Search results for: soil pressure

Authors: K. Suresh, M. Padmavathi, N. Darga Kumar

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The objective of this study is to investigate the significance of coal mine waste and improved clay soil when used as a fill and for the construction of embankment. To determine the bearing capacities of coal mine waste and improved clay soil, tests are conducted apart from laboratory experiments. PLAXIS 2D software is used to make the analysis simpler. Depending upon the bearing capacities obtained for different cases, a conclusion can be drawn. Load carrying capacities are determined for coal mine waste, clay and by altering their height ratio when clay (H2) is at the bottom, and coal mine waste (H1) is on the top with three different cases (H = 0.25H1 + 0.75H2, 0.5H1 + 0.5H2, 0.75H1 + 0.25H2) in addition to this bearing capacity of improved clay soil (by replacing clay with 10% CMW, 30% CMW and 50% CMW in addition polycom) is also determined. The safe height of the embankment that can be constructed with the improved clay for different slopes, i.e., for 1:1, 1.5: 1, 2: 1 is also determined by using PLAXIS 2D software by limiting the factor of safety to 1.5.

Keywords: cohesion, angle of shearing resistance, elastic modulus, coefficient of consolidation, coal mine waste

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Authors: Ogan Karabas, Suleyman Yigit

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Number of blade and blade type of centrifugal fans are the most decisive factor on the field of application, noise level, suction pressure and outlet mass flow rate. Nowadays, in order to determine these effects on centrifugal fans, numerical studies are carried out in addition to experimental studies. In this study, it is aimed to numerically investigate the changes of suction pressure and outlet mass flow rate values of a centrifugal fan according to the number of blade and blade type. Centrifugal fans of the same size with forward, backward and straight blade type were analyzed by using a simulation program and compared with each other. This analysis was carried out under steady state condition by selecting k-Ɛ turbulence model and air is assumed incompressible. Then, 16, 32 and 48 blade centrifugal fans were again analyzed by using same simulation program, and the optimum number of blades was determined for the suction pressure and the outlet mass flow rate. According to the results of the analysis, it was obtained that the suction pressure in the 32 blade fan was twice the value obtained in the 16 blade fan. In addition, the outlet mass flow rate increased by 45% with the increase in the number of blade from 16 to 32. There is no significant change observed on the suction pressure and outlet mass flow rate when the number of blades increased from 32 to 48. In the light of the analysis results, the optimum blade number was determined as 32.

Keywords: blade type, centrifugal fan, cfd, outlet mass flow rate, suction pressure

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Authors: Waddah S. Abdullah, Saleh M. Al-Sarem

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Electrokinetic remediation of contaminated soils has undoubtedly proven to be one of the most efficient techniques used to clean up soils contaminated with polar contaminants (such as heavy metals) and nonpolar organic contaminants. It can efficiently be used to clean up low permeability mud, wastewater, electroplating wastes, sludge, and marine dredging. EK processes have proved to be superior to other conventional methods, such as the pump and treat, and soil washing, since these methods are ineffective in such cases. This paper describes the use of electrokinetic remediation to clean up soils contaminated with nickel. Open cells, as well as advanced cylindrical cells, were used to perform electrokinetic experiments. Azraq green clay (low permeability soil, taken from the east part of Jordan) was used for the experiments. The clayey soil was spiked with 500 ppm of nickel. The EK experiments were conducted under direct current of 80 mA and 50 mA. Chelating agents (NaEDTA), disodium ethylene diamine-tetra-ascetic acid was used to enhance the electroremediation processes. The effect of carbonates presence in soils was, also, investigated by use of sodium carbonate. pH changes in the anode and the cathode compartments were controlled by using buffer solutions. The results showed that the average removal efficiency was 64%, for the Nickel spiked saturated clayey soil.Experiment results have shown that carbonates retarded the remediation process of nickel contaminated soils. Na-EDTA effectively enhanced the decontamination process, with removal efficiency increased from 64% without using the NaEDTA to over 90% after using Na-EDTA.

Keywords: buffer solution, contaminated soils, EDTA enhancement, electrokinetic processes, Nickel contaminated soil, soil remediation

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Authors: B. Farahani, R. Fadil, A. Aboonabi, B. Hoffmann, J. Loscheider, K. Tavakolian, S. Arzanpour

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Wheelchair users spend long hours in a sitting position, and selecting the right cushion is highly critical in preventing pressure ulcers in that demographic. Pressure mapping systems (PMS) are typically used in clinical settings by therapists to identify the sitting profile and pressure points in the sitting area to select the cushion that fits the best for the users. A PMS is a flexible mat composed of arrays of distributed networks of flexible sensors. The output of the PMS systems is a color-coded image that shows the intensity of the pressure concentration. Therapists use the PMS images to compare different cushions fit for each user. This process is highly subjective and requires good visual memory for the best outcome. This paper aims to develop an image processing technique to analyze the images of PMS and provide an objective measure to assess the cushions based on their pressure distribution mappings. In this paper, we first reviewed the skeletal anatomy of the human sitting area and its relation to the PMS image. This knowledge is then used to identify the important features that must be considered in image processing. We then developed an algorithm based on those features to analyze the images and rank them according to their fit to the users' needs.

