteristics and properties of the soil. In this paper, conducting a series of experimental cyclic triaxial tests, the effects of oil contamination on the liquefaction potential of sandy soils is investigated. The studied specimens are prepared by mixing the Firoozkuh sand with crude oil in 4, 8 and 12 percent by soil dry weight. The results show that the oil contamination up to 8% causes an increase in the soil liquefaction resistance and then with increase in the contamination, the liquefaction resistance decreases.

Keywords: oil contamination, liquefaction resistance, cyclic triaxial test, sandy soil

Procedia PDF Downloads 364
177 The Grain Size Distribution of Sandy Soils in Libya

Authors: Massoud Farag Abouklaish

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The main aim of the present study is to investigate and classify the particle size distribution of sandy soils in Libya. More than fifty soil samples collected from many regions in North, West and South of Libya. Laboratory sieve analysis tests performed on disturbed soil samples to determine grain size distribution. As well as to provide an indicator of general engineering behavior and good understanding, test results are presented and analysed. In addition, conclusions, recommendations are made.

Keywords: Libya, grain size, sandy soils, sieve analysis tests

Procedia PDF Downloads 432
176 Ichnofacies and Microfacies Analysis of Late Eocene Rocks in Fayum Area, Egypt and Their Paleoenvironmental Implications

Authors: Dina Sayed, Soheir El-Shazly, Yasser Salama, Gouda Abdelgawad

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Abstract- The Late Eocene rocks (Qasr El-Sagha ) Formation, north east of Birket Qarun in Fayum area of Egypt reveals 6 Ichnogenera Thalassinoides Ehrenberg, 1944, Ophiomorpha Lundgren (1891), Skolithos Haldemann (1840), Diplocraterion Torell, 1870, Arenicolites Salter, 1857 and Planolites Nicholson, 1873. These Ichnogenera are related to Skolithos ichnofacies of typical sandy shoreline environment, only the ichnogenus Planolites is related to Cruziana ichnofacies, which occurs in somewhat deeper water than the Skolithos ichnofacies. Four microfacies types have been distinguished from the study sections, Mudstone, Sandy micrite (wackstone), Sandy dolomitic ferruginous biomicrite (Packstone), Sandy glauconitic biomicrite (packstone). The ichnofacies and the microfacies study indicates that the study area was deposited in shelf lagoon with open circulation environment

Keywords: Egypt, microfacies, Fayum, icnofacies, late eocene

Procedia PDF Downloads 86
175 Magnesium Foliar Application and Phosphorien Soil Inoculation Positively Affect Pisum sativum L. Plants Grown on Sandy Calcareous Soil

Authors: Saad M. Howladar, Mostafa M. Rady, Ashraf Sh. Osman, Hassan S. Al-Zahrani

Abstract:

The effects of soil inoculation with phosphorien-containing Phosphate-Dissolving Bacteria (PDB) and/or magnesium (Mg) foliar application at the rates of 0, 0.5 and 1mM on growth, green pod and seed yields, and chemical constituents of Pisum sativum L. grown on a sandy calcareous soil were investigated. Results indicated that PDB and/or Mg significantly increased shoot length, number of branches plant–1, total leaf area plant–1 and canopy dry weight plant–1, leaf contents of pigments, soluble sugars, free proline, nitrogen, phosphorus, potassium, magnesium, and calcium, and Ca/Na ratio, while leaf Na content was reduced. PDB and/or Mg also increased green pod and seed yields. We concluded that PDB and Mg have pronounced positive effects on Pisum sativum L. plants grown on sandy calcareous soil. PDB and Mg, therefore, have the potential to be applied for various crops to overcome the adverse effects of the newly-reclaimed sandy calcareous soils.

Keywords: bio-p-fertilizer, mg foliar application, newly-reclaimed soils, Pisum sativum L

Procedia PDF Downloads 238
174 Ethnobotany and Antimicrobial Effects of Medicinal Plants Used for the Treatment of Sexually Transmitted Infections in Lesotho

Authors: Sandy Van Vuuren, Lerato Kose, Annah Moteetee

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Lesotho, a country surrounded by South Africa has one of the highest rates of sexually transmitted infections (STI’s) in the world. In fact, the country ranks third highest with respect to infections related to the human immunodeficiency virus (HIV). Despite the high prevalence of STI’s, treatment has been a challenge due to limited accessibility to health facilities. An estimated 77% of the population lives in rural areas and more than 60% of the country is mountainous. Therefore, many villages remain accessible only by foot or horse-back. Thus, the Basotho (indigenous people from Lesotho) have a rich cultural heritage of plant use. The aim of this study was to determine what plant species are used for the treatment of STI’s and which of these have in vitro efficacy against pathogens such as Candida albicans, Gardnerella vaginalis, Oligella ureolytica, and Neisseria gonorrhoeae. A total of 34 medicinal plants were reported by traditional practitioners for the treatment of STI’s. Sixty extracts, both aqueous and organic (mixture of methanol and dichloromethane), from 24 of the recorded plant species were assessed for antimicrobial activity using the minimum inhibition concentration (MIC) micro-titre plate dilution assay. Neisseria gonorrhoeae (ATCC 19424) was found to be the most susceptible among the test pathogens, with the majority of the extracts (21) displaying noteworthy activity (MIC values ≤ 1 mg/ml). Helichrysum caespititium was found to be the most antimicrobially active species (MIC value of 0.01 mg/ml). The results of this study support, to some extent, the traditional medicinal uses of the evaluated plants for the treatment of STI’s, particularly infections related to gonorrhoea.

