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1
Hamad, Asal Mahmud, i Mahmood Gazey Jassam. "A Comparative Study for the Effect of Some Petroleum Products on the Engineering Properties of Gypseous Soils". Tikrit Journal of Engineering Sciences 29, nr 3 (15.10.2022): 69. http://dx.doi.org/10.25130/tjes.29.3.7.
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Gypseous soils are considered problematic soils because the soil cavities happen during receiving the water or this type of soil and solving gypsum materials and contract in a soil volume. In this study, three types of gypseous soils are used; soil1, soil2, and soil3 with gypsum content (28.71%, 43.6%, and 54.88%) respectively, petroleum products (engine oil, fuel oil, and kerosene) are added to the soils with percentages (3%, 6%, 9%, and 12%) for each product. The result showed that specific gravity, liquid limit, optimum moisture content (O.M.C), and maximum dry density decreased with an increased percentage of product for all types of products. The direct shear (dry and soaked case) results show that increasing the (angle of internal friction and the soil cohesion) for soil1, soil2, and soil3 by adding engine oil and fuel oil. Still, when the soils were treated with kerosene, the angle of internal friction increased while cohesion decreased. The collapse potential for the treated soils increases with increasing gypsum content for all petroleum products. The collapse potential (CP) for (soil1) decreased by 47% when using 6% of the engine oil, 48.8% when using 9% of the fuel oil, and 55% when using 9% of the kerosene. The same percentage of the petroleum products (engine oil, fuel oil, and kerosene) decrease the collapse potential for (soil2), (47%, 46%, and 50%) respectively and decrease the collapse potential for (soil 3), (51%, 47.7%, and 52%) respectively. In the unconfined compressive test applied on (soil1) using maximum density, the results show that the soil strength increased (26% and 10%) when using 6% and engine oil and fuel oil, respectively, while the soil strength decreased by 29% when treated with 9% of kerosene.
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Leonard, R. A. "Soil and Water Conservation Engineering". Journal of Environmental Quality 23, nr 2 (marzec 1994): 390. http://dx.doi.org/10.2134/jeq1994.00472425002300020032x.
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BORAH, DEVA K. "Soil and Water Conservation Engineering". Soil Science 156, nr 3 (wrzesień 1993): 209–11. http://dx.doi.org/10.1097/00010694-199309000-00013.
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Hadas, A. "Soil and water conservation engineering". Soil and Tillage Research 32, nr 1 (październik 1994): 88–89. http://dx.doi.org/10.1016/0167-1987(94)90036-1.
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Fredlund, Delwyn G. "The 1999 R.M. Hardy Lecture: The implementation of unsaturated soil mechanics into geotechnical engineering". Canadian Geotechnical Journal 37, nr 5 (1.10.2000): 963–86. http://dx.doi.org/10.1139/t00-026.
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The implementation of unsaturated soil mechanics into geotechnical engineering practice requires that there be a paradigm shift from classical soil mechanics methodology. The primary drawback to implementation has been the excessive costs required to experimentally measure unsaturated soil properties. The use of the soil-water characteristic curve has been shown to be the key to the implementation of unsaturated soil mechanics. Numerous techniques have been proposed and studied for the assessment of the soil-water characteristic curves. These techniques range from direct laboratory measurement to indirect estimation from grain-size curves and knowledge-based database systems. The soil-water characteristic curve can then be used for the estimation of unsaturated soil property functions. Theoretically based techniques have been proposed for the estimation of soil property functions such as (i) coefficient of permeability, (ii) water storage modulus, and (iii) shear strength. Gradually these estimations are producing acceptable procedures for geotechnical engineering practices for unsaturated soils. The moisture flux ground surface boundary condition is likewise becoming a part of the solution of most problems involving unsaturated soils. The implementation process for unsaturated soils will still require years of collaboration between researchers and practicing geotechnical engineers.Key words: unsaturated soil mechanics, soil suction, unsaturated soil property functions, negative pore-water pressure, matric suction, soil-water characteristic curve.
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Han, Zhen, Jiangwen Li, Pengfei Gao, Bangwei Huang, Jiupai Ni i Chaofu Wei. "Determining the Shear Strength and Permeability of Soils for Engineering of New Paddy Field Construction in a Hilly Mountainous Region of Southwestern China". International Journal of Environmental Research and Public Health 17, nr 5 (28.02.2020): 1555. http://dx.doi.org/10.3390/ijerph17051555.
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As a constructed wetland ecosystem, paddy field plays an irreplaceable role in flood storage and detention, groundwater replenishment, environmental protection, and ecological balance maintenance. New paddy field construction can give full play to the production and ecological functions of paddy field and can adjust the development structure of the agricultural industry effectively. The soil properties of shear strength and permeability, which provide a theoretical basis for engineering design, construction, and post-operation, are important indexes in the site selection of new paddy field. The shear strength and permeability properties of soils from different land use types (vegetable field, gentle slope dryland, corn field, grapery, and abandoned dryland) for engineering new paddy field construction were investigated in this study. The results showed that the soil water content had a significant effect on the soil shear strength, internal friction angle, and cohesion. The total pressure required for soil destruction decreased with increasing water content under the same vertical pressure, resulting in easier destruction of soils. The internal friction angle decreased with increasing soil water content, and the soil cohesion first increased and then decreased with increasing soil water content. Considering that paddy fields were flooded for a long time, the soil strength properties had certain water sensitivity. Effective measures must be taken to reduce the change in soil water content, so as to ensure the stability of the embankment foundation, roadside ditch foundation, and cutting slope. In addition, the influence of changing soil water content on the strength properties of paddy soils should be fully considered in engineering design and construction, and the soil bulk density at the plough pan should reach at least 1.5 g cm−3 or more to ensure better water retention and the anti-seepage function of paddy field. The study can provide construction technology for engineering new paddy field construction in a hilly mountainous region of southwestern China.
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Liu, Hao, Zheng Huang, Wen Qi, Han Shi i Lijuan Yao. "Study on the Engineering Properties of Waste Soil-Based Flowable Fill". Journal of Physics: Conference Series 2468, nr 1 (1.04.2023): 012092. http://dx.doi.org/10.1088/1742-6596/2468/1/012092.
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Abstract Flowable fill is developed mainly for the difficult backfilling and compaction such as side trenches of foundation pits and retaining wall backfills. It can make use of waste soils. It has good flowability before curing, and thus can be compacted by its own weight. It also has high strength after curing. In this study, by using on-site waste soils as the raw material soil, 25 groups of flowable fill experiments were carried out. The relationship between flowability, strength and mix ratio of flowable fills was analyzed. The results show that the flowability of flowable fill increases with the increase of water-soil ratio and decreases with the increase of cement-soil ratio. It shows that the water-soil ratio is the main control index of its flowability. The strength of flowable fill increases with the increase of cement-soil ratio, and decreases with the increase of water-soil ratio. The water-cement ratio can be used as the main control index for the strength of the material within the tested range.