Keywords: dynamic cushion, image processing, pressure mapping system, wheelchair

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Authors: Jelena Bašić, Višnjica Vučetić, Mislav Anić, Tomislav Bašić

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Lack of precipitation combined with high temperatures causes great damage to the agriculture and economy in Croatia. Therefore, it is important to understand water circulation and balance. We decided to gain a better insight into the spatial distribution of water balance components (WBC) and their long-term changes in Croatia. WBC are precipitation (P), potential evapotranspiration (PET), actual evapotranspiration (ET), soil moisture content (S), runoff (RO), recharge (R), and soil moisture loss (L). Since measurements of the mentioned components in Croatia are very rare, the Palmer model has been applied to estimate them. We refined method by setting into the account the corrective factor to include influence effects of the wind as well as a maximum soil capacity for specific soil types. We will present one hundred years’ time series of PET and ET showing the trends at few meteorological stations and a comparison of components of two climatological periods. The meteorological data from 109 stations have been used for the spatial distribution map of the WBC of Croatia.

Keywords: croatia, long-term trends, the palmer method, water balance components

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Authors: Andres Zuñiga Orozco

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Green manure fertilizers have special importance in the development of organic and sustainable agriculture as a substitute or complement to chemical fertilization. They have many advantages, but they have application limitations in greenhouse crops and in open field crops that have low growing size. On the other hand, the logistics of sowing, harvesting and applying have been difficult for producers to adopt. For this reason, a pelletized presentation was designed in conjunction with Trichoderma harzianum. The biopellet was applied in pineapple as the first experience, managing to improve carbon levels in the soil and some nutrients. Then it was applied to tomatoes where it was proven that, nutritionally, it is possible to nourish the crop up to day 60 only with the biopellet, improve carbon levels in soil and control the fungus Fusarium oxysporum. Subsequently, it was applied to coffee seedlings with an organo-mineral formulation. Here, the improvement in the growth and nutrition of the plants was notable, as well as the increase in the microbial activity of the soil. M. pruriens biopellets allow crops to be nourished, allow biocontrolers to be added, improve soil conditions to promote greater microbial activity, reincorporate carbon and CO2 into the soil, are easily applicable, allow dosing and have a favorable shelf-life. They can be applied to all types of crops, both in the greenhouse and in the field.

Keywords: Mucuna pruriens, pellets, carbon, Trichoderma, Fusarium

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Authors: Stanis Koko Nyalongomo, Benjamin Mputela Bankanza, Moise Kisempa Mahungudi

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Several areas in the Democratic Republic of Congo (DRC) experience serious problems of streaming and soil erosion. Erosion leads to degradation of soil health, and the three main causative factors of similar importance are deforestation, overgrazing, and land agricultural mismanagement. Degradation of soil health leads to a decrease in agricultural productivity and carbon dioxide (CO₂), and other greenhouse gas emissions. Agricultural productivity low, and sanitation-related diseases are a concern of a majority of DRC rural people -whose main livelihoods are conventional smallholder agriculture- due to degradation of agricultural soil health and prevalence of inappropriate sanitation in rural areas. Land management practices that increase soil carbon stocks on agricultural lands with practices including conservation agriculture and agroforestry do not only limit CO₂ emissions but also help prevent erosion while enhancing soil health and productivity. Promotion to adopt sustainable land management practices, especially conversion to well-managed agroforestry practices, is a necessity. This needs to be accompanied by incentives. Methods that incite smallholders to adopt practices that increase carbon stocks in agricultural lands and enhance soil health and productivity for social, economic, and environmental benefits, and give them the ability to get and use household dry toilets -included activities to inform and raise smallholder households awareness on the conversion of croplands to well-managed agroforestry systems through planting at least 20 fruit trees and/or acacias, soil carbon and practices that sequester it in soil and ecological sanitation; and offer smallholders technique and material supports and incentives under the form of dry toilets constructed for free for well-managed agroforestry implementation- were carried out to address problems of soil erosion as well as agricultural productivity and sanitation-related diseases. In 2018 and 2019, 19 of 23 targeted smallholder households expressed their satisfaction and converted their croplands to agroforestry through planting 374 trees, and each gotten 1 dry toilet constructed for free. Their neighbors expressed a willingness to participate in the project. Conversion to well-managed agroforestry practices offers many advantages to both farmers and the environment. The strategy of offering smallholders incentives for soil-friendly agricultural practices, especially well-managed agroforestry, is one of the solutions to prevent soil erosion. DRC rural people whose majority are smallholder households, need to be able to get and use dry toilets. So, dry toilets could be offered like incentives for well-managed agroforestry practices. Given the many advantages agroforestry and dry toilet can offer, recommendations are made for funding organizations to support such projects that promote the adoption of soil health practices.

Keywords: agroforestry, croplands, soil carbon, soil health

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Authors: N. Abbas, S. Lagomarsino, S. Cattari

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Examining existing experimental results for shallow rigid foundations subjected to vertical centric load (N), accompanied or not with a bending moment (M), two main non-linear mechanisms governing the cyclic ‎response of the soil-foundation system can be distinguished: foundation uplift and soil yielding. A soil-foundation failure limit, is defined as a domain of resistance in the two dimensional (2D) load space (N, M) inside of which lie all the admissible combinations of loads; these latter correspond to a pure elastic, non-linear elastic or plastic behavior of the soil-foundation system, while the points lying on the failure limit correspond to a combination of loads leading to a failure of the soil-foundation system. In this study, the proposed resistance domain is constructed analytically based on mechanics. Original elastic limit, uplift initiation ‎limit and iso-uplift limits are constructed inside this domain. These limits give a prediction ‎of the mechanisms activated for each combination of loads applied to the ‎foundation. A comparison of the proposed failure limit with experimental tests existing in the literature shows interesting results. Also, the developed uplift initiation limit and iso-uplift curves are confronted with others already proposed in the literature and widely used due to the absence of other alternatives, and remarkable differences are noted, showing evident errors in the past proposals and relevant accuracy for those given in the present work.