Keywords: Africa, Candida albicans, Neisseria gonorrhoeae, Gardnerella vaginalis, Oligella urealytica

Procedia PDF Downloads 80
173 Effect of Plastic Fines on Undrained Behavior of Clayey Sands

Authors: Saeed Talamkhani, Seyed Abolhassan Naeini

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In recent years, the occurrence of several liquefactions in sandy soils containing various values of clay content has shown that in addition to silty sands, clayey sands are also susceptible to liquefaction. Therefore, it is necessary to investigate the properties of these soil compositions and their behavioral characteristics. This paper presents the effect of clay fines on the undrained shear strength of sands at various confining pressures. For this purpose, a series of unconsolidated undrained triaxial shear tests were carried out on clean sand and sand mixed with 5, 10, 15, 20, and 30 percent of clay fines. It was found that the presence of clay particle in sandy specimens change the dilative behavior to contraction. The result also showed that increasing the clay fines up to 10 percent causes to increase the potential for liquefaction, and decreases it at higher values fine content. These results reveal the important role of clay particles in changing the undrained strength of the sandy soil.

Keywords: Liquefaction, triaxial test, clayey sand, undrained shear strength

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172 Effects of Organic Amendments on Primary Nutrients (N, P and K) in a Sandy Soil

Authors: Nejib Turki, Karima Kouki Khalfallah

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The effect of six treatments of organic amendments were evaluated on a sandy soil in the region of Soukra in Tunisia. T1: cattle manure 55 t.ha-1, T2: commercial compost from Germany to 1 t.ha-1, T3: a mixture of 27.5 t.ha-1 of T1 with 0.5 t. ha-1 of T2, T4: commercial compost from France 2 t.ha-1, T5: a Tunisian commercial compost to 10 t.ha-1 and T0: control without treatment. The nitrogen in the soil increase to 0.029 g.kg-1 of soil treatment for the T1 and 0.021 g. kg-1 of soil treatment for the T3. The highest content of P2O5 has been registered by the T3 treatment that 0.44 g kg-1 soil with respect to the control (T0), which shows a content of 0.36 g.kg-1 soil. The soil was initially characterized by a potassium content of 0.8 g kg-1 soil, K2O exchangeable rate varied between 0.63 g.Kg-1 and 0.71 g.kg-1 soil respectively T2 and T1.

Keywords: compost, organic amendement, Ntot, P2O5, K2O

Procedia PDF Downloads 474
171 Minimization of Seepage in Sandy Soil Using Different Grouting Types

Authors: A. Ibrahim, Eng. M. Ahmed, M. Ashour

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One of the major concerns facing dam is the repair of their structures to prevent the seepage under them. In previous years, many existing dams have been treated by grouting, but with varying degrees of success. One of the major reasons for this erratic performance is the unsuitable selection of the grouting materials to reduce the seepage. Grouting is an effective way to improve the engineering properties of the soil and strengthen of the permeability of the soil to reduce the seepage. The purpose of this paper is to focus on the efficiency of current available grouting materials and techniques from construction, environmental and economical point of view. The seepage reduction usually accomplished by either chemical grouting or cementious grouting using ultrafine cement. In addition, the study shows a comparison between grouting materials according to their degree of permeability reduction and cost. The application of seepage reduction is based on the permeation grouting using grout curtain installation. The computer program (SEEP/W) is employed to model a dam rested on sandy soil, using grout curtain to reduce seepage quantity and hydraulic gradient by different grouting materials. This study presents a relationship that takes into account the permeability of the soil, grout curtain spacing and a new performance parameter that can be used to predict the best selection of grouting materials for seepage reduction.

Keywords: Permeability, sandy soil, seepage, grouting

Procedia PDF Downloads 200
170 Poultry Manure and Its Derived Biochar as a Soil Amendment for Newly Reclaimed Sandy Soils under Arid and Semi-Arid Conditions

Authors: W. S. Mohamed, A. A. Hammam

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Sandy soils under arid and semi-arid conditions are characterized by poor physical and biochemical properties such as low water retention, rapid organic matter decomposition, low nutrients use efficiency, and limited crop productivity. Addition of organic amendments is crucial to develop soil properties and consequently enhance nutrients use efficiency and lessen organic carbon decomposition. Two years field experiments were developed to investigate the feasibility of using poultry manure and its derived biochar integrated with different levels of N fertilizer as a soil amendment for newly reclaimed sandy soils in Western Desert of El-Minia Governorate, Egypt. Results of this research revealed that poultry manure and its derived biochar addition induced pronounced effects on soil moisture content at saturation point, field capacity (FC) and consequently available water. Data showed that application of poultry manure (PM) or PM-derived biochar (PMB) in combination with inorganic N levels had caused significant changes on a range of the investigated sandy soil biochemical properties including pH, EC, mineral N, dissolved organic carbon (DOC), dissolved organic N (DON) and quotient DOC/DON. Overall, the impact of PMB on soil physical properties was detected to be superior than the impact of PM, regardless the inorganic N levels. In addition, the obtained results showed that PM and PM application had the capacity to stimulate vigorous growth, nutritional status, production levels of wheat and sorghum, and to increase soil organic matter content and N uptake and recovery compared to control. By contrast, comparing between PM and PMB at different levels of inorganic N, the obtained results showed higher relative increases in both grain and straw yields of wheat in plots treated with PM than in those treated with PMB. The interesting feature of this research is that the biochar derived from PM increased treated sandy soil organic carbon (SOC) 1.75 times more than soil treated with PM itself at the end of cropping seasons albeit double-applied amount of PM. This was attributed to the higher carbon stability of biochar treated sandy soils increasing soil persistence for carbon decomposition in comparison with PM labile carbon. It could be concluded that organic manures applied to sandy soils under arid and semi-arid conditions are subjected to high decomposition and mineralization rates through crop seasons. Biochar derived from organic wastes considers as a source of stable carbon and could be very hopeful choice for substituting easily decomposable organic manures under arid conditions. Therefore, sustainable agriculture and productivity in newly reclaimed sandy soils desire one high rate addition of biochar derived from organic manures instead of frequent addition of such organic amendments.