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Dong, Yi, Changfu Wei i Ning Lu. "Identifying Soil Adsorptive Water by Soil Water Density". Journal of Geotechnical and Geoenvironmental Engineering 146, nr 7 (lipiec 2020): 02820001. http://dx.doi.org/10.1061/(asce)gt.1943-5606.0002289.
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Fleming, P. M. "Elementary soil and water engineering (3rd edition)". Agricultural Water Management 12, nr 3 (kwiecień 1987): 250. http://dx.doi.org/10.1016/0378-3774(87)90017-5.
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Alzaidy, Mohammed Nawaf Jirjees. "A Theoretical Study of Some Unsaturated Properties for Different Soils". Journal of University of Babylon for Engineering Sciences 26, nr 9 (1.11.2018): 149–65. http://dx.doi.org/10.29196/jubes.v26i9.1720.
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Soil–water characteristic curves (SWCC) can be defined as the relationship between the water content and suction of an unsaturated soil. It considered a basic relation to explanation of the engineering behaviour of unsaturated soil such as hydraulic conductivity and shear strength, So the study of SWCC is useful to reduce the time and cost of unsaturated soil testing for different engineering purposes. An approach model has been used to predict the SWCC for different soils. The influence of the soils on SWCC shape, the unsaturated hydraulic conductivity and shear strength parameters have been studied in this paper using mathematical models. The results of SWCC show that suction of clay soil is bigger than sandy soil, while the clayey silt soils exhibit an intermediate behaviour at same water content. The values of unsaturated shear strength are increasing while the unsaturated hydraulic conductivity is decreasing with increasing soil suction. This behaviour of the last two parameters with soil suction should be taken in consideration for engineering purposes.
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Al-Obaidi, Anwar, Alaa Ihssan i Hamed Allawi. "Studying of the combined salts effect on the engineering properties of clayey soil". MATEC Web of Conferences 162 (2018): 01011. http://dx.doi.org/10.1051/matecconf/201816201011.
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In recent years, a number of studies had been performed to investigate the effect of pore water chemistry on the strength and compressibility characteristics of soil. Although the effect of chloride and sulfates salts separately in pore fluids on the geotechnical properties of soil seems to be well understood, but the influence of combined effect of sulfates and chlorides in pore water on the behavior of soil is still unclear mostly due to the limited numbers of studies as well as the complexity of processes that may occur in soil (with the presence of salts) in pore water-soil interaction. Southern regions of Iraq, especially Basra suffers from low water levels in the summer season in addition to the lack of rain water, which causes a significant increase of salt in the Shatt al Arab. Water salinity continues to increase with time. To investigate the combined impacts of water salinity on the behavior of clayey soils, the basic characteristics of the soil brought from Al-Nahrawan site was studied. Chemical methods were done with three types of water (distilled, water of highly saline as Shatt Al-Arab water and water of Tarmiya as moderate saline water). The effect of water salinity on the geotechnical properties of fine grain soil was investigated. Different laboratory tests such as Atterberg limits, standard compaction, consolidation and shear strength of soil .Results showed that the presence of perceptible amounts of dissolved salts in water can lead to changes in the engineering properties of the soil.
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Tao, Gaoliang, Da Lei, Lisheng Liu, Yi Li i Xueliang Zhu. "Prediction of Soil Water Characteristic Curve Based on Soil Water Evaporation". Advances in Civil Engineering 2021 (1.03.2021): 1–14. http://dx.doi.org/10.1155/2021/6686442.
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Soil water characteristic curves (SWCC) and soil water evaporation curves both represent the laws of water content variation in the natural state. Aiming to investigate the relationship between them further, Hunan sand with six dry densities were used in this study, and a series of experimental studies were performed. This study developed the application of evaporation curves in geotechnical engineering, reduced the workload of measuring soil water characteristic curves, and explored the relationship between evaporation rate and fractal dimension. Through the indoor tests, we measured soil water characteristic curves of specimens and soil water evaporation curves at different temperatures and explored the relationship between these two curves. In this study, a model was developed that allows the conversion from soil water evaporation curves to soil water characteristic curves, which is an equation about matrix suction ψ versus cumulative time t. Further, two prediction methods are developed, which are derived based on the Fredlund–Xing model and based on the Bird model, respectively. The proposed methods were validated using soil water evaporation tests of Hunan sand with six dry densities at three ambient temperatures, and the results showed that good prediction performances were achieved using these two methods.
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Iqbal, Prahara, Dicky Muslim, Zufialdi Zakaria, Haryadi Permana i Yunarto Yunarto. "RELATIONSHIP BETWEEN SOIL ENGINEERING PROPERTIES AND CORROSION RATE IN ANDESITIC VOLCANIC SOILS, WEST LAMPUNG, SUMATRA, INDONESIA". Jurnal Teknologi 83, nr 1 (7.12.2020): 117–25. http://dx.doi.org/10.11113/jurnalteknologi.v83.14924.
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Soil is the most diverse environment that can cause metal corrosion. Many researchers claim that soil is a corrosive environment that has complexity compared to other environments. With a background knowledge of soil engineering properties in a specific area and their effects on the metal corrosion process then corrosion problems can be prevented. This paper presents the relationship between andesitic volcanic soil engineering properties with an average corrosion rate based on geotechnical and statistical methods. In this paper, we propose a new average corrosion rate per year on that soil. The study area took place on the Sekincau-Way Tenong Transect Road, West Lampung, Sumatra, Indonesia. This area was composed of silty clay to clayey silt soils which weathering products from andesitic-basaltic volcanic breccia. This soil can store water that is moderate to high and has high plastic properties. Based on the statistical approach, it can be concluded that the corrosion rate in andesitic volcanic soils is 1.132 mm/yr. Soil engineering properties (water content, index plasticity, and clay content) simultaneously affect the average corrosion rate. The effective contribution of each independent variable (soil engineering properties) to the corrosion rate is a plasticity index of 39.5%, the water content of 24.79%, and clay content of 26.04%. Index plasticity and water content were found to raise the average corrosion rate at the soil samples, while clay content was on the side that lowered the average corrosion rate.
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Yu, Jianlin, Zihao Mao, Jiajin Zhou, Zhongxiang Yu, Xiangwu Liu i Xiaonan Gong. "Experimental Study on Engineering Properties of Cemented Soil with High Water Content". Applied Sciences 13, nr 2 (10.01.2023): 937. http://dx.doi.org/10.3390/app13020937.
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A series of unconsolidated-undrained triaxial tests and unconfined compressive strength (UCS) tests for cemented soils with different curing times were carried out in this research. In total, three cemented soil mixtures with different cement contents were adopted in the tests, and the confining pressure was controlled in the range of 100–1600 kPa. The influence of curing time, cemented soil mixture ratio and confining pressure on the compressive and shear capacity of cemented soil was analyzed based on the test results. The test results indicate that the cement content and curing time both had a great influence on the strength of cemented soil, the UCS of the cemented soil increased linearly with the curing time under the semi-logarithmic coordinate, the cemented soil exhibited strain softening characteristics in the axial shear tests, and the maximum deviatoric stress of the cemented soil increased with the increase in confining pressure. A linear correlation was found between the cohesion and the UCS of cemented soil, and the cohesion was about 0.40 times the compressive strength.