Keywords: foundation uplift, iso-uplift curves, resistance domain, soil yield

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Authors: Ahmed El-Banbi, Ahmed El-Maraghi

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PVT properties are needed as input data in all reservoir, production, and surface facilities engineering calculations. In the absence of PVT reports on valid reservoir fluid samples, engineers rely on PVT correlations to generate the required PVT data. The accuracy of PVT correlations varies, and no correlation group has been found to provide accurate results for all oil types. The effect of inaccurate PVT data can be significant in engineering calculations and is well documented in the literature. Bubble point pressure can sometimes be obtained from external sources. In this paper, we show how to utilize the known bubble point pressure to improve the accuracy of calculated PVT properties from correlations. We conducted a systematic study using around 250 reservoir oil samples to quantify the effect of pre-knowledge of bubble point pressure. The samples spanned a wide range of oils, from very volatile oils to black oils and all the way to low-GOR oils. A method for shifting both undersaturated and saturated sections of the PVT properties curves to the correct bubble point is explained. Seven PVT correlation families were used in this study. All PVT properties (e.g., solution gas-oil ratio, formation volume factor, density, viscosity, and compressibility) were calculated using the correct bubble point pressure and the correlation estimated bubble point pressure. Comparisons between the calculated PVT properties and actual laboratory-measured values were made. It was found that pre-knowledge of bubble point pressure and using the shifting technique presented in the paper improved the correlation-estimated values by 10% to more than 30%. The most improvement was seen in the solution gas-oil ratio and formation volume factor.

Keywords: PVT data, PVT properties, PVT correlations, bubble point pressure

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Authors: Rabah Younes

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The reduction of available land resources and the increased cout associated with the use of high quality materials have led to the need for local soils to be used in geotechnical construction, however; poor engineering properties of these soils pose difficulties for constructions project and need to be stabilized to improve their properties in other works unsuitable soils with low bearing capacity , high plasticity coupled with high instability are frequently encountered hence, there is a need to improve the physical and mechanical characteristics of these soils to make theme more suitable for construction this can be done by using different mechanical and chemical methods clayey soil stabilization has been practiced for sometime but mixing additives, such us cement, lime and fly ash to the soil to increase its strength.

Keywords: clay, soil stabilization, naturaln pozzolana, atterberg limits, compaction, compressive strength shear strength, curing

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Authors: Messaoudi Mohammed Amin

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The reduction of available land resources and the increased cout associated with the use of hight quality materials have led to the need for local soils to be used in geotecgnical construction however, poor engineering properties of these soils pose difficulties for constructions project and need to be stabilized to improve their properties in oyher works unsuitable soils with low bearing capacity, high plasticity coupled with high insatbility are frequently encountered hense, there is a need to improve the physical and mechanical charateristics of these soils to make theme more suitable for construction this can be done by using different mechanical and chemical methods clayey soil stabilization has been practiced for quite sometime bu mixing additives, such us cement, lime and fly ash to the soil to increase its strength. The aim of this project is to study the effect of using lime, natural pozzolana or combination of both on the geotecgnical cherateristics of clayey soil. Test specimen were subjected to atterberg limits test, compaction test, box shear test and uncomfined compression test Lime or natural pozzolana was added to clayey soil at rangs of 0-8% and 0-20% respectively. In addition combinations of lime –natural pozzolana were added to clayey soil at the same ranges specimen were cured for 1-7, and 28 days after which they were tested for uncofined compression tests. Based on the experimental results, it was concluded that an important decrease of plasticity index was observed for thr samples stabilized with the combinition lime-natural pozzolana in addition, the use of the combination lime-natural pozzolana modifies the clayey soil classification according to casagrand plasiticity chart. Moreover, based on the favourable results of shear and compression strength obtained, it can be concluded that clayey soil can be successfuly stabilized by combined action of lime and natural pozzolana also this combination showed an appreciable improvement of the shear parameters. Finally, since natural pozzolana is much cheaper than lime ,the addition of natural pozzolana in lime soil mix may particulary become attractive and can result in cost reduction of construction.

Keywords: clay, soil stabilization, natural pozzolana, atterberg limits, compaction, compressive strength shear strength, curing

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Authors: K. Passbakhsh

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Determination of reinforcement forces is one of the most important and main discussions in designing retaining walls. By determining these forces we refrain from conservative planning. By numerically modeling the reinforced soil retaining walls under dynamic loading reinforcement forces can be calculated. In this study we try to approach the gained forces by pseudo-static method according to FHWA code and gained forces from numerical modeling by finite element method, by selecting seismic horizontal coefficient for different wall height. PLAXIS software was used for numerical analysis. Then the effect of reinforcement stiffness and soil type on reinforcement forces is examined.

