scholarly journals Variability of Bimodal Soil-Water Characteristic Curves under Different Confining Pressures

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Achmad Syarifudin ◽  
Alfrendo Satyanaga
Keyword(s):  
Soil Water ◽  
Characteristic Curve ◽  
Confining Pressure ◽  
Dual Porosity ◽  
Residual Soils ◽  
Triaxial Apparatus ◽  
Confining Pressures ◽  
Mathematical Equations ◽  
Wetting Curve ◽  
Unsaturated Zones

Soils with two subcurves of Soil-Water Characteristic Curve (SWCC) (dual porosity soils) might be found within various residual soils. Soils located in different depths have different confining pressure. Residual soils are found in the unsaturated zones due to the deep groundwater table. There is a linear correlation between the hydraulic properties of the soil in the unsaturated area and that of its unsaturated properties. This study aims to examine the influence of the confining pressure towards the SWCC of dual porosity soil. The scope of this study involves measurements of the drying and wetting SWCC using Tempe cells, pressure plates, and an advanced triaxial apparatus. In this study, the mathematical equations were developed to explain the effect of confining pressure on SWCC. The experimental results indicated that the dual porosity soil exhibits bimodal characteristics for the drying curve of SWCC and it exhibits unimodal characteristics for the wetting curve of SWCC. As the confining pressure increases, the air entry values, the inflection points, and the standard deviation of drying SWCC increase. In addition, the hysteresis of SWCC is becoming smaller with the increasing confining pressure.

The Trial Research of Soil-Water Characteristic Curves of Unsaturated Soil and its Engineering Application

2012 ◽  
Vol 170-173 ◽  
pp. 3050-3053
Author(s):  
Cui Ran Liu ◽  
Jin Jun Guo
Keyword(s):  
Soil Water ◽  
Unsaturated Soil ◽  
Permeability Coefficient ◽  
Characteristic Curve ◽  
Engineering Application ◽  
Engineering Properties ◽  
Confining Pressures ◽  
Soil Water Characteristic Curves ◽  
Matrix Suction ◽  
Water Contents

With the improved triaxial equipment, the tests of research of the relationships between matrix suction and water content are performed And based on the test data, the curves between matrix suction and water contents under different confining pressures are drawn and the change rule between them are analyzed. And then the function between them is simulated out. Through the soil-water characteristic curve, the permeability coefficient of unsaturated soil can be calculated and the shear strength of unsaturated soil can be predicted. These results are important to research the engineering properties of unsaturated soil.

Triaxial Shrinkages Tests of Unsaturated Compacted Clay

2011 ◽  
Vol 194-196 ◽  
pp. 1041-1044
Author(s):  
Dong Lin Wang
Keyword(s):  
Soil Water ◽  
Characteristic Curve ◽  
Experimental Tests ◽  
Degree Of Saturation ◽  
Mean Stress ◽  
Compacted Clay ◽  
Soil Water Characteristic Curve ◽  
Triaxial Apparatus ◽  
Soil Triaxial Apparatus ◽  
Shrinkage Coefficient

In this paper, The GDS unsaturated soil triaxial apparatus are employed for experimental tests to obtain the main characteristics of the drying paths for compacted clay. In order to study the soil water characteristic curve and shrinkage coefficient under deferent net mean stress. The results show that shrinkage index and the soil-water characteristic curve are dependent on net mean stress. At a given matric suction, with the increase of net mean stress, the void ratio and water content of soil sample is decrease, but the degree of saturation is increased.

Experimental Study on Soil Water Characteristic Curve of Compacted Unsaturated Soil

2010 ◽  
Vol 168-170 ◽  
pp. 1285-1288
Author(s):  
Dong Lin Wang
Keyword(s):  
Soil Water ◽  
Influencing Factors ◽  
Unsaturated Soils ◽  
Stress Condition ◽  
Characteristic Curve ◽  
External Stress ◽  
Method Of Least Squares ◽  
Soil Water Characteristic Curve ◽  
Triaxial Apparatus ◽  
Soil Water Characteristic Curves

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.

scholarly journals Influence of drying–wetting cycles on soil-water characteristic curve of undisturbed granite residual soils and microstructure mechanism by nuclear magnetic resonance (NMR) spin-spin relaxation time (T2) relaxometry

2018 ◽  
Vol 55 (2) ◽  
pp. 208-216 ◽  
Author(s):  
Lingwei Kong ◽  
Hossain Md. Sayem ◽  
Huihui Tian
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Relaxation Time ◽  
Magnetic Resonance ◽  
Size Distribution ◽  
Soil Water ◽  
Spin Relaxation ◽  
Characteristic Curve ◽  
Spin Relaxation Time ◽  
Residual Soils ◽  
Soil Water Characteristic Curve

Due to the formational environment and climatic variability, granite residual soils with grain-size distribution ranging from gravel to clay undergo multiple drying–wetting cycles. The influences of multiple drying–wetting cycles on the soil-water characteristic curve (SWCC) and pore-size distribution (POSD) of undisturbed granite residual soils are investigated using the pressure plate test and nuclear magnetic resonance (NMR) spin-spin relaxation time (T2) distribution measurement, respectively. Results show that the water-retention capacity and air-entry value decrease and pores become more uniform with increasing drying–wetting cycles. After four drying–wetting cycles, the soil reaches a nearly constant state. The POSD change of multiple drying–wetting cycle samples is consistent with the SWCC of the soils. Furthermore, a modified van Genuchten model in terms of cumulative pore volume is used to obtain the best-fit POSD of the drying–wetting cycle samples. The shape and changing tendency of both curves of SWCC and POSD are quite similar and achieved a better correlation. It can be concluded that the SWCC is strongly dependent on the POSD of the soil and NMR T2 relaxometry can be used as an alternative to the assessment of microstructural variation of residual soils subjected to the periodic drying and wetting process.