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Barbour, S. Lee. "Nineteenth Canadian Geotechnical Colloquium: The soil-water characteristic curve: a historical perspective". Canadian Geotechnical Journal 35, nr 5 (1.10.1998): 873–94. http://dx.doi.org/10.1139/t98-040.
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The constitutive relationship between water content or degree of saturation and suction is called the soil-water characteristic curve. The soil-water characteristic curve provides a conceptual framework in which the behavior of unsaturated soils can be understood. A historical review illustrates how the work of early researchers in soil science and geotechnical engineering laid the foundation for our current understanding of this relationship. Key elements of these early studies were a conceptual understanding of the soil-water characteristic curve as a relationship between the mass or volume of water stored within the soil and the energy in the water phase. It was on the basis of this conceptual model that current methods of measuring the soil-water characteristic curve were developed. Interpretative models for the distribution and geometry of the water phase in an unsaturated soil based on the capillary model have provided a useful conceptual model for understanding the effects of soil texture, gradation, void ratio, and compaction on the soil-water characteristic curve. The capillary model has also provided the foundation for recently developed techniques to predict the functional relationship between degree of saturation and shear strength, coefficient of permeability, coefficient of diffusion, and adsorption for unsaturated soils.Key words: unsaturated soils, soil-water characteristic curve, suction, shear strength, permeability, contaminant transport.
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Ci, Jun, i Yuan Fang Zhang. "Application of Stabilizer to Improvement the Saline Soil in Lor Nur Lacustrine". Advanced Materials Research 912-914 (kwiecień 2014): 53–56. http://dx.doi.org/10.4028/www.scientific.net/amr.912-914.53.
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Considering the Lop Nur Lacustrine plain saline soil is a special soil which with poor engineering properties such as collapsible and expansion. Through an experimental research on the saline soils stabilized by lime, cement and a polymeric solidified material was conducted. The unconfined compressive strengths and water-related stability of stabilized saline soils were discussed. It was shown that unconfined compressive strength and water-related stability of stabilized Lacustrine plain saline soils attained corresponding engineering standards and that it could be used as roadbed fillings., which could provide a reference to prevent and treatment about the dangers of Lop Nur Lacustrine plain saline soil.
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Zhang, Ling Ling, Jian Hua Fan i Yan Ge Zhang. "The Substantial Base of Water-Salt’s Migration in Dispersive Saline Soil and its Influence on Geotechnical Engineering". Applied Mechanics and Materials 105-107 (wrzesień 2011): 1448–51. http://dx.doi.org/10.4028/www.scientific.net/amm.105-107.1448.
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This paper is based on a series of experiments on saline soil which is sampled from the west of Jilin province. Through analysis of the properties of material composition, we reveals the inner connection between the dispersivity of saline soil and the soil’s practical environment and material composition, which has theoretical and practical significance in engineering practice and study of saline soil’s dispersivity in this area .This paper will help us fully understand the characteristics of dispersive saline soil and the way it behaviors in engineering for taking the feasible engineering countermeasures to cope with saline soil and engineering accidents caused by the dispersivity of saline soils. The results of this paper will bring engineering applications of dispersive saline soil to a new level.
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Fredlund, Delwyn G., Daichao Sheng i Jidong Zhao. "Estimation of soil suction from the soil-water characteristic curve". Canadian Geotechnical Journal 48, nr 2 (luty 2011): 186–98. http://dx.doi.org/10.1139/t10-060.
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Soil-water characteristic curves (SWCCs) are routinely used for the estimation of unsaturated soil property functions (e.g., permeability functions, water storage functions, shear strength functions, and thermal property functions). This paper examines the possibility of using the SWCC for the estimation of in situ soil suction. The paper focuses on the limitations of estimating soil suctions from the SWCC and also suggests a context under which soil suction estimations should be used. The potential range of estimated suction values is known to be large because of hysteresis between drying and wetting SWCCs. For this, and other reasons, the estimation of in situ suctions from the SWCC has been discouraged. However, a framework is suggested in this paper for estimating the median value for in situ soil suction along with a likely range of soil suction values (i.e., maximum and minimum values). The percentage error in the estimation of soil suction from the SWCC is shown to be lowest for sand soils and highest for clay soils.
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Silva, Luana da, Jackson Adriano Albuquerque, Letícia Sequinatto i Diego Bortolini. "Adjusting the water retention curve for retractable soils". DYNA 88, nr 218 (20.08.2021): 136–42. http://dx.doi.org/10.15446/dyna.v88n218.89499.
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The soil water retention curve (SWRC) relates moisture to soil water retention energy (matrix potential). The calculation of the volumetrichumidity considers the sample volume. In retractable soils, this volume varies according to the drying or wetting of the soil, which can result in errors in the calculated moisture. The objective of this study is to quantify the volume variation in retractable soils and to elaborate the SWRC via the traditional method, which does not consider soil retraction, and a second method, called adjusted, that considers thephenomenon of soil retraction. Soil samples have been collected in horizons A and B from six soil profiles Thus, for retractable soils, it isrecommended that the adjustment of the SWRC be carried out considering the actual volume of the soil (retracted), which varies for each matrix potential applied. This adjustment reduces errors, mainly in determining the permanent wilt point and available water.
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Hoque, Mehrin, Akhila Palat i Michael Hendry. "A Preliminary Study on the Engineering Properties of Clay Soil". Alberta Academic Review 2, nr 2 (10.09.2019): 39–40. http://dx.doi.org/10.29173/aar47.
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Karl Von Terzaghi, the father of soil mechanics, says, “There is no other soil which is as problematic as clay soil”. In many places across the badlands of Alberta, clay soil is known to be troublesome and cause issues with buildings and infrastructure. Climate conditions, erosion and weathering can cause the unstable clay soil to create landslides, which consequently damage many of these structures. For this reason, engineers are sent to these sites to monitor and collect data over a period of time to compare and contrast their results. The purpose of this study is to learn and understand the properties of clay soils through different classification and index tests. Two clay soils, kaolinite and bentonite, were tested for their properties and their results were compared. Some of the tests performed include the hydrometer analysis, pycnometer analysis, and atterberg limits. The hydrometer analysis is the process in determining the size of silts and clays (when sieves cannot be used). The pycnometer analysis is used to determine the specific gravity of a substance. Atterberg limits are used to determine the water content at which a soil starts to shift from liquid, plastic or semi-solid. These tests were done in two different solutions - one containing distilled water and one with saline water - to understand the effect of the solution on the liquid and plastic limits. The goal of this study was achieved and the results can be used to understand more about the engineering properties of clay soils and apply these studies to future field work. By understanding these properties, further research can be done to discover long term solutions to landslides caused by the problematic soil.
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Dewangan, Shailesh Kumar. "Using the Soil Texture Triangle to Evaluate the Effect of Soil Texture on Water Flow: A Review". International Journal for Research in Applied Science and Engineering Technology 11, nr 6 (30.06.2023): 389–93. http://dx.doi.org/10.22214/ijraset.2023.53635.