Keywords: reinforced soil, PLAXIS, reinforcement forces, retaining walls

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Authors: Marija Vitanova, Aleksandra Bogdanovic, Kemal Edip, Viktor Hristovski, Vlado Micov

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Bridges represent critical structures in lifeline systems. They provide reliable modes of transportation, so their failure can seriously obstruct relief and rehabilitation work. Earthquake ground motions can cause significant damages in bridges, so during the strong earthquakes, they can easily collapse. The base isolation technique has been quite effective in seismic response mitigation of the bridges in reducing the piers base shear. The effect of soil structure interaction on the dynamic responses of seismically isolated three span girder bridge with viscous dampers is investigated. Viscous dampers are installed in the mid span of the bridge to control bearing displacement. The soil surrounding the foundation of piers has been analyzed by applying different soil densities in order to consider the soil stiffness. The soil medium has been assumed as a four layered infill as dense and loose medium. The boundaries in the soil medium are considered as infinite elements in order to absorb the radiating waves. The formulation of infinite elements is the same as for the finite elements in addition to the mapping of the domain. Based on the iso-parametric concept, the infinite element in global coordinate is mapped onto an element in local coordinate system. In the formulation of the infinite element, only the positive direction extends to infinity thus allowing the waves to propagate outside of the soil medium. Dynamic analyses for two levels of earthquake intensity are performed in time domain using direct integration method. In order to specify the effects of the SSI, the responses of the isolated and controlled isolated bridges are compared. It is observed that the soil surrounding the piers has significant effects on the bearing displacement of the isolated RC bridges. In addition, it is observed that the seismic responses of isolated RC bridge reduced significantly with the installation of the viscous dampers.

Keywords: viscous dampers, reinforced concrete girder bridges, seismic response, SSI

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Authors: Chinumani Choudhury

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Heavy metal contamination is an alarming problem, which poses a serious risk to human health and the surrounding geology. Soils get contaminated with heavy metals due to the un-regularized industrial discharge of the toxic metal-rich effluents. Under such a condition, the remediation of the contaminated sites becomes imperative for a sustainable, safe, and healthy environment. Phytoextraction, which involves the removal of heavy metals from the soil through root absorption and uptake, is a viable remediation technique, which ensures extraction of the toxic inorganic compound available in the soil even at low concentrations. The soil present in the Silghat Region of Assam, India, is mostly contaminated with Zinc (Zn) and Lead (Pb), having concentrations as high as to cause a serious environmental problem if proper measures are not taken. In the present study, an extensive experimental study was carried out to understand the effectiveness of two commonly planted trees in Assam, namely, i) Indian Pennywort and ii) Fenugreek, in the removal of heavy metals from the contaminated soil. The basic characterization of the soil in the contaminated site of the Silghat region was performed and the field concentration of Zn and Pb was recorded. Various long-term laboratory pot tests were carried out by sowing the seeds of Indian Pennywort and Fenugreek in a soil, which was spiked, with a very high dosage of Zn and Pb. The tests were carried out for different concentration of a particular heavy metal and the individual effectiveness in the absorption of the heavy metal by the plants were studied. The concentration of the soil was monitored regularly to assess the rate of depletion and the simultaneous uptake of the heavy metal from the soil to the plant. The amount of heavy metal uptake by the plant was also quantified by analyzing the plant sample at the end of the testing period. Finally, the study throws light on the applicability of the studied plants in the field for effective remediation of the contaminated sites of Assam.

Keywords: phytoextraction, heavy-metals, Indian pennywort, fenugreek

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Authors: Ajay Kumar, Shamily Jaggi

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In developing countries like India development of modern technologies has been a key determinant in accelerating industrialization and urbanization. But in the pursuit of rapid economic growth, development is considered a top priority, while environmental protection is not given the same importance. Thus, a number of industries sited haphazardly have been established, leading to a deterioration of natural resources like water, soil and air. As a result, environmental pollution is tremendously increasing due to industrialization and mechanization that are serving to fulfill the demands of the population. With the increasing population, demand for bricks for construction work is also increasing, establishing the brick industry as a growing industry. Brick production requires two main resources; water as a source of life, and soil, as a living environment. Water and soil conservation is a critical issue in areas facing scarcity of water and soil resources. The purpose of this review paper is to provide a brief overview of the theoretical frameworks used in the analysis of the adoption and/or acceptance of soil and water conservation practices in the brick industry. Different frameworks and models have been used in the analysis of the adoption and/or acceptance of new technologies and practices; these include the technology acceptance model, motivational model, theory of reasoned action, innovation diffusion theory, theory of planned behavior, and the unified theory of acceptance and use of technology. However, every model has some limitations, such as not considering environmental/contextual and economic factors that may affect the individual’s intention to perform a behavior. The paper concludes that in comparing other models, the UTAUT seems a better model for understanding the dynamics of acceptance and adoption of water and soil conservation practices.