scholarly journals Soil-Water Characteristic Curve of Residual Soil from a Flysch Rock Mass

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-15 ◽  
Author(s):  
Josip Peranić ◽  
Željko Arbanas ◽  
Sabatino Cuomo ◽  
Matej Maček
Keyword(s):  
Rock Mass ◽  
Soil Water ◽  
Characteristic Curve ◽  
Detailed Examination ◽  
Residual Soil ◽  
Residual Soils ◽  
Infiltration Process ◽  
Soil Water Characteristic Curve ◽  
Wide Range ◽  
Flysch Rock Mass

Depending on the nature of the material and suction range, laboratory measurements of the soil-water characteristic curve (SWCC) can be time-consuming and expensive, especially for residual soils, in which a wide range of particle sizes and soil structures typically results in SWCCs that cover a wide range of suction. Investigations of the SWCCs of residual soil from flysch rock masses are rare, and so far, no results were presented in the literature which were obtained by performing measurements on undisturbed specimens. In this paper, a detailed examination of water retention characteristics is performed for a specific type of residual soil (CL) formed by the weathering of a flysch rock mass. Measurements performed by using different techniques and devices on intact specimens were successfully combined to obtain the SWCC during both drying and wetting processes, under different stress conditions, and from saturated to air-dried conditions. Used procedures are suitable for the determination of SWCCs of soils that undergo volume changes during the drying or the wetting process, since instantaneous volumetric water content can be determined. Results presented in this paper can be used to assess the influence of desaturation of the residual soil covering flysch slopes during dry summer periods by providing key-in material properties required to analyze the transient rainfall infiltration process.

Predicting Reservoir Pressure with Soil-Water Characteristic Curve

2014 ◽  
Vol 1073-1076 ◽  
pp. 2215-2218
Author(s):  
Xiong Wei Li ◽  
Yong Wang ◽  
Xiao Shu Jiang
Keyword(s):  
Water Retention ◽  
Characteristic Curve ◽  
Confining Pressure ◽  
Stress Path ◽  
Water Retention Capacity ◽  
Reservoir Pressure ◽  
Gas Reservoir ◽  
Retention Capacity ◽  
Unsaturated Sand ◽  
Confining Pressures

Experiment study on shallow gassy unsaturated sand under different confining pressure with GDS triaxial system's 4D stress path module is carried out. Different SWCC shapes under different confining pressures are analyzed. The results show that unsaturated sand's water retention capacity declines gradually with confining pressure infliction and accretion. Finally, shallow gassy sand's gas reservoir pressure characteristics with SWCC are analyzed and forecast, and it's conservative if the same thing is done based on SWCC without confining pressure.

Evaluating dual porosity of pelletized diatomaceous earth using bimodal soil-water characteristic curve functions

2001 ◽  
Vol 38 (1) ◽  
pp. 53-66 ◽  
Author(s):  
Craig A Burger ◽  
Charles D Shackelford
Keyword(s):  
Soil Water ◽  
Diatomaceous Earth ◽  
Pore Space ◽  
Characteristic Curve ◽  
Coarse Grained ◽  
Dual Porosity ◽  
Scanning Electron Micrographs ◽  
Characteristic Curves ◽  
Soil Water Characteristic Curve ◽  
Soil Water Characteristic Curves

Soil-water characteristic curve data for specimens containing either ~1 mm or ~2 mm diameter pellets of processed diatomaceous earth are measured using a variety of methods (Tempe cell, pressure plate, filter paper, and chilled-mirror psychrometer). The measured soil-water characteristic curve data are bimodal, reflecting both the microscopic porosity region within the individual pellets, or intrapellet porosity, and the macroscopic porosity region between the pellets, or interpellet porosity. The bimodal distributions are consistent with scanning electron micrographs that show the existence of microscopic pores within each pellet, and the relatively high total porosities (0.725 and 0.764) for the coarse-grained diatomaceous earth specimens. The measured soil-water characteristic curve data are fit with modified forms of the Brooks–Corey, van Genuchten, and Fredlund–Xing soil-water characteristic curve functions to account for the bimodal shapes of the measured data. The average microscopic porosities resulting from the curve fits represent 45.0 and 47.9% of the total porosities for the two diatomaceous earth materials. These percentages of microscopic pore space are consistent with the product literature value of approximately 50% for the same materials based on mercury intrusion porosimetry. Thus, the results illustrate the application of bimodal soil-water characteristic curve functions for determining the microscopic and macroscopic portions of the total porosity of dual-porosity media, such as pelletized diatomaceous earth.Key words: bimodal soil-water characteristic curves, diatomaceous earth, dual porosity, macroporosity, microporosity, soil-water characteristic curves (SWCC), soil suction.

Determination and Compare Analysis for Soil Water Characteristic Curve Model in Planting Soil in Saline Region of Tianjin

2010 ◽  
Vol 12 (3) ◽  
pp. 336-341
Author(s):  
Fei CAI ◽  
Xiaohou SHAO ◽  
Zhenyu WANG ◽  
Mingyong HUANG ◽  
Yaming ZHAI ◽  
...  
Keyword(s):  
Soil Water ◽  
Characteristic Curve ◽  
Soil Water Characteristic Curve ◽  
Curve Model ◽  
Compare Analysis
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