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Abstract: Water flow through soil is a critical process that affects many aspects of soil health and environmental sustainability. Soil texture, which is the relative proportion of sand, silt, and clay particles in soil, plays a significant role in regulating water flow through soils. The soil texture triangle is a widely used tool for classifying soil texture based on the proportions of sand, silt, and clay particles. This review paper aims to evaluate the effect of soil texture on water flow through soils using the soil texture triangle. The paper presents an overview of the soil texture triangle and its applications in soil texture classification, followed by a discussion of the relationship between soil texture and water flow. The paper reviews existing literature on the impact of soil texture on water flow and summarizes the key findings. The review highlights the importance of soil texture in regulating water flow through soils and discusses the implications for soil management and environmental sustainability. The paper concludes by identifying areas for future research to improve our understanding of the relationship between soil texture and water flow.
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Rodiya, Adeniyi Afolabi, Daudua Aluyah Okodugha, Emmanuel Aleonolu Adoga, Samuel Olaiya i Michael Okafor. "An assessment of physical properties and water holding capacity of soil under different fertilizer applications". Studia Universitatis Babeș-Bolyai Engineering 66, nr 1 (9.11.2021): 25–33. http://dx.doi.org/10.24193/subbeng.2021.1.3.
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This study was carried out at the Teaching and Research Farm of the Department of Agricultural and Bio-Environmental Engineering, School of Engineering, The Federal Polytechnic, Ado-Ekiti to evaluate the water holding capacities of soil under different fertilizers. The experiment was laid out in randomized complete block design (RCBD). The treatments: control, poultry waste, biochar and urea fertilizer replicated four times were incorporated into the soil and maize seed planted. Data collected were subjected to statistical analysis. Soil samples were analyzed for moisture contents, bulk densities, particle densities and water holding capacities. Maize yield was also analyzed. The result obtained showed a significant (p< 0.05) changes in maize yield for the different fertilizers. It also shows a non-significant (p<0.05) effect on water holding capacities of the soils incorporated with different fertilizers. The study concluded that fertilizers has no effect on the water holding capacity of the soil and that poultry waste amended soil will produce higher yield.
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Singh, Gajendra. "Elementary Soil and Water Engineering. 3rd ed. 1985". Soil Science 143, nr 2 (luty 1987): 155. http://dx.doi.org/10.1097/00010694-198702000-00013.
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Hasegawa, S. "Soil and water engineering for paddy field management". Agricultural Water Management 26, nr 1-2 (wrzesień 1994): 149–50. http://dx.doi.org/10.1016/0378-3774(94)90030-2.
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Wang, Dong Lin. "Experimental Study on Soil Water Characteristic Curve of Compacted Unsaturated Soil". Advanced Materials Research 168-170 (grudzień 2010): 1285–88. http://dx.doi.org/10.4028/www.scientific.net/amr.168-170.1285.
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Soil water characteristic curve is one of important topics of unsaturated soils. Pressure plate extractor and GDS unsaturated triaxial apparatus are used to study influencing factors including types of soils and net mean stress. Through method of least-squares, Fredlund five-parameter model were employed to fit soil-water characteristic curves. The results show that model provided a satisfactory fit to the experimental data. Through an analysis of influencing factors, we find that not only physical condition of samples but also external stress condition can affect the shape of soil water characteristic curve.
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Khanzode, R. M., S. K. Vanapalli i D. G. Fredlund. "Measurement of soil-water characteristic curves for fine-grained soils using a small-scale centrifuge". Canadian Geotechnical Journal 39, nr 5 (1.10.2002): 1209–17. http://dx.doi.org/10.1139/t02-060.
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Considerably long periods of time are required to measure soil-water characteristic curves using conventional equipment such as pressure plate apparatus or a Tempe cell. A commercially available, small-scale medical centrifuge with a swinging type rotor assembly was used to measure the soil-water characteristic curves on statically compacted, fine-grained soil specimens. A specimen holder was specially designed to obtain multiple sets of water content versus suction data for measuring the soil-water characteristic curve at a single speed of rotation of the centrifuge. The soil-water characteristic curves were measured for three different types of fine-grained soils. The three soils used in the study were processed silt (liquid limit, wL = 24%; plasticity index, Ip = 0; and clay = 7%), Indian Head till (wL = 35.5%, Ip = 17%, and clay = 30%), and Regina clay (wL = 75.5%, Ip = 21%, and clay = 70%). The soil-water characteristic curves for the above soils were measured in 0.5, 1, and 2 days, respectively, using the centrifuge technique for suction ranges from 0 to 600 kPa. Time periods of 2, 46, and 16 weeks were required for measuring the soil-water characteristic curves for the same soils using a conventional pressure plate apparatus. There is reasonably good agreement between the experimental results obtained by the centrifuge and the pressure plate methods. The results of this study are encouraging as soil-water characteristic curves can be measured in a reduced time period when using a small-scale centrifuge.Key words: unsaturated soils, soil-water characteristic curve, centrifuge technique, soil suction, matric suction, water content.
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DeJong, Jason T., Kenichi Soga, Steven A. Banwart, W. Richard Whalley, Timothy R. Ginn, Douglas C. Nelson, Brina M. Mortensen, Brian C. Martinez i Tammer Barkouki. "Soil engineering in vivo : harnessing natural biogeochemical systems for sustainable, multi-functional engineering solutions". Journal of The Royal Society Interface 8, nr 54 (9.09.2010): 1–15. http://dx.doi.org/10.1098/rsif.2010.0270.
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Carbon sequestration, infrastructure rehabilitation, brownfields clean-up, hazardous waste disposal, water resources protection and global warming—these twenty-first century challenges can neither be solved by the high-energy consumptive practices that hallmark industry today, nor by minor tweaking or optimization of these processes. A more radical, holistic approach is required to develop the sustainable solutions society needs. Most of the above challenges occur within, are supported on, are enabled by or grown from soil. Soil, contrary to conventional civil engineering thought, is a living system host to multiple simultaneous processes. It is proposed herein that ‘soil engineering in vivo ’, wherein the natural capacity of soil as a living ecosystem is used to provide multiple solutions simultaneously, may provide new, innovative, sustainable solutions to some of these great challenges of the twenty-first century. This requires a multi-disciplinary perspective that embraces the science of biology, chemistry and physics and applies this knowledge to provide multi-functional civil and environmental engineering designs for the soil environment. For example, can native soil bacterial species moderate the carbonate cycle in soils to simultaneously solidify liquefiable soil, immobilize reactive heavy metals and sequester carbon—effectively providing civil engineering functionality while clarifying the ground water and removing carbon from the atmosphere? Exploration of these ideas has begun in earnest in recent years. This paper explores the potential, challenges and opportunities of this new field, and highlights one biogeochemical function of soil that has shown promise and is developing rapidly as a new technology. The example is used to propose a generalized approach in which the potential of this new field can be fully realized.