Keywords: brick kiln, water conservation, soil conservation, unified theory of acceptance and use of technology, technology adoption

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Authors: Madhav Khadilkar

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Construction of a large standby reservoir was required to provide secure water supply. The new reservoir was required to be constructed at the same location of an abandoned old open pond due to space constraints. Some investigations were carried out earlier to improvise and re-commission the existing pond. But due to a lack of quantified risk of settlement from voids in the underlying limestone, the shallow foundations were not found feasible. Since the reservoir was resting on hard strata for about three-quarter of plan area and one quarter was resting on soil underlying with limestone and considerably low subgrade modulus. Further investigations were carried out to ascertain the locations and extent of voids within the limestone. It was concluded that the risk due to lime dissolution was acceptably low, and the site was found geotechnically feasible. The hazard posed by limestone dissolution was addressed through the integrated structural and geotechnical analysis and design approach. Finite Element Analysis was carried out to quantify the stresses and differential settlement due to various probable loads and soil-structure interaction. Walls behaving as cantilever under operational loads were found undergoing in-plane bending and tensile forces due to soil-structure interaction. Sensitivity analysis for varying soil subgrade modulus was carried out to check the variation in the response of the structure and magnitude of stresses developed. The base slab was additionally checked for the loss of soil contact due to lime pocket formations at random locations. The expansion and contraction joints were planned to receive minimal additional forces due to differential settlement. The reservoir was designed to sustain the actions corresponding to allowable deformation limits per code, and geotechnical measures were proposed to achieve the soil parameters set in structural analysis.

Keywords: differential settlement, limestone dissolution, reservoir, soil structure interaction

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Authors: Abbas Hani, Maryam Jassasizadeh

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The concentrations of Cd, Pb, and Ni were determined from 40 soil samples collected in surface soils of Khark Island. Geostatistic methods and GIS were used to identify heavy metal sources and their spatial pattern. Principal component analysis coupled with correlation between heavy metals showed that level of mentioned heavy metal was lower than the standard level. Then the data obtained from the soil analyzing were studied for the purposes of normal distribution. The best way of interior finding for cadmium and nickel was ordinary kriging and the best way of interpolation of lead was inverse distance weighted. The result of this study help us to understand heavy metals distribution and make decision for remediation of soil pollution.

Keywords: geostatistics, ordinary kriging, heavy metals, GIS, Khark

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Authors: A. Cervantes-Diaz, B. Sevilla-Moran, Manuel Alcami, Al Mokhtar Lamsabhi, J. L. Alonso-Prados, P. Sandin-España

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Profoxydim is a post-emergence herbicide belonging to the cyclohexanedione oxime family, used to control weeds in rice crops. The use of soil organic amendments has increased significantly in the last decades, and their effects on the behavior of many herbicides are still unknown. Additionally, it is known that photolysis is an important degradation process to be considered when evaluating the persistence of this family of herbicides in the environment. In this work, the photodegradation of profoxydim in an amended paddy soil-water system with alperujo compost was studied. Photodegradation experiments were carried out under laboratory conditions using simulated solar light (Suntest equipment) in order to evaluate the reaction kinetics of the active substance. The photochemical behavior of profoxydim was investigated in soil with and without alperujo amendment. Furthermore, due to the rice crop characteristics, profoxydim photodegradation in water in contact with these types of soils was also studied. Determination of profoxydim degradation kinetics was performed by High-Performance Liquid Chromatography with Diode-Array Detection (HPLC-DAD). Furthermore, we followed the evolution of resulting transformation by-products, and their tentative identification was achieved by mass spectrometry. All the experiments allowed us to fit the data of profoxydim photodegradation to a first-order kinetic. Photodegradation of profoxydim was very rapid in all cases. The half-lives in aqueous matrices were in the range of 86±0.3 to 103±0.5 min. The addition of alperujo amendment to the soil produced an increase in the half-life from 62±0.2 min (soil) to 75±0.3 min (amended soil). In addition, a comparison to other organic amendments was also performed. Results showed that the presence of the organic amendment retarded the photodegradation in paddy soil and water. Regarding degradation products, the main process involved was the cleavage of the oxime moiety giving rise to the formation of the corresponding imine compound.

Keywords: by-products, herbicide, organic amendment, photodegradation, profoxydim

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Authors: Samriti Wadhwa, Beena Kumari

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Background and Significance: Residue levels of ready mix (chlorpyriphos 50% and cypermethrin 5%), cypermethrin and chlorpyriphos individually in sandy loam soil under okra fruits (Variety, Varsha Uphar) were determined; a field experiment was conducted at Research Farm of Department of Entomology of Chaudhary Charan Singh Haryana Agriculture University, Hisar, Haryana, India. Persistence behavior of cypermethrin and chlorpyriphos was studied following application of a pre-mix formulation of insecticides viz. Action-505EC, chlorpyriphos (Radar 20 EC) and cypermethrin (Cyperkill 10 EC) at the recommended dose and double the recommended dose along with control at fruiting stage. Pesticide application also leads to decline in soil acarine fauna which is instrumental in the breakdown of the litter because of which minerals are released into the soil. So, by this study, one can evaluate the safety of pesticides for the soil health. Methodology: Action-505EC (chlorpyriphos 50% and cypermethrin 5%) at 275 g a .i. ha⁻¹ (single dose) and 550 g a. i. ha⁻¹ (double dose), chlorpyriphos (Radar 20 EC) at 200 g a. i. ha⁻¹ (single dose) and 400 g a. i. ha⁻¹ (double dose) and cypermethrin (Cyperkill 10 EC) at 50 g a. i. ha⁻¹ (single dose) and 100 g a. i. ha⁻¹ (double dose) were applied at the fruiting stage on okra crop. Samples of soils from okra field were collected periodically at 0 (1h after spray), 1, 3, 5, 7, 10, 15 days and at harvest after application as well of control soil sample. After air drying, adsorbing through Florisil and activated charcoal and eluting with hexane: acetone (9:1) then residues in soils were estimated by a gas chromatograph equipped with a capillary column and electron capture detector. Results: No persistence of cypermethrin in ready-mix in soil under okra fruits at single and double dose was observed. In case of chlorpyriphos in ready-mix, average initial deposits on 0 (1 h after treatment) day was 0.015 mg kg⁻¹ and 0.036 mg kg⁻¹ which persisted up to 5 days and up to 7 days for single and double dose, respectively. After that residues reached below a detectable level of 0.010 mg kg⁻¹. Experimental studies on cypermethrin individually revealed that average initial deposits on 0 (1 h after treatment) were 0.008 mg kg⁻¹ and 0.012 mg kg⁻¹ which persisted up to 3 days and 5 days for single and double dose, respectively after that residues reached to below detectable level. The initial deposits of chlorpyriphos individually in soil were found to be 0.055 mg kg⁻¹ and 0.113 mg kg⁻¹ which persisted up to 7 days and 10 days at a lower dose and higher dose, respectively after that residues reached to below determination level. Conclusion: In soil under okra crop, only individual cypermethrin in both the doses persisted whereas no persistence of cypermethrin in ready-mix was observed. Persistence of chlorpyriphos individually is more as compared to chlorpyriphos in ready-mix in both the doses. Overall, the persistence of chlorpyriphos in soil under okra crop is more than cypermethrin.