Keywords: Biochar, Poultry, sandy soil, dissolved organic carbon, N-uptake

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169 Shoreline Change Estimation from Survey Image Coordinates and Neural Network Approximation

Authors: Tienfuan Kerh, Hsienchang Lu, Rob Saunders

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Shoreline erosion problems caused by global warming and sea level rising may result in losing of land areas, so it should be examined regularly to reduce possible negative impacts. Initially in this study, three sets of survey images obtained from the years of 1990, 2001, and 2010, respectively, are digitalized by using graphical software to establish the spatial coordinates of six major beaches around the island of Taiwan. Then, by overlaying the known multi-period images, the change of shoreline can be observed from their distribution of coordinates. In addition, the neural network approximation is used to develop a model for predicting shoreline variation in the years of 2015 and 2020. The comparison results show that there is no significant change of total sandy area for all beaches in the three different periods. However, the prediction results show that two beaches may exhibit an increasing of total sandy areas under a statistical 95% confidence interval. The proposed method adopted in this study may be applicable to other shorelines of interest around the world.

Keywords: digitalized shoreline coordinates, survey image overlaying, neural network approximation, total beach sandy areas

Procedia PDF Downloads 148
168 Integrated Geotechnical and Geophysical Investigation of a Proposed Construction Site at Mowe, Southwestern Nigeria

Authors: Kayode Festus Oyedele, Sunday Oladele, Adaora Chibundu Nduka

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The subsurface of a proposed site for building development in Mowe, Nigeria, using Standard Penetration Test (SPT) and Cone Penetrometer Test (CPT) supplemented with Horizontal Electrical Profiling (HEP) was investigated with the aim of evaluating the suitability of the strata for foundation materials. Four SPT and CPT were implemented using 10 tonnes hammer. HEP utilizing Wenner array were performed with inter-electrode spacing of 10 – 60 m along four traverses coincident with each of the SPT and CPT. The HEP data were processed using DIPRO software and textural filtering of the resulting resistivity sections was implemented to enable delineation of hidden layers. Sandy lateritic clay, silty lateritic clay, clay, clayey sand and sand horizons were delineated. The SPT “N” value defined very soft to soft sandy lateritic (<4), stiff silty lateritic clay (7 – 12), very stiff silty clay (12 - 15), clayey sand (15- 20) and sand (27 – 37). Sandy lateritic clay (5-40 kg/cm2) and silty lateritic clay (25 - 65 kg/cm2) were defined from the CPT response. Sandy lateritic clay (220-750 Ωm), clay (< 50 Ωm) and sand (415-5359 Ωm) were delineated from the resistivity sections with two thin layers of silty lateritic clay and clayey sand defined in the texturally filtered resistivity sections. This study concluded that the presence of incompetent thick clayey materials (18 m) beneath the study area makes it unsuitable for shallow foundation. Deep foundation involving piling through the clayey layers to the competent sand at 20 m depth was recommended.

Keywords: Standard Penetration Test, foundation, cone penetrometer, lithologic texture, resistivity section

Procedia PDF Downloads 111
167 Sensitivity Analysis of Movable Bed Roughness Formula in Sandy Rivers

Authors: Mehdi Fuladipanah

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Sensitivity analysis as a technique is applied to determine influential input factors on model output. Variance-based sensitivity analysis method has more application compared to other methods because of including linear and non-linear models. In this paper, van Rijn’s movable bed roughness formula was selected to evaluate because of its reasonable results in sandy rivers. This equation contains four variables as: flow depth, sediment size,bBed form height and bed form length. These variable’s importance was determined using the first order of Fourier Amplitude Sensitivity Test. Sensitivity index was applied to evaluate importance of factors. The first order FAST based sensitivity indices test, explain 90% of the total variance that is indicating acceptance criteria of FAST application. More value of this index is indicating more important variable. Results show that bed form height, bed form length, sediment size and flow depth are more influential factors with sensitivity index: 32%, 24%, 19% and 15% respectively.