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Fredlund, D. G., Anqing Xing, M. D. Fredlund i S. L. Barbour. "The relationship of the unsaturated soil shear strength to the soil-water characteristic curve". Canadian Geotechnical Journal 33, nr 3 (2.07.1996): 440–48. http://dx.doi.org/10.1139/t96-065.
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The measurement of soil parameters, such as the permeability and shear strength functions, used to describe unsaturate soil behaviour can be expensive, difficult, and often impractical to obtain. This paper proposes a model for predicting the shear strength (versus matric suction) function of unsaturated soils. The prediction model uses the soil-water characteristic curve and the shear strength parameters of the saturated soil (i.e., effective cohesion and effective angle of internal friction). Once a reasonable estimate of the soil-water characteristic curve is obtained, satisfactory predictions of the shear strength function can be made for the unsaturated soil. Closed-form solutions for the shear strength function of unsaturated soils are obtained for cases where a simple soil-water characteristic equation is used in the prediction model. Key words: soil suction, soil-water characteristic curve, shear strength function, unsaturated soil.
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Orfanus, Tomas, Abdel-Monem Mohamed Amer, Grzegorz Jozefaciuk, Emil Fulajtar i Anežka Čelková. "Water vapour adsorption on water repellent sandy soils". Journal of Hydrology and Hydromechanics 65, nr 4 (20.12.2017): 395–401. http://dx.doi.org/10.1515/johh-2017-0030.
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AbstractSoil sorptivity is considered a key parameter describing early stages of water (rain) infiltration into a relatively dry soil and it is related to build-up complexity of the capillary system and soil wettability (contact angles of soil pore walls). During the last decade an increasing water repellency of sandy soils under pine forest and grassland vegetation has been frequently observed at Mlaky II location in SW Slovakia. The dry seasons result in uneven wetting of soil and up to hundredfold decrease in soil sorptivity in these vegetated soil as compared to reference sandy material, which was out of the reach of ambient vegetation and therefore readily wettable. As far as water binding to low moisture soils is governed by adsorption processes, we hypothesized that soil water repellency detected by water drop penetration test and by index of water repellency should also influence the water vapour adsorption parameters (monolayer water content, Wm, specific surface area, A, maximum adsorption water, Wa, maximum hygroscopic water MH, fractal dimension, DS and adsorption energies, Ea) derived from BET model of adsorption isotherms. We found however, that the connection of these parameters to water repellency level is difficult to interpret; nevertheless the centres with higher adsorption energy prevailed evidently in wettable materials. The water repellent forest and grassland soils reached less than 80% of the adsorption energy measured on wettable reference material. To get more conclusive results, which would not be influenced by small but still present variability of field materials, commercially available homogeneous siliceous sand was artificially hydrophobized and studied in the same way, as were the field materials. This extremely water repellent material had two-times lower surface area, very low fractal dimension (close to 2) and substantially lower adsorption energy as compared to the same siliceous sand when not hydrophobized.
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Xu, Xu, Fu You Zhang i Ming Gu. "Experimental Research on Soil-Water Characteristic Curve of Unsaturated Soils". Applied Mechanics and Materials 353-356 (sierpień 2013): 554–57. http://dx.doi.org/10.4028/www.scientific.net/amm.353-356.554.
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The soil-water characteristic curve (SWCC) reflects water storage capacity, Measuring it accurately is important in engineering. This paper concluded main factors of SWCC, measured soil-water characteristic of loess under conditions of different dry densities, the curve of volume water content, saturation and matric suction were presented, the curves showed similar change trend, saturation mainly determined the matric suction when matric suction was small.
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Li, Xiaopeng, Scott X. Chang i K. Francis Salifu. "Soil texture and layering effects on water and salt dynamics in the presence of a water table: a review". Environmental Reviews 22, nr 1 (marzec 2014): 41–50. http://dx.doi.org/10.1139/er-2013-0035.
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Soil texture and its vertical spatial heterogeneity may greatly influence soil hydraulic properties and the distribution of water and solutes in the soil profile; therefore, they are of great importance for agricultural, environmental, and geo-engineering applications such as land reclamation and landfill construction. This paper reviews the following aspects on water and salt dynamics in the presence of a water table: (i) the effect of soil texture on the extent of upward movement of groundwater in homogenous soils and (ii) the impact of soil textural layering on water and salt dynamics. For a homogenous soil, the maximum height of capillary rise (hmax) or the evaporation characteristic length (ECL) is closely related to the soil texture. When the water table is deeper than hmax, water will evaporate at some depth below surface and salts will be retained below the evaporation front, causing the separation of water and salt. For layered soils, flow barriers (capillary and hydraulic barriers) can make the soil hold more water than a nonlayered one. A capillary barrier may work when a fine-textured layer overlies a coarse-textured layer during infiltration or a coarse-textured layer overlies a fine-textured layer during evaporation, and a hydraulic barrier may occur when a poorly permeable layer exists in the soil profile. The extra water held by flow barriers may improve water availability to plants and may at the same time increase salinization and other environmental risks. Under special conditions, such as in seasonally frozen soils with a shallow water table, there is an additional soil salinization incentive caused by freeze–thaw cycles. Above all, further research is needed to understand the complex effects of soil texture and layering on water and salt dynamics, especially in artificial soils such as reclaimed soils with contrasting properties.
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Kaya, Abidin, i Hsai-Yang Fang. "Experimental evidence of reduction in attractive and repulsive forces between clay particles permeated with organic liquids". Canadian Geotechnical Journal 42, nr 2 (1.04.2005): 632–40. http://dx.doi.org/10.1139/t04-099.
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Researchers have investigated the engineering properties of clayey soils with organic fluids to evaluate the performance of earth structures affected by chemical spills or leachate. Reported results show that when the pore water of clayey soils was replaced with organic liquids, the engineering properties of clayey soils, such as hydraulic conductivity and stressstrain behavior, varied significantly and were similar to those of fine sand silt. Variations in the engineering properties were mainly attributed to flocculation of particles due to decreases in the attractive and repulsive forces between the particles without showing any direct experimental evidence. In this study, flocculation of kaolinite and bentonite particles was investigated in the presence of water and organic liquids using an optical microscope (OM), and the first experimental evidence of soil flocculation due to pore fluid is presented. The OM results reveal that when the pore water of the soil is replaced with organic fluids, the soil particles flocculate and form a clustered structure with large pores within the flocs. The results also indicated that the degree of flocculation and the size of the formed cluster depend on the type of clay mineral and the characteristics of the organic liquid.Key words: clayey soils, organic liquids, engineering properties, attractive and repulsive forces, optical microscope.
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Pham, Hung Q., i Delwyn G. Fredlund. "Volume–mass unsaturated soil constitutive model for drying–wetting under isotropic loading–unloading conditions". Canadian Geotechnical Journal 48, nr 2 (1.02.2011): 280–313. http://dx.doi.org/10.1139/t10-061.