Keywords: chlorpyriphos, cypermethrin, okra, ready mix, soil

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Authors: Jacqueline Miller, Dongyuan Y. Wang, F. Dan Richard

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Before trying to make an ethical machine that holds a higher ethical standard than humans, a better understanding of human moral standards that could be used as a guide is crucial. How humans make decisions in dangerous driving situations like moral dilemmas can contribute to developing acceptable ethical principles for autonomous vehicles (AVs). This study uses a driving simulator to investigate whether drivers make utilitarian choices (choices that maximize lives saved and minimize harm) in unavoidable automobile accidents (moral dilemmas) with time pressure manipulated. This study also investigates how impulsiveness influences drivers’ behavior in moral dilemmas. Manipulating time pressure results in collisions that occur at varying time intervals (4 s, 5 s, 7s). Manipulating time pressure helps investigate how time pressure may influence drivers’ response behavior. Thirty-one undergraduates participated in this study using a STISM driving simulator to respond to driving moral dilemmas. The results indicated that the percentage of utilitarian choices generally increased when given more time to respond (from 4 s to 7 s). Additionally, participants in vehicle scenarios preferred responding right over responding left. Impulsiveness did not influence utilitarian choices. However, as time pressure decreased, response time increased. Findings have potential implications and applications on the regulation of driver assistance technologies and AVs.

Keywords: time pressure, automobile moral dilemmas, impulsiveness, reaction time

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Authors: Chioma Nwakanma, Onyeka Okoh Irene, Emmanuel Eze

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Pesticide residues left in agricultural soils after cropping are always accumulative, difficult to degrade and harmful to animals, plants, soil and human health in general. The biodegrading potential of pesticides- resistant PGPB on soil pollution was investigated using in situ remediation technique following recommended standards. In addition, screening for insecticide utilization, maximum insecticide concentration tolerance, insecticide biodegradation and insecticide residues analyses via gas chromatographic/electron column detector were determined. The location of bacterial degradation genes was also determined. Three plant growth-promoting rhizophere (PGPR) were isolated and identified according to 16S rRNA as Paraburkholderia tropica, Burkolderia glumae and Achromobacter insolitus. From the results, all the three isolates showed phosphate solubilizing traits and were able to grow on nitrogen free medium. The isolates were able to utilize the insecticide as sole carbon source and increase in biomass. They were statistically significantly tolerant to all the insecticide concentrations screened. The gas chromatographic profiles of the insecticide residues showed a reduction in the peak areas of the insecticides, indicating degradation. The bacterial consortium had the lowest peak areas, showing the highest degradation efficiency. The genes responsible for degradation were found to be in the plasmids of the isolates. Therefore, the use of PGPR is recommended for bioremediation of agricultural soil insecticide polluted areas and can also enhance soil fertility.

Keywords: biodegradation, rhizosphere, insecticides utilization, agricultural soil

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Authors: Varun K, Pramod B. Balareddy

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Estimation of wind forces plays a significant role in the in the design of large antenna parabolic reflectors. Reflector surface accuracies are very sensitive to the gain of the antenna system at higher frequencies. Hence accurate estimation of wind forces becomes important, which is primary input for design and analysis of the reflector system. In the present work, numerical simulation of wind flow using Computational Fluid Dynamics (CFD) software is used to investigate the external pressure coefficients. An extensive comparative study has been made between the CFD results and the published wind tunnel data for different wind angle of attacks (α) acting over concave to convex surfaces respectively. Flow simulations using CFD are carried out to estimate the coefficients of Drag, Lift and Moment for the parabolic reflector. Coefficients of pressures (Cp) over the front and the rear face of the reflector are extracted over surface of the reflector to study the net pressure variations. These resultant pressure variations are compared with the published wind tunnel data for different angle of attacks. It was observed from the CFD simulations, both convex and concave face of reflector system experience a band of pressure variations for the positive and negative angle of attacks respectively. In the published wind tunnel data, Pressure variations over convex surfaces are assumed to be uniform and vice versa. Chordwise and spanwise pressure variations were calculated and compared with the published experimental data. In the present work, it was observed that the maximum pressure coefficients for α ranging from +30° to -90° and α=+90° was lower. For α ranging from +45° to +75°, maximum pressure coefficients were higher as compared to wind tunnel data. This variation is due to non-uniform pressure distribution observed over front and back faces of reflector. Variations in Cd, Cl and Cm over α=+90° to α=-90° was in close resemblance with the experimental data.