Keywords: variance, sdensitivity analysis, movable bed roughness formula, Sandy River

Procedia PDF Downloads 131
166 Using Biopolymer Materials to Enhance Sandy Soil Behavior

Authors: Abdelazim Negm, Mohamed Ayeldeen

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Nowadays, strength characteristics of soils have more importance due to increasing building loads. In some projects, geotechnical properties of the soils are be improved using man-made materials varying from cement-based to chemical-based. These materials have proven successful in improving the engineering properties of the soil such as shear strength, compressibility, permeability, bearing capacity etc.. However, the use of these artificial injection formulas often modifies the pH level of soil, contaminates soil and groundwater. This is attributed to their toxic and hazardous characteristics. Recently, an environmentally friendly soil treatment method or Biological Treatment Method (BTM) was to bond particles of loose sandy soils. This research paper presents the preliminary results of using biopolymers for strengthening cohesionless soil. Xanthan gum was identified for further study over a range of concentrations varying from 0.25% to 2.00%. Xanthan gum is a polysaccharide secreted by the bacterium Xanthomonas campestris, used as a food additive and it is a nontoxic material. A series of direct shear, unconfined compressive strength, and permeability tests were carried out to investigate the behavior of sandy soil treated with Xanthan gum with different concentration ratios and at different curing times. Laser microscopy imaging was also conducted to study the microstructure of the treated sand. Experimental results demonstrated the compatibility of Xanthan gum to improve the geotechnical properties of sandy soil. Depending on the biopolymer concentration, it was observed that the biopolymers effectively increased the cohesion intercept and stiffness of the treated sand and reduced the permeability of sand. The microscopy imaging indicates that the cross-links of the biopolymers through and over the soil particles increase with the increase of the biopolymer concentration.

Keywords: Sand, Permeability, Shear Strength, biopolymer, direct shear, xanthan gum

Procedia PDF Downloads 119
165 Enhancement of the Corrosion Resistance of Fastening System of Ballasted ‎Railway in Sandy Desert by Using Nano Coating

Authors: Milad Alizadeh Galdiani, Mohamad Ali Mohit, Navid Sabet, Fatemeh Palizdar

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Railway as one of the most important transportation modes, passes through ‎various areas with different conditions ‎inevitably, and in many countries such as ‎China, United States, Australia, and Iran, it passes through sandy ‎desert areas. One ‎of the main problems in these areas is the movement of sand, causing various ‎damages ‎to ballasted railway track such as corrosion in the railway fastening system. ‎The soil composition of some desert areas like Fahraj in Iran consists of sand ‎and ‎salt. Due to the movement of sand and corrosive ions of salt, the fastening system ‎of the railway is ‎corroded, which, in turn, reduces the thickness of the components ‎and their life span.‎ In this research, the Nano-coating for fastening system of ‎the railway is ‎introduced, and its performance has been investigated in both ‎laboratory and field tests. The Nano-coating of ‎the fastening system consists of zinc-rich, epoxy, polyurethane, and additive, which is produced through ‎Nano ‎technology. This layer covers the surface of the fastening system and ‎prohibits the chemical reactions, which result in ‎corrosion. The results of ‎Electrochemical Impedance Spectroscopy (EIS) ‎indicate that corrosion resistance ‎increases 315 times by using nano-coating, salt spray test results demonstrate that ‎nano-coated components remained intact after 1000 hours.‎

Keywords: ballasted railway, Nano-coating, railway fastening system, sandy desert

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164 Development of In Situ Permeability Test Using Constant Discharge Method for Sandy Soils

Authors: A. Rifa’i, Y. Takeshita, M. Komatsu

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The post-rain puddles problem that occurs in the first yard of Prambanan Temple are often disturbing visitor activity. A poodle layer and a drainage system has ever built to avoid such a problem, but puddles still didn’t stop appearing after rain. Permeability parameter needs to be determined by using more simple procedure to find exact method of solution. The instrument modelling were proposed according to the development of field permeability testing instrument. This experiment used proposed Constant Discharge method. Constant Discharge method used a tube poured with constant water flow. The procedure were carried out from unsaturated until saturated soil condition. Volumetric water content (θ) were being monitored by soil moisture measurement device. The results were relationship between k and θ which drawn by numerical approach Van Genutchen model. Parameters θr optimum value obtained from the test was at very dry soil. Coefficient of permeability with a density of 19.8 kN/m3 for unsaturated conditions was in range of 3 x 10-6 cm/sec (Sr= 68 %) until 9.98 x 10-4 cm/sec (Sr= 82 %). The equipment and testing procedure developed in this research was quite effective, simple and easy to be implemented on determining field soil permeability coefficient value of sandy soil. Using constant discharge method in proposed permeability test, value of permeability coefficient under unsaturated condition can be obtained without establish soil water characteristic curve.

Keywords: sandy soil, constant discharge method, in situ permeability test, unsaturated conditions

Procedia PDF Downloads 251
163 Soil Quality Response to Long-Term Intensive Resources Management and Soil Texture

Authors: Kristina Amaleviciute, Jonas Volungevicius, Dalia Feiziene, Virginijus Feiza, Agne Putramentaite, Sarunas Antanaitis