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A rigorous volume–mass constitutive model is proposed for the representation of drying–wetting under isotropic loading–unloading conditions for unsaturated soils. The proposed model utilizes concepts arising from soil physics and geotechnical engineering research and requires readily obtainable soils data for soil properties. The model can be used to predict void ratio and water content constitutive relationships (and therefore degree of saturation) for a wide range of unsaturated soils. Various stress paths (i.e., loading–unloading and drying–wetting) can be simulated, and hysteresis associated with the soil-water characteristic curve is taken into account. Two closed-form equations for the volume–mass constitutive relationships are presented for soils starting from slurry conditions. A number of test results (i.e., from experimental programs reported in the research literature) were used during the verification of the proposed volume–mass constitutive model. The volume–mass constitutive model captures key unsaturated soil conditions such as air-entry value, water-entry value, and residual conditions. The proposed model appears to satisfactorily predict unsaturated soil behavior for soils ranging from low compressible sands to high compressible clays.
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Fredlund, D. G., i Anqing Xing. "Equations for the soil-water characteristic curve". Canadian Geotechnical Journal 31, nr 4 (1.08.1994): 521–32. http://dx.doi.org/10.1139/t94-061.
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The soil-water characteristic curve can be used to estimate various parameters used to describe unsaturated soil behaviour. A general equation for the soil-water characteristic curve is proposed. A nonlinear, least-squares computer program is used to determine the best-fit parameters for experimental data presented in the literature. The equation is based on the assumption that the shape of the soil-water characteristic curve is dependent upon the pore-size distribution of the soil (i.e., the desaturation is a function of the pore-size distribution). The equation has the form of an integrated frequency distribution curve. The equation provides a good fit for sand, silt, and clay soils over the entire suction range from 0 to 106 kPa. Key words : soil-water characteristic curve, pore-size distribution, nonlinear curve fitting, soil suction, water content.
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Sillers, W. Scott, i Delwyn G. Fredlund. "Statistical assessment of soil-water characteristic curve models for geotechnical engineering". Canadian Geotechnical Journal 38, nr 6 (1.12.2001): 1297–313. http://dx.doi.org/10.1139/t01-066.
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A number of empirical equations have been proposed for the soil-water characteristic curve. A nonlinear, least squares method was used to determine best-fit parameters for several empirical equations that were best-fit to 230 water content versus soil suction data sets. In addition, two proposed correction methods to accommodate high soil suctions up to 1 000 000 kPa were applied to the various soil-water characteristic curve equations. The data sets of water content versus soil suction were arranged into one of the USDA soil classifications based on their relative amounts of sand, silt, and clay (only eight soil classifications had sufficient data for later analysis). The quality of fit for each model was compared using the Akaike Information Criterion. A series of conclusions were arrived at regarding (i) the relationship between two- and three-parameter equations, (ii) the relationship between exponential and sigmoidal type equations, and (iii) the value of correction factors for the high soil suction range.Key words: soil-water characteristic curve, unsaturated soil, soil suction, regression analysis, SWCC models, Akaike Information Criterion.
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Su, Dong Yang, i Gui Sheng Fan. "The Effect of Gypsum on High Saline Soil’s Infiltration Capability and Soil Improvement". Advanced Materials Research 183-185 (styczeń 2011): 61–64. http://dx.doi.org/10.4028/www.scientific.net/amr.183-185.61.
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Soil water infiltration is an important link of the natural water cycle. Infiltration is the inherent properties of soils. It determines the speed and distribution of the irrigation water converted to soil water. Then affected the irrigation’s quality and effect. Especially for high saline soil infiltration of improvement has profound significance. Gypsum improving is a chemical measures to improve high saline soils and has a remarkable effect on soil water infiltration. It can improve saline land with the help of other measures.
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Pires, Luiz F., i Fábio A. M. Cássaro. "Nuclear Laboratory Setup for Measuring the Soil Water Content in Engineering Physics Teaching Laboratories". AgriEngineering 5, nr 2 (15.06.2023): 1079–89. http://dx.doi.org/10.3390/agriengineering5020068.
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Soil water content (θ) is a crucial soil parameter that is determined in many studies involving engineering, geology, and soil and environmental sciences. For instance, evaluating the soil strength, groundwater recharge, hydraulic conductivity, and soil aeration status depends on θ. The measurement of θ is fundamental for monitoring and controlling several soil processes. The gamma-ray attenuation (GRA) technique is a fast and non-destructive way of evaluating θ in soils with very contrasting compositions. Although, GRA is rarely explored in lab physics classes. The proposal of an experiment using a teaching GRA apparatus for measuring θ is presented. The experimental setup consisted of a 137Cs radioactive source, a Geiger-Müller detector, and a radiation counter. Soil samples with four distinct granulometric compositions were analyzed. Strong linear correlations were found between the transmitted gamma-ray photon intensity and θ (correlation coefficients varying from −0.95 to −0.98). The soil porosity, measured by the conventional and GRA methods, presented differences that varied from c. 7.8% to c. 18.2%. In addition, strong linear relationships (correlation coefficients from 0.90 to 0.98) were observed between the GRA and the traditional (gravimetric) method of θ measurement. It was verified that the teaching GRA apparatus is useful for measuring θ. In addition, the apparatus allows the introduction of some important aspects related to the study of modern physics for undergraduate students of many fields of knowledge.
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Puppala, Anand J., Koonnamas Punthutaecha i Sai K. Vanapalli. "Soil-Water Characteristic Curves of Stabilized Expansive Soils". Journal of Geotechnical and Geoenvironmental Engineering 132, nr 6 (czerwiec 2006): 736–51. http://dx.doi.org/10.1061/(asce)1090-0241(2006)132:6(736).
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Ferreira, Silvio R. M., Lícia M. Costa, Leonardo J. N. Guimarães i Ivaldo D. S. P. Filho. "Volume Change Behavior due to Water Content Variation in an Expansive Soil from the Semiarid Region of Pernambuco - Brazil". Soils and Rocks 36, nr 2 (1.05.2013): 183–93. http://dx.doi.org/10.28927/sr.362183.
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One of the most important morphological characteristics of expansive soil is contracting and fissuring during drying and swelling during wetting. Soils that change volume when inundated with water require extra care, whether they are used in agriculture, engineering or both. In this paper, conventional and suction-controlled oedometric tests were used to evaluate the changes in volume and swelling pressure caused by changes in water content in an expansive soil from Petrolândia-PE. A coupled hydro-mechanical formulation, implemented in the computational code CODE_BRIGHT, was applied to simulate the tests performed with this soil. The constitutive model used was the double structure generalized plasticity model proposed by Sanchez et al. (2005). The results show that soil expansion, contraction and collapse depend on the initial water content and the external load applied. The conclusion is that volume changes due to water content variation are associated with the initial conditions of the soil and the load applied to the soil. The experimental data and simulation results are in good agreement, showing that the model and computer code are able to accurately represent the hydro-mechanical behavior of expansive soils.
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Lei, Lei, Ji Ming Song, Jin Wang, Shu Hai Zheng, Feng Yi Li i Hao Wan. "Baihetan - Jiangsu engineering soil and water conservation online monitoring data system". Journal of Physics: Conference Series 2428, nr 1 (1.02.2023): 012026. http://dx.doi.org/10.1088/1742-6596/2428/1/012026.