Keywords: angle of attack, drag coefficient, lift coefficient, pressure coefficient

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Authors: S. Ansari Sadrabadi, G. H. Rahimi

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In this paper, thick walled Cylindrical tanks or tubes made of functionally graded material under internal pressure and temperature gradient are studied. Material parameters have been considered as power functions. They play important role in the elastoplastic behavior of these materials. To clarify their role, different materials with different parameters have been used under temperature gradient. Finally, their effect and loading effect have been determined in first yield point. Also, the important role of temperature gradient was also shown. At the end the study has been results obtained from changes in the elastic modulus and yield stress. Also special attention is also given to the effects of this internal pressure and temperature gradient in the creation of tensile and compressive stresses.

Keywords: FGM, cylindrical pressure tubes, small deformation theory, yield onset, thermal loading

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Authors: Mihretu Erjabo

Abstract:

Halaba special district is characterized by drought, soil erosion, high population pressure, poor livestock production, lack of feed for livestock, very deep water table, very low productivity of crops and food insufficiency. In order to address these problems, the woreda agricultural development office along with other management practices such as soil physical conservation measures agroforestry was introduced decades ago as a means to alleviate the problem. However, the level of agroforestry adoption remains low. Objective of this study was to identify the factors that influence adoption of agroforestry technologies by farmers in the district. Random sampling was employed to select two kebele administrations and respondents. Data collection was conducted by rural household questionnaire survey, participatory rural appraisal, questionnaires for local and woreda extension staff, secondary data resources and field observation. A sample of 12 key informants, 6 extension staffs, and 182 households, were used in the data collection. Chi square test used to determine significant relationships between adoption of agroforestry and 15 selected variables. Out of which eleven were found to be significant to affect farmers’ adoptiveness. These were frequency of visits of farmers (13.39%), participation in training (11.49%), farmers’ attitude towards agroforestry practices (10.61%), frequency of visits of extensionists (10.38%), participation in extension meeting (10.34%), participation in field day (10.28%), land holding size (9.29%), level of literacy (8.78%), awareness about the importance of agroforestry technology packages (7.06%), time taken from their residence to nearest extension (5.04%) and gender of respondents (3.34%). This study also identified various factors that result in low adoption rates of agroforestry including fear of competition, seedling, rainfall and labour shortage, free grazing, financial problem, expecting trees as soil degrader and long span of trees and lack of need ranking. To improve farmers’ adoption, the factors identified should be well addressed by launching a series and recurrent outreach extension program appropriate and suitable to farmers need.

Keywords: farmers attitude, farmers participation, soil degradation, technology packages

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Authors: Mehrak Zargaryaeghoubi, Masood Hajali

Abstract:

Drilled shafts are the most popular of deep foundations, because they have the capability that one single shaft can easily carry the entire load of a large column from a bridge or tall building. Drilled shaft may be an economical alternative to pile foundations because a pile cap is not needed, which not only reduces that expense, but also provides a rough surface in the border of soil and concrete to carry a more axial load. Due to the larger construction sizes of drilled shafts, they have an excellent axial load carrying capacity. Part of the axial load carrying capacity of the drilled shaft is resisted by the soil below the tip of the shaft which is tip resistance and the other part is resisted by the friction developed around the drilled shaft which is side resistance. The condition at the bottom of the excavation can affect the end bearing capacity of the drilled shaft. Also, type of the soil and size of the drilled shaft can affect the frictional resistance. The main loads applied on the drilled shafts are axial compressive loads. It is important to know how many percent of the maximum applied load will be shed inside friction and how much will be transferred to the base. The axial capacity of the drilled shaft foundation is influenced by the size of the drilled shaft, and soil characteristics. In this study, the effect of the size and soil characteristic will be investigated on the contribution of side resistance and end-bearing capacity. Also, the study presents a three-dimensional finite element modeling of a drilled shaft subjected to axial load using ANSYS. The top displacement and settlement of the drilled shaft are verified with analytical results. The soil profile is considered as Table 1 and for a drilled shaft with 7 ft diameter and 95 ft length the stresses in z-direction are calculated through the length of the shaft. From the stresses in z-direction through the length of the shaft the side resistance can be calculated and with the z-direction stress at the tip, the tip resistance can be calculated. The result of the side and tip resistance for this drilled shaft are compared with the analytical results.