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The investigations on soil conservation are one of the most important topics in modern agronomy. Soil management practices have great influence on soil physico-chemical quality and GHG emission. Research objective: To reveal the sensitivity and vitality of soils with different texture to long-term antropogenisation on Cambisol in Central Lithuania and to compare them with not antropogenised soil resources. Methods: Two long-term field experiments (loam on loam; sandy loam on loam) with different management intensity were estimated. Disturbed and undisturbed soil samples were collected from 5-10, 15-20 and 30-35 cm depths. Soil available P and K contents were determined by ammonium lactate extraction, total N by the dry combustion method, SOC content by Tyurin titrimetric (classical) method, texture by pipette method. In undisturbed core samples soil pore volume distribution, plant available water (PAW) content were determined. A closed chamber method was applied to quantify soil respiration (SR). Results: Long-term resources management changed soil quality. In soil with loam texture, within 0-10, 10-20 and 30-35 cm soil layers, significantly higher PAW, SOC and mesoporosity (MsP) were under no-tillage (NT) than under conventional tillage (CT). However, total porosity (TP) under NT was significantly higher only in 0-10 cm layer. MsP acted as dominant factor for N, P and K accumulation in adequate layers. P content in all soil layers was higher under NT than in CT. N and K contents were significantly higher than under CT only in 0-10 cm layer. In soil with sandy loam texture, significant increase in SOC, PAW, MsP, N, P and K under NT was only in 0-10 cm layer. TP under NT was significantly lower in all layers. PAW acted as strong dominant factor for N, P, K accumulation. The higher PAW the higher NPK contents were determined. NT did not secure chemical quality within deeper layers than CT. Long-term application of mineral fertilisers significantly increased SOC and soil NPK contents primarily in top-soil. Enlarged fertilization determined the significantly higher leaching of nutrients to deeper soil layers (CT) and increased hazards of top-soil pollution. Straw returning significantly increased SOC and NPK accumulation in top-soil. The SR on sandy loam was significantly higher than on loam. At dry weather conditions, on loam SR was higher in NT than in CT, on sandy loam SR was higher in CT than in NT. NPK fertilizers promoted significantly higher SR in both dry and wet year, but suppressed SR on sandy loam during usual year. Not antropogenised soil had similar SOC and NPK distribution within 0-35 cm layer and depended on genesis of soil profile horizons.

Keywords: Fertilizers, Soil Tillage, soil texture, straw, long-term experiments

Procedia PDF Downloads 160
162 The Interactions between Phosphorus Leaching and Lime Application in Undisturbed Soil Columns with Different Soil Textures

Authors: Faezeh Eslamian, Zhiming Qi, Michael J. Tate

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Phosphorus losses from agricultural fields through leaching is one of the main contributors to eutrophication of lakes in Quebec as well as North America. The main objective of this study is to evaluate the application of high calcium hydrated lime as a soil amendment in reducing the subsurface transport of phosphorus to water bodies by studying the interactions between phosphorus leaching and lime application in three common agricultural soil textures (sandy loam, loam and clay loam) in Quebec. For this purpose, 6 intact soil columns of 10 cm diameter and 20 cm deep were taken from each of the three different soil textured agricultural fields. Lime (high calcium hydrated lime) was applied to the top 5 cm of half of the intact soil columns while the rest were left as controls. The columns were leached with artificial rainwater in-consecutively at a rate of 3 mm h-1 over a 90-day period. The total amount of water added was equal to the average total rainfall of the region in fall. The leachate samples were collected daily and analyzed for dissolved reactive phosphorus, total dissolved phosphorus, total phosphorus, pH, electrical conductivity, calcium, magnesium, potassium and iron. The results showed that lime was able to significantly reduce dissolved reactive phosphorus concentrations in the leachates by 70 and 40 percent in sandy loam and loam soil columns, respectively, while phosphorus concentration in the clay loam soil leachates were increased by 40 percent. The calcium in lime has P-binding capabilities. Soil chemical properties in sandy and loamy soils can affect phosphorus leaching, whereas, transport mechanisms in clay soils with macropores dominate phosphorus leaching behaviors. The presence of preferential pathways and cracks in the clay soil columns has led to a quick transport of phosphorus through the soil and the less contact time with the soil matrix, therefore, causing less opportunity for P sorption and larger P release. Application of lime to agricultural fields can be considered as a promising measure in mitigating phosphorus loss from sandy loam and loam soils.

Keywords: Leaching, lime, Phosphorus, soil texture

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161 Electroremediation of Saturated and Unsaturated Nickel-Contaminated Soils

Authors: Waddah Abdullah, Saleh Al-Sarem

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Electrokinetic remediation was undoubtedly proven to be one of the most efficient techniques used to clean up soils contaminated with polar charged contaminants (such as heavy metals) and non-polar organic contaminants. It can be efficiently used to clean up low permeability mud, wastewater, electroplating wastes, sludge, and marine dredging. This study presented and discussed the results of electrokinetic remediation processes to clean up soils contaminated with nickel. Two types of electrokinetics cells were used: an open cell and an advanced cylindrical cell. Two types of soils were used for this investigation; the Azraq green clay which has very low permeability taken from the eastern part of Jordan (city of Azraq) and a sandy soil having, relatively, very high permeability. The clayey soil was spiked with 500 ppm of nickel, and the sandy soil was spiked with 1500 ppm of nickel. Fully saturated and partially saturated clayey soils were used for the clean-up process. Clayey soils were tested under a direct current of 80 mA and 50 mA to study the effect of the electrical current on the remediation process. Chelating agent (Na-EDTA), disodium ethylene diamine tetraacetatic acid, was used in both types of soils to enhance the electroremediation process. The effect of carbonates presence in the contaminated soils, also, was investigated by use of sodium carbonate and calcium carbonate. pH changes in the anode and the cathode compartments were controlled by use of buffer solutions. The results of the investigation showed that for the fully saturated clayey soil spiked with nickel had an average removal efficiency of 64%, and the average removal efficiency was 46% for the unsaturated clayey soil. For the sandy soil, the average removal efficiency of Nickel was 90%. Test results showed that presence of carbonates in the remediated soils retarded the clean-up process of nickel-contaminated soils (removal efficiency was reduced from 90% to 60%). EDTA enhanced decontamination of nickel contaminated clayey and sandy soils with carbonates was studied. The average removal efficiency increased from 60% (prior to using EDTA) to more than 90% after using EDTA.