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Abstract Baihetan - Jiangsu ± 800kV UHVDC project can improve the power supply stability of the hydropower station, which has very important economic significance. The construction of power transmission projects will affect the water and soil conservation situation along the site. Currently, the commonly used monitoring methods are based on manual data collection with low accuracy and a large workload. Therefore, the government vigorously promotes the development of intelligent water conservancy and strives to improve the digitalization degree of water and soil monitoring systems. In this paper, the traditional chain pin method was improved, using the photosensitive chain pin and ultrasonic chain pin instead of the ordinary chain pin. Then calculated the soil erosion modulus by collecting the soil loss index of the measured point, and uploading it to the cloud for analysis by the radio transmission device, so that the monitor system obtained accurate soil loss data. Finally, the system is applied to the baihetan-Jiangsu soil and water conservation monitoring project, and the monitoring data of soil and water conservation of the two stations are obtained. Combined with the local meteorological conditions, we can analyze the causes of soil and water loss, and give the corresponding prevention measures.
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Th. Al-Hadidi, Maysam, i Atheer G. Ibrahim. "Improvement of Gypsum Soil by Using Polyurethane to Reduce Erosion and Solubility of Irrigation Canals". International Journal of Engineering & Technology 7, nr 4.20 (28.11.2018): 372. http://dx.doi.org/10.14419/ijet.v7i4.20.26137.
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The reducing of erosion and the solubility of irrigation canals soils which constructed on gypsum soil is important in civil and water resources engineering. The main problem of gypsum soils is the presence of gypsum which represents one of most complex engineering problems, especially when accompanied by the moving of water which represent dynamic load along the canal. There are several solutions to this problem, in this research “Poly urethane” is used to give the gypsum soil sufficient hardness to reduce the solubility and erosion, after compacting the soil in the canal, percentages of Poly urethane was used to making cover to the soil by mixing percent of soil with Poly urethane, and the ratio was as follows: (5 and 10) % and the percent of Poly urethane were as follows: 6%, 10%, and 12%. The collapsibility of the soil was calculated by measuring the height of the soil after the passage of water along the canal. This collapsibility was used as an index to calculate the erosion and the solubility of gypsum within the soil. The results show that the best percentage of poly urethane is (10%), which gave small value in corrosion about (3%) at 28 days.
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Abdulla, Rozan, i Nadhmiah Majeed. "Enhancing Engineering Properties of Expansive Soil Using Marble Waste Powder". Iraqi Geological Journal 54, nr 1E (31.05.2021): 43–53. http://dx.doi.org/10.46717/igj.54.1e.4ms-2021-05-25.
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Owing to its propensity to swell when in contact with water, expansive soil causes severe structural problems and shrinks when they dry out. Soil stabilization is a well-known method used to enhance the soil's physical and engineering properties and is commonly adopted for improving soil structures. The mechanical stabilization of different soils is evaluated by adding varying proportions of marble dust (10, 20, 30 percent) of Penjwen, Said Sadiq and Pirmam marble waste powder) to expansive soil. Shear strength and consolidation parameters, such as void ratio, compression index, and sample swelling index, were determined as basic properties. The marble dust is obtained from the cutting and grinding of real marble from the Erbil marble factory in the experimental program. The addition of marble dust decreases the swelling percentage, with an increase in the percentage of marble powder in swelling soils. It is concluded that the swelling in Bastora soil is more than that of Erbil Airport soil, based on the swelling index studies.
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Zhao, Tian Yu, Hu Yuan Zhang i Chen Xiang Yu. "Soil-Water Characteristics of Saline Soil in Northwest China". Advanced Materials Research 487 (marzec 2012): 548–52. http://dx.doi.org/10.4028/www.scientific.net/amr.487.548.
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Geotechnical engineers have become increasingly aware of salt damages caused by water-salt migration.The soil water characteristic curve (SWCC) is a very important tool for determining the engineering properties of unsaturated soil. Using pressure plate extractors, This paper carried out a research on soil-water characteristics of saline soil in northwest China. Then, The relationship between matrix suction and water content was analyzed, the unsaturated hydraulic conductivity in different water content was calculated through predicting model of Van Genuchten(1980). Based on the measurement and calculation, the correlation between unsaturated hydraulic conductivity and water content was established. Research results show that unsaturated hydraulic conductivity of saline soil decreases in non-linear trend with the water content reducing, while it decline linearly by a certain specific rate with the matrix suction increasing at a high-suction section (100kpa ~ 100000kpa) in double logarithmic coordinates.
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Pham, Hung Q., i Delwyn G. Fredlund. "Equations for the entire soil-water characteristic curve of a volume change soil". Canadian Geotechnical Journal 45, nr 4 (kwiecień 2008): 443–53. http://dx.doi.org/10.1139/t07-117.
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Numerous curve-fitting equations have been proposed for soil-water characteristic curves. While these equations have been of considerable value in geotechnical and geoenvironmental engineering, the equations are not able to adequately fit gravimetric soil-water characteristic curve data over the entire range of soil suction for a soil that changes volume when suction is changed. Two new equations for the soil-water characteristic curve are presented in this paper. One equation has curve-fitting parameters that bear a meaningful relationship to conventional physical soil properties (e.g., air-entry value and residual soil suction), but the equation is somewhat complex. The equation is particularly useful for sensitivity type studies when undertaking computer modeling. The other equation is relatively simple to use and is developed as a conventional curve-fitting equation. The two equations are used to best-fit several soil datasets. Both equations perform well and can be used in research and engineering practice to define the gravimetric water content versus soil suction relationship for a soil exhibiting volume change.
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Yang, Hong, H. Rahardjo, E. C. Leong i D. G. Fredlund. "A study of infiltration on three sand capillary barriers". Canadian Geotechnical Journal 41, nr 4 (1.08.2004): 629–43. http://dx.doi.org/10.1139/t04-021.
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The capillary barrier effect was investigated by conducting infiltration tests on three soil columns of fine sand over medium sand, medium sand over gravelly sand, and fine sand over gravelly sand. The barrier effect was verified in the underlying layer of coarser material, and the water-entry values of the coarser layers were confirmed to be nearly equal to the residual matric suctions of the soils. The coarser layer of gravelly sand, which had a lower water-entry value, was more effective in forming a barrier than the coarser layer of medium sand, which had a higher water-entry value. When the capillary barrier was comprised of a coarser layer of gravelly sand, there was more water stored in the finer layer at the end of the drying stage than when the capillary barrier was comprised of a coarser layer of medium sand. Non-equilibrium static conditions of pore-water pressure profiles were observed in the three soil columns, and a generalized ultimate pore-water pressure profile of a capillary barrier system was proposed. In addition, the final volumetric water contents versus matric suctions of the soils as measured from the soil columns were reasonably consistent with the soil-water characteristic curves (SWCCs) of the soils, suggesting that the drying SWCC of a soil could also be obtained from the drying process in a soil column (or a capillary open tube). The drying SWCC could be established from measurements in the soil column up to a height corresponding to two times the residual matric suction head of the soil.Key words: capillary barrier, soil column, soil-water characteristic curve, pore-water pressure, water content, matric suction.
