Effect of Time History on Long-Term Deformation of Gypseous Soils

Fattah, Mohammed Y.; Al-Shakarchi, Yousif J.; AL-Numani, Huda N. T.

doi:10.2478/sgem-2022-0011

Cited by 8 publications

(2 citation statements)

References 14 publications

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“…According to Fattah et al [42], an increase in gypsum concentration leads to a reduction in the shear strength parameters (φ and c). The presence of gypsum in soil, especially when not exposed to water, has minimal impact on its behavior compared to soils without gypsum or when subjected to applied stresses.…”

Section: Static Triaxial Test (Cu-test)mentioning

confidence: 99%

Studying Characteristics and Strength of the Unsaturated Gypseous Soil with Various Saturation Degrees

Abood,

Fattah,

Al-Adili

2023

ETJ

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Tests on gypseous soil include standard Proctor compactions and consolidated undrained triaxial compression.• The soil was either natural, unsaturated at degrees of saturation (30%, 60%, and 80%), or fully saturated. • Increasing the humidity of the gypseous soil at saturation degrees causes a decline in the internal friction angle. • The soil cohesion for effective and total stress increased with gypseous soil moisture up to (60%) saturation degree.The main objective of this study is to determine the appropriateness of unsaturated gypseous soil as a subgrade layer for carrying foundations. A comprehensive laboratory testing program was implemented to investigate the geotechnical characteristics and behavior of unsaturated gypseous soil. Tests that are physical included specific gravity, classification tests, relative density, Proctor compactions, single and double oedometer collapse potential, and static triaxial compression (CU-test). Chemical testing, Scanning Electron Microscopy (SEM), and Electronic Dissipation x-ray Scanning (EDS) analyses were also carried out.The tests were performed for samples prepared at 70% relative density of the natural gypseous soil. Tests are performed on the natural, unsaturated at degrees of saturation (30%, 60%, and 80%) and fully saturated gypseous soil to investigate the gypseous soil behaviors. In both single and double oedometer testing, it was discovered that the degree of specimen collapse is (Moderate) at 70% relative density, with a collapse index value ranging from (4%). The angle of internal friction for both total and effective stresses (φ' and φ) decreases as the moisture content of the gypseous soil increases at all saturation levels. In contrast, it was found that the strength of soil cohesion for both total and effective stresses (c' and c) increased with increasing gypseous soil moisture up to saturation (60%), which led to a rise in soil shear strength. The reduction value ranged from (38.50° to 7°) in respect of effective stresses and between (34.50° and 7°) with respect to total stresses. Effective stress increase varied from (10.0 -26.0 kPa), and total stress increase ranged from (12.50 -28.0 kPa). Then the strength started gradually decreasing at the saturation degrees 80 and 100%, respectively. As a result, the shear strength of the soil decreases with the value of reduction ranging from (20.0 -11.50 kPa) for effective stresses and (21.50 -11.50 kPa) for total stresses.

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Section: Static Triaxial Test (Cu-test)mentioning

confidence: 99%

Studying Characteristics and Strength of the Unsaturated Gypseous Soil with Various Saturation Degrees

Abood,

Fattah,

Al-Adili

2023

ETJ

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“…The amount and kind of gypsum present in the soil, the ambient circumstances, and the type of engineering challenge under consideration all influence the gypsum effect. [8]. When dry, it is highly robust and has good characteristics, but as moisture content increases, it gradually weakens.…”

Section: Introductionmentioning

confidence: 99%

Assessment of Salts and Organic Matter of Umm Qasser Soil, Basrah

Daham

2022

sjpas

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This study was conducted in Umm Qasser, which is located in Al-Zubair district, in Basra. The research focused on studying the soil content of sulfates, chlorides, and organic matter. The research aims to measure the concentrations of salts and organic matter, compare them with standard specifications, and to know whether these concentrations affect the engineering behavior of the soil or not, and chemical tests were carried out for them. The results show that the average of sulfate is 0.55%, gypsum is 4.75%, chloride is 0.35% and organic matter is 4.28%. The study shows that the soil content of chlorides, organic matter, and Gypsum were within the effective limits on engineering behavior of soil except for other forms of sulfates, and the study shows that the fluctuation of the soil content of salts, and organic matter from one site to another, and at different depths is subject to change with time due to its influence by geological and environmental factors at the study area.

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