Keywords: Electroremediation, EDTA, buffer solution, nickel removal efficiency

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160 Plane of Equal Settlement above HDD’s Borehole before Operational Condition

Authors: Shokoufeh Sadeghifard

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This study is a review of the nature of soil arching that develops in the upper layer of soil during drilling processes before pulling product pipe inside the hole. This study is based on the results of some parametric studies which are investigating the behavior of drained sandy soil above HDD borehole using Plaxis finite element solution. The influence of drilling mud injection in these series of analyses has been ignored. However, a suitable drilling mud pressure helps to achieve stable arch when the height of soil cover over the drilling borehole is not enough. In this study, the soil response to the formation of a HDD borehole is compared to arching theory developed by Terzaghi (1943). It is found that Terzaghi’s approach is capable of describing all of the behaviour seen when a stable arch forms. According to the numerical results, a suitable safe depth of 4D, D is borehole diameter, is suggested for typical range of HDD borehole in sandy soil.

Keywords: Settlement, Drilling, plaxis, finite element, HDD, arching

Procedia PDF Downloads 238
159 Effect of Fines on Liquefaction Susceptibility of Sandy Soil

Authors: Amin Chegenizadeh, Hamid Nikraz, Ayad Salih Sabbar

Abstract:

Investigation of liquefaction susceptibility of materials that have been used in embankments, slopes, dams, and foundations is very essential. Many catastrophic geo-hazards such as flow slides, declination of foundations, and damage to earth structure are associated with static liquefaction that may occur during abrupt shearing of these materials. Many artificial backfill materials are mixtures of sand with fines and other composition. In order to provide some clarifications and evaluations on the role of fines in static liquefaction behaviour of sand sandy soils, the effect of fines on the liquefaction susceptibility of sand was experimentally examined in the present work over a range of fines content, relative density, and initial confining pressure. The results of an experimental study on various sand-fines mixtures are presented. Undrained static triaxial compression tests were conducted on saturated Perth sand containing 5% bentonite at three different relative densities (10, 50, and 90%), and saturated Perth sand containing both 5% bentonite and slag (2%, 4%, and 6%) at single relative density 10%. Undrained static triaxial tests were performed at three different initial confining pressures (100, 150, and 200 kPa). The brittleness index was used to quantify the liquefaction potential of sand-bentonite-slag mixtures. The results demonstrated that the liquefaction susceptibility of sand-5% bentonite mixture was more than liquefaction susceptibility of clean sandy soil. However, liquefaction potential decreased when both of two fines (bentonite and slag) were used. Liquefaction susceptibility of all mixtures decreased with increasing relative density and initial confining pressure.  

Keywords: slag, Liquefaction, bentonite, brittleness index

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158 Oily Sludge Bioremediation Pilot Plant Project, Nigeria

Authors: Ime R. Udotong, Ofonime U. M. John, Justina I. R. Udotong

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Brass terminal, one of the several crude oil and petroleum products storage/handling facilities in the Niger Delta was built in the 1980s. Activities at this site, over the years, released crude oil into this 3 m-deep, 1500 m-long canal lying adjacent to the terminal with oil floating on it and its sediment heavily polluted. To ensure effective clean-up, three major activities were planned: Site characterization, bioremediation pilot plant construction and testing and full-scale bioremediation of contaminated sediment/bank soil by land farming. The canal was delineated into 12 lots and each characterized, with reference to the floating oily phase, contaminated sediment and canal bank soil. As a result of site characterization, a pilot plant for on-site bioremediation was designed and a treatment basin constructed for carrying out pilot bioremediation test. Following a designed sampling protocol, samples from this pilot plant were collected for analysis at two laboratories as a quality assurance/quality control check. Results showed that Brass Canal upstream is contaminated with dark, thick and viscous oily film with characteristic hydrocarbon smell while downstream, thin oily film interspersed with water were observed. Sediments were observed to be dark with mixture of brownish sandy soil with TPH ranging from 17,800 mg/kg in Lot 1 to 88,500 mg/kg in Lot 12 samples. Brass Canal bank soil was observed to be sandy from ground surface to 3m, below ground surface (bgs) it was silty-sandy and brownish while subsurface soil (4-10m bgs) was sandy-clayey and whitish/grayish with typical hydrocarbon smell. Preliminary results obtained so far have been very promising but were proprietary. This project is considered, to the best of technical literature knowledge, the first large-scale on-site bioremediation project in the Niger Delta region, Nigeria.

Keywords: Bioremediation, contaminated sediment, land farming, oily sludge, oil terminal

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157 Seismic Soil-Pile Interaction Considering Nonlinear Soil Column Behavior in Saturated and Dry Soil Conditions

Authors: Mohammad Moeini, Mehrdad Ghyabi, Kiarash Mohtasham Dolatshahi

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This paper investigates seismic soil-pile interaction using the Beam on Nonlinear Winkler Foundation (BNWF) approach. Three soil types are considered to cover all the possible responses, as well as nonlinear site response analysis using finite element method in OpenSees platform. Excitations at each elevation that are output of the site response analysis are used as the input excitation to the soil pile system implementing multi-support excitation method. Spectral intensities of acceleration show that the extent of the response in sand is more severe than that of clay, in addition, increasing the PGA of ground strong motion will affect the sandy soil more, in comparison with clayey medium, which is an indicator of the sensitivity of soil-pile systems in sandy soil.