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Tsybulka, Mikalai M. "Water erosion of soils of agricultural lands in Belarus". Journal of the Belarusian State University. Ecology., nr 3 (30.09.2022): 102–9. http://dx.doi.org/10.46646/2521-683x/2022-3-102-109.
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The results of the analysis of the spread of eroded soils on agricultural lands, the quantitative assessment of factors determining the manifestation of water-erosion processes in the northern and central soil-ecological provinces of Belarus are presented. On the territory of Belarus, water erosion is caused by the runoff of meltwater and heavy rainfall, manifested on the slopes in the form of washing away the upper part of the soil cover or in the form of erosion in depth. Eroded soils are concentrated mainly on arable land. Of the total area of soils subject to water erosion, slightly washed soils predominate (57 %), medium-washed soils occupy 25 %, strongly washed soils - 4 %. Water erosion prevails in the northern and central parts of the republic, so the largest areas of washed away soils are concentrated in the Vitebsk, Mogilev and Minsk regions. Significant fluctuations in the areas of eroded soils are observed in administrative districts. The largest areas of them as part of arable land (>20 %) are in Novogrudok, Volozhinsky, Korelichsky, Goretsky and Mstislavsky districts, significant areas (15-20 %) are in the areas of the hilly-moraine landscape: Braslavsky, Gorodoksky, Lepelsky. In the northern soil-ecological province, the intensity of water-erosion processes is determined primarily by climatic conditions, secondly by geomorphological, and thirdly by soil conditions. In the central province, the soil-anthropogenic factor has a higher contribution. Therefore, in the northern province, agrotechnical techniques aimed at regulating surface runoff are a priority in choosing anti-erosion measures, in the central province - the formation of a balanced structure of crops and the introduction of soil-protective crop rotations.
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Chen, Yulong. "Soil–Water Retention Curves Derived as a Function of Soil Dry Density". GeoHazards 1, nr 1 (27.08.2018): 3–19. http://dx.doi.org/10.3390/geohazards1010002.
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The soil–water retention curves (SWRC) of soil plays a key role in unsaturated soil mechanics, which is a relatively new field of study having wide applications particularly in geotechnical and geo-environmental engineering. SWRCs were used to evaluate the ability of unsaturated soils to attract water with various water contents and matric suctions. Drying and wetting SWRCs for a sandy soil with different dry densities were studied in a laboratory. Proton nuclear magnetic resonance, image processing technology, and mercury intrusion porosimetry were used to characterize the microscopic mechanisms of pore size distribution in the soil. Soil–water retention in the soil samples was strongly dependent on the dry density. With zero matric suction, soil samples with a higher dry density had a lower initial volumetric water content. Volumetric water content changed at a slower rate when values of matric suction increased in soils with a higher dry density. Soil samples had residual matric suction and a larger air-entry value with a smaller slope of the SWRC when they had a higher density. Dry density change is mainly responsible for the large pores. The number of large pores decreased as dry density increased. As the dry density increased, the area of macropores occupying the largest portion decreased, while the area of mesopores and micropores increased. Minipores accounted for the smallest proportion of total area and they were nearly constant. The proportion of large diameter pores decreased relative to pores with small diameters in the tested soils. The total pore volume was lower for soil specimens that had larger dry densities, as compared to relatively loose specimens. There was hysteresis between the drying and wetting curves for all soil samples. Hysteresis decreased as the dry density of the soil increased. The different liquid–solid contact angle was the main factor causing hysteresis of SWRC.
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Li, J. H., L. M. Zhang i X. Li. "Soil-water characteristic curve and permeability function for unsaturated cracked soil". Canadian Geotechnical Journal 48, nr 7 (lipiec 2011): 1010–31. http://dx.doi.org/10.1139/t11-027.
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Cracks are widely present in natural and engineered soils. As water infiltration into a cracked soil often starts from unsaturated conditions, the soil-water characteristic curve (SWCC) and permeability function for the cracked soil are required when conducting seepage analysis. This paper presents a method to predict the SWCC and permeability function for cracked soil considering crack volume changes during drying–wetting processes. The cracked soil is viewed as an overlapping continuum of a crack network system and a soil matrix system. The pore-size distributions for the two pore systems at a particular state can be determined and used to estimate the SWCCs and permeability functions. The estimated SWCCs and permeability functions for the two pore systems can be combined to give the SWCC and the permeability function for the cracked soil at that state. Then, the SWCC and permeability function for the cracked soil at different states along a crack development path can be obtained and combined to give the SWCC or permeability function for the cracked soil considering crack volume changes. Examples are presented to illustrate the prediction of the SWCCs and permeability functions for a cracked soil along five crack development paths.
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Dong, Shaoyang, Yuan Guo i Xiong (Bill) Yu. "Method for Quick Prediction of Hydraulic Conductivity and Soil-Water Retention of Unsaturated Soils". Transportation Research Record: Journal of the Transportation Research Board 2672, nr 52 (28.09.2018): 108–17. http://dx.doi.org/10.1177/0361198118798486.
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Hydraulic conductivity and soil-water retention are two critical soil properties describing the fluid flow in unsaturated soils. Existing experimental procedures tend to be time consuming and labor intensive. This paper describes a heuristic approach that combines a limited number of experimental measurements with a computational model with random finite element to significantly accelerate the process. A microstructure-based model is established to describe unsaturated soils with distribution of phases based on their respective volumetric contents. The model is converted into a finite element model, in which the intrinsic hydraulic properties of each phase (soil particle, water, and air) are applied based on the microscopic structures. The bulk hydraulic properties are then determined based on discharge rate using Darcy’s law. The intrinsic permeability of each phase of soil is first calibrated from soil measured under dry and saturated conditions, which is then used to predict the hydraulic conductivities at different extents of saturation. The results match the experimental data closely. Mualem’s equation is applied to fit the pore size parameter based on the hydraulic conductivity. From these, the soil-water characteristic curve is predicted from van Genuchten’s equation. The simulation results are compared with the experimental results from documented studies, and excellent agreements were observed. Overall, this study provides a new modeling-based approach to predict the hydraulic conductivity function and soil-water characteristic curve of unsaturated soils based on measurement at complete dry or completely saturated conditions. An efficient way to measure these critical unsaturated soil properties will be of benefit in introducing unsaturated soil mechanics into engineering practice.
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Zheng, Xian Chun, Fang Zhao i Si Zhong Sun. "Study on the Tests of Soil-Water Characteristic Curves of Unsaturated Soil". Applied Mechanics and Materials 353-356 (sierpień 2013): 16–19. http://dx.doi.org/10.4028/www.scientific.net/amm.353-356.16.
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Soil-water characteristic curve is used to describe the matrix suction and water content of the curve of the relationship between volume, according to the soil-water characteristic curve can be deduced the unsaturated soil shear strength, permeability coefficient, etc., this paper gives the different initial water content and different types of soil, soil-water characteristic curve for practical engineering foundation reinforcement to provide reference.