Keywords: Drilled Shaft Foundation, size and soil characteristic, axial load capacity, Finite Element

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Authors: Shuo Wang

Abstract:

The hydrogeological parameters of the engineering site and the hydraulic connection between the aquifers can be obtained by the pumping test. Through the recovery test, the characteristics of water level recovery and the law of surface subsidence recovery can be understood. The above two tests can provide the basis for subsequent engineering design. At present, the deformation of deep soil caused by pumping tests is often neglected. However, some studies have shown that the maximum settlement subject to groundwater drawdown is not necessarily on the surface but in the deep soil. In addition, the law of settlement recovery of each soil layer subject to water level recovery is not clear. If the deformation-sensitive structure is deep in the test site, safety accidents may occur. In this study, the pumping test and recovery test of a confined aquifer in Shanghai are introduced. The law of measured groundwater changes and surface subsidence are analyzed. In addition, the fluid-solid coupling model was established by ABAQUS based on the Biot consolidation theory. The models are verified by comparing the computed and measured results. Further, the variation law of water level and the deformation law of deep soil during pumping and recovery tests under different site conditions and different times and spaces are discussed through the above model. It is found that the maximum soil settlement caused by pumping in a confined aquifer is related to the permeability of the overlying aquitard and pumping time. There is a lag between soil deformation and groundwater changes, and the recovery rate of settlement deformation of each soil layer caused by the rise of water level is different. Finally, some possible research directions are proposed to provide new ideas for academic research in this field.

Keywords: coupled hydro-mechanical analysis, deep ground settlement, numerical simulation, pumping test, recovery test

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Authors: Magdi M. E. Zumrawi, Mohamed Awad

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Determination of Resilient Modulus (M_R) is quite important for characterizing materials in pavement design and evaluation. The main focus of this study is to develop a correlation that predict the resilient modulus of subgrade soils from simple and easy measured soil index properties. To achieve this objective, three subgrade soils representing typical Khartoum soils were selected and tested in the laboratory for measuring resilient modulus. Other basic laboratory tests were conducted on the soils to determine their physical properties. Several soil samples were prepared and compacted at different moisture contents and dry densities and then tested using resilient modulus testing machine. Based on experimental results, linear relationship of M_R with the consistency factor ‘F_c’ which is a combination of dry density, void ratio and consistency index had been developed. The results revealed that very good linear relationship found between the M_R and the consistency factor with a coefficient of linearity (R²) more than 0.9. The consistency factor could be used for the prediction of the M_R of compacted subgrade soils with precise and reliable results.

Keywords: Consistency factor, resilient modulus, subgrade soil, properties

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Authors: P. Hari Prasad Reddy, Shimna Paulose, V. Sai Kumar, C. H. Rama Vara Prasad

Abstract:

Soil environment gets contaminated due to rapid industrialisation, agricultural-chemical application and improper disposal of waste generated by the society. Unexpected volume changes can occur in soil in the presence of certain contaminants usually after the long duration of interaction. Alkali is one of the major soil contaminant that has a considerable effect on behaviour of soils and capable of inducing swelling potential in soil. Chemical heaving of clayey soils occurs when they are wetted by aqueous solutions of alkalis. Mineralogical composition of the soil is one of the main factors influencing soil- alkali interaction. In the present work, studies are carried out to understand the swell potential of soils due to soil-alkali interaction with different concentrations of NaOH solution. Locally available soil, namely, red earth containing kaolinite which is of non-swelling nature is selected for the study. In addition to this, two commercially available clayey soils, namely ball clay and china clay containing mainly of kaolinite are selected to understand the effect of alkali interaction in various kaolinitic soils. Non-swelling red earth shows maximum swell at lower concentrations of alkali solution (0.1N) and a slightly decreasing trend of swelling with further increase in concentration (1N, 4N, and 8N). Marginal decrease in swell potential with increase in concentration indicates that the increased concentration of alkali solution exists as free solution in case of red earth. China clay and ball clay both falling under kaolinite group of clay minerals, show swelling with alkaline solution. At lower concentrations of alkali solution both the soils shows similar swell behaviour, but at higher concentration of alkali solution ball clay shows high swell potential compared to china clay which may be due to lack of well ordered crystallinity in ball clay compared to china clay. The variations in the results obtained were corroborated by carrying XRD and SEM studies.

Keywords: alkali, kaolinite, swell potential, XRD, SEM

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Authors: R. Ziaie Moayed, H. Keshavarz Hedayati

Abstract:

Over recent years, due to increased population and increased waste production, groundwater protection has become more important, therefore, designing engineered barrier systems such as landfill liners to prevent the entry of leachate into groundwater should be done with greater accuracy. These measures generally involve the application of low permeability soils such as clays. Bentonite is a natural clay with low permeability which makes it a suitable soil for using in liners. Also zeolite with high cation exchange capacity can help to reduce of hazardous materials risk. Bentonite expands when wet, absorbing as much as several times its dry mass in water. This property may effect on some structural properties of soil such as shear strength. In present study, shear strength parameters are determined by both leachates polluted and not polluted bentonite-amended zeolite soil with mixing rates (B/Z) of 5%-10% and 20% with unconfined compression test to obtain the differences. It is shown that leachate presence causes reduction in resistance in general.

Keywords: bentonite, leachate, shear strength parameters, unconfined compression test

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Authors: Noureddine Litim

Abstract:

This work is to theoretical and numerical studying the real analysis of the seismic response of the soil with an Elasto-plastic behavior. To perform this analysis, we used different core drilling performed at the tunnel T4 in El Horace section of the highway east-west. The two-dimensional model (2d) was established by the code of finite element plaxis to estimate the displacement amplification and accelerations caused by the seismic wave in the different core drilling and compared with the factor of acceleration given by the RPA (2003) in the area studying. Estimate the displacement amplification and accelerations caused by the seismic wave.

Keywords: seismic response, deposition of soil, plaxis, elasto-plastic

Procedia PDF Downloads 106