Keywords: BNWF method, multi-support excitation, nonlinear site response analysis, seismic soil-pile interaction

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156 Analysis of the Aquifer Vulnerability of a Miopliocene Arid Area Using Drastic and SI Models

Authors: H. Majour, L. Djabri

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Many methods in the groundwater vulnerability have been developed in the world (methods like PRAST, DRIST, APRON/ARAA, PRASTCHIM, GOD). In this study, our choice dealt with two recent complementary methods using category mapping of index with weighting criteria (Point County Systems Model MSCP) namely the standard DRASTIC method and SI (Susceptibility Index). At present, these two methods are the most used for the mapping of the intrinsic vulnerability of groundwater. Two classes of groundwater vulnerability in the Biskra sandy aquifer were identified by the DRASTIC method (average and high) and the SI method (very high and high). Integrated analysis has revealed that the high class is predominant for the DRASTIC method whereas for that of SI the preponderance is for the very high class. Furthermore, we notice that the method SI estimates better the vulnerability for the pollution in nitrates, with a rate of 85 % between the concentrations in nitrates of groundwater and the various established classes of vulnerability, against 75 % for the DRASTIC method. By including the land use parameter, the SI method produced more realistic results.

Keywords: GIS, Algeria, DRASTIC, Biskra sandy aquifer

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155 Effect of Compaction and Degree of Saturation on the Unconsolidated Undrained Shear Strength of Sandy Clay

Authors: Khalid Farooq, Fatima Mehmood, Rabeea Bakhtawer

Abstract:

For geotechnical engineers, one of the most important properties of soil to consider in various stability analyses is its shear strength which is governed by a number of factors. The objective of this research is to ascertain the effect of compaction and degree of saturation on the shear strength of fine-grained soil. For this purpose, three different dry densities such as in-situ, maximum standard proctor, and maximum modified proctor, were determined for the sandy clay soil. The soil samples were then prepared to keep dry density constant and varying degrees of saturation. These samples were tested for (UU) unconsolidated undrained shear strength in triaxial compression tests. The decrease in shear strength was observed with the decrease in density and increase in the saturation. The values of the angle of internal friction followed the same trend. However, the change in cohesion with the increase in saturation showed a different behavior, analogous to the compaction curve.

Keywords: Geotechnical investigation, laboratory testing, Shear Strength, compaction, degree of saturation, dry density

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154 An Overview of Pakistani Shales for Shale Gas Exploration and Comparison to North American Shale Plays

Authors: Ghulam Sohail, Christopher Hawkes

Abstract:

Pakistan has been facing a growing energy crisis for the last decade, and the government is seeking new horizons for increasing oil and gas production to reduce the gap between supply and demand. Recent developments in technologies to produce natural gas from shales at economical rates has unlocked new horizons for hydrocarbon exploration and development throughout the world. Operating companies in the U.S.A. and Canada have been particularly successful at producing shale gas, so comparing against the properties of shale gas reservoirs in these countries is used for an initial assessment of prospective shale gas reservoirs in other parts of the world. In this study, selected source rocks of Pakistan are evaluated for their shale gas potential using analogs selected from various North American shales for which data have been published. Published data for Pakistani shales were compiled, then assessed and supplemented through consultation with industry professionals. Pakistani formations reviewed are the Datta (shaly sandstone), Hangu (sandy shale), Patala (sandy shale), Ranikot (shaly sandstone), Sembar (sandy shale) and Lower Goru (shaly sandstone) formations, all of which are known source rocks in the Indus Basin. For this study, available geological, geochemical, petrophysical and elastic parameters have been investigated and are correlated specifically with the eight most active shale gas plays of the U.S.A., while data for other North American shale gas plays are used for general discussion on prospective Pakistani shales. The results show that the geological and geochemical parameters of all the Pakistani shales reviewed in this work are promising regarding their shale gas. However, more petrophysical and geomechanical data are required before conclusions on economic production from these shales can be made with confidence.

Keywords: indus basin, Canada shale gas, Pakistani shales, U.S.A shale gas

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153 Toxicological Analysis of Some Plant Combinations Used for the Treatment of Hypertension by Lay People in Northern Kwazulu-Natal, South Africa

