Physical changes in seedbed material resulting from the application of dissolved gypsum

Soil Research ◽  
1966 ◽  
Vol 4 (1) ◽  
pp. 69 ◽  
Author(s):  
DR Scotter ◽  
J Loveday
Keyword(s):  
Hydraulic Conductivity ◽  
Water Retention ◽  
Clay Soil ◽  
Physical Changes

The effect of an initial irrigation of gypsum solution, as compared with water, on water retention and transmission in a seedbed loam and clay and the subsequent changes in porosity during drying have been studied. A marked increase in hydraulic conductivity, particularly in the clay soil, and concomitant increases in total and air-filled porosity at all matric potentials, from near saturation to oven dry, were measured. The data provide an explanation of the earlier observation that improved emergence resulting from gypsum treatment was associated with the maintenance of higher matric potentials in the surface 4 in. of soil for longer periods after irrigation.

MEASURING HYDRAULIC CONDUCTIVITY IN A CRACKING CLAY SOIL USING THE GUELPH PERMEAMETER

1999 ◽  
Vol 42 (4) ◽  
pp. 957-964 ◽  
Author(s):  
V. Bagarello ◽  
M. Iovino ◽  
W. D. Reynolds
Keyword(s):  
Hydraulic Conductivity ◽  
Clay Soil ◽  
Guelph Permeameter

scholarly journals Reductions in root hydraulic conductivity in response to clay soil and treated waste water are related to PIPs down-regulation in Citrus

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Indira Paudel ◽  
Shabtai Cohen ◽  
Lyudmila Shlizerman ◽  
Amit K. Jaiswal ◽  
Avi Shaviv ◽  
...  
Keyword(s):  
Waste Water ◽  
Hydraulic Conductivity ◽  
Clay Soil ◽  
Down Regulation ◽  
Root Hydraulic Conductivity

Method for Quick Prediction of Hydraulic Conductivity and Soil-Water Retention of Unsaturated Soils

2018 ◽  
Vol 2672 (52) ◽  
pp. 108-117 ◽  
Author(s):  
Shaoyang Dong ◽  
Yuan Guo ◽  
Xiong (Bill) Yu
Keyword(s):  
Finite Element ◽  
Hydraulic Conductivity ◽  
Soil Properties ◽  
Soil Water ◽  
Unsaturated Soil ◽  
Unsaturated Soils ◽  
Hydraulic Properties ◽  
Water Retention ◽  
Characteristic Curve ◽  
Soil Water Retention

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.

scholarly journals A numerical study on the effect of salinity on stability of an unsaturated railway embankment under rainfall

2020 ◽  
Vol 195 ◽  
pp. 01004
Author(s):  
Ali Kolahdooz ◽  
Hamed Sadeghi ◽  
Mohammad Mehdi Ahmadi
Keyword(s):  
Hydraulic Conductivity ◽  
Soil Water ◽  
Water Retention ◽  
Numerical Study ◽  
Water Retention Curve ◽  
Soil Water Retention Curve ◽  
Soil Water Retention ◽  
Unsaturated Hydraulic Conductivity ◽  
Influence Of Water ◽  
Dispersive Soils

Dispersive soils, as one of the main categories of problematic soils, can be found in some parts of the earth, such as the eastern-south of Iran, nearby the Gulf of Oman. One of the most important factors enhancing the dispersive potential is the existence of dissolved salts in the soil water. The main objective of this study is to explore the influence of water salinity on the instability of a railway embankment due to rainfall infiltration. In order to achieve this goal, the embankment resting on a dispersive stratum is numerically modeled and subjected to transient infiltration flow. The effect of dispersion is simplified through variations in the soil-water retention curve with salinity. The measured water retention curves revealed that by omitting the natural salinity in the soil-water, the retention capability of the soil decreases; therefore, the unsaturated hydraulic conductivity of the soil stratum will significantly decline. According to the extensive decrease in the hydraulic conductivity of the desalinated materials, the rainfall cannot infiltrate in the embankment and the rainfall mostly runs off. However, in the saline embankment, the infiltration decreases the soil suction; and consequently, the factor of safety of the railway embankment decreases.

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