The Experts below are selected from a list of 8091 Experts worldwide ranked by ideXlab platform
Andreas Bieberstein - One of the best experts on this subject based on the ideXlab platform.
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determination of the soil Water Retention Curve and the unsaturated hydraulic conductivity from the particle size distribution
2nd International Conference on Mechanics of Unsaturated Soils, 2007Co-Authors: Alexander Scheuermann, Andreas BiebersteinAbstract:Because of the complexity of the metrological determination of the soil Water Retention Curve (SWRC), so-called pedotransfer functions (PTF) have been developed for several years. Mostly these PTF are based on a more or less simple regression analysis using a limited set of data. In such methods the SWRC is predicted with data on the amount of soil components sometimes supplemented by values regarding the density or the amount of organic materials. Only few PTF deal directly with the particle size distribution. In many cases empirical factors are necessary to obtain a prediction for the Water Retention Curve. A new method for determining the soil-hydraulic properties using the pore constriction distribution of a soil has been developed, whereby the pore constriction distribution is derived from the particle size distribution depending on the density of the soil. The contribution will present the new pedotransfer method and shows results in comparison to experimental investigations.
B Witkowskawalczak - One of the best experts on this subject based on the ideXlab platform.
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complete characterization of pore size distribution of tilled and orchard soil using Water Retention Curve mercury porosimetry nitrogen adsorption and Water desorption methods
Geoderma, 2006Co-Authors: M Hajnos, Z Sokolowska, Jerzy Lipiec, Ryszard świeboda, B WitkowskawalczakAbstract:Abstract Pore size distribution (PSD) affects numerous soil functions and root growth. The PSD is largely influenced by soil management practices. We have compared the PSD in a wide pore size range of conventionally tilled (CT) and orchard (OR) loamy soil, determined by different methods. Water Retention Curve, mercury intrusion porosimetry, nitrogen adsorption isotherm and Water desorption isotherm were used to quantify the PSD for equivalent pore radii > 50 to 0.1 μm, 7.5 to 0.0037 μm, 0.1 to 0.001 μm and 0.05 to 0.001 μm, respectively. Soil samples were taken from 0–10, 10–20, 20–30 and 30–40 cm depths. The PSD was presented in the form of cumulative pore volume and logarithmically differential pore volume Curves with respect to the pore radius. The cumulative Curve showed that at depth 0–10 cm the volume of larger pores (> 45 μm radius) was greater under CT soil than OR. However, in deeper layers up to 40 cm, the concentration of the larger pores was greater and that of smaller pores fewer in OR than CT. As shown by the differential pore Curve, both OR and CT soil exhibited peaks within textural (primary) and secondary (structural) pore systems. The textural peaks of the pore throat radius (0.0017 μm) as determined by the nitrogen adsorption method were of greater magnitude at depths 20–40 cm than 0–20 cm and at depths 20–40 cm they were more defined under CT than OR. The textural peaks of approximately 1 μm radius were more defined on the PSD from the mercury intrusion porosimetry than Water Retention Curve. The structural peaks in pore radius 70–80 μm were of greater magnitude under OR than CT at all depths. The results show that the approach employing four methods is a suitable tool for characterising a wide range of pore radii influenced by soil management practices.
Alexander Scheuermann - One of the best experts on this subject based on the ideXlab platform.
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determination of the soil Water Retention Curve and the unsaturated hydraulic conductivity from the particle size distribution
2nd International Conference on Mechanics of Unsaturated Soils, 2007Co-Authors: Alexander Scheuermann, Andreas BiebersteinAbstract:Because of the complexity of the metrological determination of the soil Water Retention Curve (SWRC), so-called pedotransfer functions (PTF) have been developed for several years. Mostly these PTF are based on a more or less simple regression analysis using a limited set of data. In such methods the SWRC is predicted with data on the amount of soil components sometimes supplemented by values regarding the density or the amount of organic materials. Only few PTF deal directly with the particle size distribution. In many cases empirical factors are necessary to obtain a prediction for the Water Retention Curve. A new method for determining the soil-hydraulic properties using the pore constriction distribution of a soil has been developed, whereby the pore constriction distribution is derived from the particle size distribution depending on the density of the soil. The contribution will present the new pedotransfer method and shows results in comparison to experimental investigations.
Emanuel Birle - One of the best experts on this subject based on the ideXlab platform.
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effect of initial Water content and dry density on the pore structure and the soil Water Retention Curve of compacted clay
2012Co-Authors: Emanuel BirleAbstract:An experimental study was carried out to investigate the influence of the initial Water content and dry density on the structure and the SWRC of compacted clay. The soil structure was studied by MIP. For the determination of the soil-Water Retention Curve suction-controlled oedometer cells and a chilled mirror dew-point hygrometer were used. The paper describes the changes of pore structure due to different initial Water contents and dry densities and its influence on the soil-Water Retention Curve.
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influence of the initial Water content and dry density on the soil Water Retention Curve and the shrinkage behavior of a compacted clay
Acta Geotechnica, 2008Co-Authors: Emanuel Birle, Dirk Heyer, Norbert VogtAbstract:The paper presents the results of an experimental study on the effects of the initial Water content and dry density on the soil–Water Retention Curve and the shrinkage behavior of a compacted Lias-clay. The initial conditions after compaction (initial Water content and initial dry density) have been chosen on the basis of three Proctor tests of different compaction efforts. According to the eight chosen initial conditions clay samples have been compacted statically. The relation between total suction and Water content was determined for the drying path starting from the initial conditions without previous saturation of the specimens. A chilled-mirror dew-point hygrometer was used for the suction measurements. For the investigation of the shrinkage behavior cylindrical specimens were dried to desired Water contents step-by-step without previous saturation. The volume of the specimens was measured by means of a caliper. Based on the test results the influence of different initial conditions on the soil suction and the shrinkage behavior is analyzed. The soil–Water Retention Curves obtained in terms of the gravimetric Water content are independent of the initial dry density. At Water contents above approximately 11–12.5% a strong influence of the compaction Water content is observed. At smaller Water contents, the soil–Water Retention Curve is independent of the compaction Water content. The results of the shrinkage tests show that the influence of the compaction dry density on the shrinkage behavior is negligible. Similar to the drying behavior of saturated samples a primary and a residual drying process could be distinguished. The primary drying process is strongly influenced by the initial Water content. In contrast, the rate of the volume change of the residual drying process is unaffected by the initial Water content.
Pedro Victor Serra Mascarenhas - One of the best experts on this subject based on the ideXlab platform.
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Efficient approach in modeling the shear strength of unsaturated soil using soil Water Retention Curve
Acta Geotechnica, 2021Co-Authors: André Luís Brasil Cavalcante, Pedro Victor Serra MascarenhasAbstract:Currently, there are debates on the relationship between the effective stress and shear strength of unsaturated soils. Thus, it is imperative to present an efficient method that could contribute to the existing knowledge in this aspect while ensuring an easy and fast operation. In this study, a novel approach for modeling the shear strength of unsaturated soils using soil Water Retention Curve (SWRC) is proposed. The method considers a coherent thermodynamic expression of Bishop’s effective stress parameter χ and a physical model of the SWRC that depends only on one parameter. First, an expression for unsaturated effective stress was obtained. The starting point to develop the shear strength equation was then determined. The obtained equation can estimate Bishop’s parameter for unsaturated soil using only the SWRC and the relationship between unsaturated shear strength and soil suction. A sensitivity analysis and comparison with other methods that obtained different parameter expressions were also provided. The results showed that the results obtained from the proposed model fits with experimental data, indicating its applicability in studying the average behavior of unsaturated sands.