Authors: Sandy Van Vuuren, Mmbulaheni Ramulondi, Helene De Wet

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The use of plant combinations to treat various medical conditions is not a new concept, and it is known that traditional people do not only rely on a single plant extract for efficacy but often combine various plant species for treatment. The knowledge of plant combinations is transferred from one generation to the other in the belief that combination therapy may enhance efficacy, reduce toxicity, decreases adverse effects, increase bioavailability and result in lower dosages. However, combination therapy may also be harmful when the interaction is antagonistic, since it may result in increasing toxicity. Although a fair amount of research has been done on the toxicity of medicinal plants, there is very little done on the toxicity of medicinal plants in combination. The aim of the study was to assess the toxicity potential of 19 plant combinations which have been documented as treatments of hypertension in northern KwaZulu-Natal by lay people. The aqueous extracts were assessed using two assays; the Brine shrimp assay (Artemia franciscana) and the Ames test (Mutagenicity). Only one plant combination (Aloe marlothii with Hypoxis hemerocallidea) in the current study has been previously assessed for toxicity. With the Brine shrimp assay, the plant combinations were tested in two concentrations (2 and 4 mg/ml), while for mutagenicity tests, they were tested at 5 mg/ml. The results showed that in the Brine shrimp assay, six combinations were toxic at 4 mg/ml. The combinations were Albertisia delagoensis with Senecio serratuloides (57%), Aloe marlothii with Catharanthus roseus (98%), Catharanthus roseus with Hypoxis hemerocallidea (66%), Catharanthus roseus with Musa acuminata (89%), Catharanthus roseus with Momordica balsamina (99%) and Aloe marlothii with Trichilia emetica and Hyphaene coriacea (50%). However when the concentration was reduced to 2 mg/ml, only three combinations were toxic which were Aloe marlothii with Catharanthus roseus (76%), Catharanthus roseus with Musa acuminata (66%) and Catharanthus roseus with Momordica balsamina (73%). For the mutagenicity assay, only the combinations between Catharanthus roseus with Hypoxis hemerocallidea and Catharanthus roseus with Momordica balsamina were mutagenic towards the Salmonella typhimurium strains TA98 and TA100. Most of the combinations which were toxic involve C. roseus which was also toxic when tested singularly. It is worth noting that C. roseus was one of the most frequently used plant species both to treat hypertension singularly and in combination and some of the individuals have been using this for the last 20 years. The mortality percentage of the Brine shrimp showed a significant correlation between dosage and toxicity thus toxicity was dosage dependant. A combination which is worth noting is the combination between A. delagoensis and S. serratuloides. Singularly these plants were non-toxic towards Brine shrimp, however their combination resulted in antagonism with the mortality rate of 57% at the total concentration of 4 mg/ml. Low toxicity was mostly observed, giving some validity to combined use, however the few combinations showing increased toxicity demonstrate the importance of analysing plant combinations.

Keywords: Toxicity, Hypertension, dosage, plant combinations

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152 The Role of Cornulaca aucheri in Stabilization of Degraded Sandy Soil in Kuwait

Authors: Modi M. Ahmed, Noor Al-Dousari, Ali M. Al-Dousari

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Cornulaca aucheri is an annual herb consider as disturbance indicator currently visible and widely distributed in disturbed lands in Liyah area. Such area is suffered from severe land degradation due to multiple interacting factors such as, overgrazing, gravel and sand quarrying, military activities and natural process. The restoration program is applied after refilled quarries sites and levelled the surface irregularities in order to rehabilitate the natural vegetation and wildlife to its original shape. During the past 10 years of rehabilitation, noticeable greenery healthy cover of Cornulaca sp. are shown specially around artificial lake and playas. The existence of such species in high density it means that restoration program has succeeded and transit from bare ground state to Cornulaca and annual forb state. This state is lower state of Range State Transition Succession model, but it is better than bare soil. Cornulaca spp is native desert plant grows in arid conditions on sandy, stony ground, near oasis, on sand dunes and in sandy depressions. The sheep and goats are repulsive of it. Despite its spiny leaves, it provides good grazing for camels and is said to increase the milk supply produced by lactating females. It is about 80 cm tall and has stems that branched from the base with new faster greenery growth in the summer. It shows good environmental potential to be managed as natural types used for the restoration of degraded lands in desert areas.

Keywords: Rehabilitation, Land Degradation, range state transition succession model, restoration program

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151 An Investigation of Wind Loading Effects on the Design of Elevated Steel Tanks with Lattice Tower Supporting Structures

Authors: J. van Vuuren, D. J. van Vuuren, R. Muigai

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In recent times, South Africa has experienced extensive droughts that created the need for reliable small water reservoirs. These reservoirs have comparatively quick fabrication and installation times compared to market alternatives. An elevated water tank has inherent potential energy, resulting in that no additional water pumps are required to sustain water pressure at the outlet point – thus ensuring that, without electricity, a water source is available. The initial construction formwork and the complex geometric shape of concrete towers that requires casting can become time-consuming, rendering steel towers preferable. Reinforced concrete foundations, cast in advance, are required to be of sufficient strength. Thereafter, the prefabricated steel supporting structure and tank, which consist of steel panels, can be assembled and erected on site within a couple of days. Due to the time effectiveness of this system, it has become a popular solution to aid drought-stricken areas. These sites are normally in rural, schools or farmland areas. As these tanks can contain up to 2000kL (approximately 19.62MN) of water, combined with supporting lattice steel structures ranging between 5m and 30m in height, failure of one of the supporting members will result in system failure. Thus, there is a need to gain a comprehensive understanding of the operation conditions because of wind loadings on both the tank and the supporting structure. The aim of the research is to investigate the relationship between the theoretical wind loading on a lattice steel tower in combination with an elevated sectional steel tank, and the current wind loading codes, as applicable to South Africa. The research compares the respective design parameters (both theoretical and wind loading codes) whereby FEA analyses are conducted on the various design solutions. The currently available wind loading codes are not sufficient to design slender cantilever latticed steel towers that support elevated water storage tanks. Numerous factors in the design codes are not comprehensively considered when designing the system as these codes are dependent on various assumptions. Factors that require investigation for the study are; the wind loading angle to the face of the structure that will result in maximum load; the internal structural effects on models with different bracing patterns; the loading influence of the aspect ratio of the tank; and the clearance height of the tank on the structural members. Wind loads, as the variable that results in the highest failure rate of cantilevered lattice steel tower structures, require greater understanding. This study aims to contribute towards the design process of elevated steel tanks with lattice tower supporting structures.

Keywords: aspect ratio, clearance height, wind loads, bracing patterns, elevated steel tanks, lattice steel tower

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