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Acta Geotechnica - Root depth and leaf area ratio are two important features of a plant and exhibit a coupled relation. Assessing their coupled effects on induced soil suction is essential for... 相似文献
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Ankit Garg Akhil Garg K. Tai S. Sreedeep 《Geotechnical and Geological Engineering》2014,32(4):765-772
Soil–water characteristic curve (SWCC) is one of the input components required for conducting the transient seepage analysis in unsaturated soil for estimating pore water pressure (PWP). SWCC is usually defined by saturated volumetric water content (θs), residual water content (RWC) and air entry value (AEV). Mathematical model of PWP could be useful to unearth the important SWCC components and the physics behind it. Based on authors’ knowledge, rarely any mathematical models describing the relationship between PWP and SWCC components are found. In the present work, an evolutionary approach, namely, multi-gene genetic programming (MGGP) has been applied to formulate the relationship between the PWP profile along soil depth and input variables for SWCC (θs, RWC and AEV) for a given duration of ponding. The PWP predicted using the MGGP model has been compared with those generated using finite element simulations. The results indicate that the MGGP model is able to extrapolate the PWP satisfactory along the soil depth for a given set of boundary conditions. Based on the given AEV and saturated water content, the PWP along the depth can be determined from the newly developed MGGP model, which will be useful for design and analysis of slopes and landfill covers. 相似文献
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Vikas K. S. Thakur S. Sreedeep Devendra N. Singh 《Geotechnical and Geological Engineering》2006,24(3):565-578
A Dewpoint PotentiaMeter (WP4) was used to measure suction of two fine-grained soils: a locally available silty soil and commercially
available white clay, rapidly. Using these results, efforts were made to check the suitability and efficiency of various fitting
functions, for defining the soil–water characteristic curve, SWCC, for high suction ranges (0–80 MPa). In addition to this,
a knowledge-based database SoilVision 3.34 was used to estimate the SWCC using Pedo-transfer functions, PTFs. The study brings
out that the Fredlund et al. [1997, Proceedings of the 3rd Symposium on Unsaturated Soil, Rio de Janeiro, Brazil, pp. 13–23] PTF yields the best estimate of SWCC for fine-grained soils. The influence of the soil
type and dry unit weight, on suction and the SWCC fitting parameters, have also been studied. 相似文献
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Deka Abhijit Gupt Chandra B. Sekharan Sreedeep 《Geotechnical and Geological Engineering》2021,39(5):3889-3901
Sand-Bentonite mixtures are used in landfill liner application in appropriate proportions. However, effort has been made to replace the sand by some waste materials like fly ash without compromising the required properties for liner construction. In recent years, many studies were carried out to determine the suitability of different fly ashes for using with bentonite based on different geotechnical parameters. On the other hand, limited studies were found in determining the unsaturated characteristics i.e. Water Retention Characteristics Curve (WRCC) of fly ash-bentonite mixes. The determination of WRCC in case of bentonite is very complexed compared to other types of clay soil due to its high shrinkage and swelling characteristics upon drying and wetting. In this study, a combined shrinkage and suction measurement was carried out in fly ash-bentonite mixes to accurately represent the WRCC under drying condition only. The shrinkage measurement was carried out using balloon method and suction measurement was carried out with the help of WP4 dew point potentiameter device. Both the shrinkage and suction results were finally used to obtain the WRCC for the different mixes. Further, the study on the variability of WRCCs for the different mixes indicates that WRCC can be represented by a generalized plot with 20% variation.
相似文献5.
With rapid advancements in technology globally, the use of plastics such as polyethylene bags, bottles etc. is also increasing. The disposal of thrown away wastes pose a serious challenge since most of the plastic wastes are non-biodegradable and unfit for incineration as they emit harmful gases. Soil stabilization improves the engineering properties of weak soils by controlled compaction or adding stabilizers like cement, lime etc. but these additives also have become expensive in recent years. This paper presents a detailed study on the behavior and use of waste plastic in soil improvement. Experimental investigation on reinforced plastic soil results showed that, plastic can be used as an effective stabilizer so as to encounter waste disposal problem as well as an economical solution for stabilizing weak soils. Plastic reinforced soil behaves like a fiber reinforced soil. This study involves the investigation of the effect of plastic bottle strips on silty sand for which a series of compaction, direct shear and California bearing ratio (CBR) tests have been performed with varying percentages of plastic strips and also with different aspect ratios in terms of size. The results reflect that there is significant increment in maximum dry unit weight, Shear Strength Parameters and CBR value with plastic reinforcement in soil. The quantum of improvement in the soil properties depends on type of soil, plastic content and size of strip. It is observed from the study that, improvement in engineering properties of silty sand is achieved at 0.4% plastic content with strip size of (15 mm?×?15 mm). 相似文献
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Tensiometer is one of the most popular and simple instrument for in situ and laboratory measurement of negative pressure or suction in soils. Such measurements in the top soil or root zone are useful for automated optimized irrigation scheduling for different vegetation. The top soil accommodates various salts/contaminants whose main source is storm water runoff, irrigation water and application of crop fertilizers. These salts accumulate in the soil due to evaporation. It is an established fact that tensiometer measures only soil matric suction with the help of a ceramic interface. It is believed that osmotic effect of salts present in the soil does not influence tensiometer measurements. However, there is no systematic experimental verification in the literature to understand the influence of salt laden soil on tensiometer measurements. It needs to be ascertained that the pore size of the tensiometer ceramic will not exhibit semi-permeable membrane characteristics leading to osmotic effect. Such verification is important as it would influence the irrigation scheduling of crops. It is also of interest to know whether the osmotic suction (due to the salts) would increase the water retention characteristics and hence the irrigation requirement. If so, then the tensiometer based irrigation scheduling would be an underestimate of the actual irrigation requirement of crops. To investigate these issues, the present study has performed controlled laboratory suction measurements using tensiometer in a locally available soil, contaminated with known concentration of inorganic salt solution. The total suction of the same salt laden soil has been measured using the WP4 dew point potentiameter technique. The results indicate negligible influence of salts present in the soil on tensiometer measurements. The study demonstrates the incapability of tensiometer to assess the osmotic component of salt present in the soil. This would result in the under prediction of water retention and hence irrigation requirement of the soil. 相似文献
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Soil suction constitutes of the matric suction and the osmotic suction. Several studies have been conducted and reported by
researchers that reveal the importance of the matric suction on unsaturated soil properties. However, not many efforts have
been made to develop methodologies that can be employed for measuring osmotic suction of the soil and to understand its influence
on unsaturated soil properties. With this in view, efforts were made to utilize the results of the pressure membrane extractor
(PME) and the dewpoint potentiameter (WP4), which measure matric and total suction of the soil, respectively. Details of the
methodology developed to achieve this are presented in this technical note. 相似文献
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