Engineering and Technology Journal

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

Ahmed S. Abood; Mohammed Y. Fattah; Aqeel S. Al-Adili

Articles in Press, Corrected Proof, Available Online from 29 August 2023

https://doi.org/10.30684/etj.2023.140119.1453

Abstract

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 ... Read More ... 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 (f' and f) 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.

Impact of Dam Materials and Hydraulic Properties on Developing the Breaching Dimensions

Mahmood J. Mohamed; Ibtisam R. Karim; Mohammed Y. Fattah

Volume 41, Issue 5 , May 2023, , Page 716-723

https://doi.org/10.30684/etj.2023.138009.1368

Abstract

Dam safety is an important issue as it directly influences environmental and life losses. Embankment material and embankment core are important factors that contribute to determining ... Read More ... Dam safety is an important issue as it directly influences environmental and life losses. Embankment material and embankment core are important factors that contribute to determining the size and hydraulic characteristics of the breach that occurs due to dam failure. The current topic is to present the analysis of the impact of the dam materials properties and hydraulic characteristics on breach dimensions due to overtopping failure using 2D-HEC-RAS software with the aid of RAS-Mapper. The analysis was made by Digital Elevation Model (DEM) conversed to a Triangular Irregular Network (TIN), then the 2D area of the dam was determined and the storage area boundary was calculated. Mosul dam in Iraq, considered one of the big dams that consist of different materials in the core and body, was selected as a case study to simulate the dam breach development due to overtopping failure. Six scenarios of dam failure were carried out for three types of dam materials (dam with corewall, concrete-face dam, and homogeneous zoned fill dam), each with high and medium erodibility. All scenarios were made for the reservoir elevation of 341 m which is considered the probable elevation for failure occurrence. The results showed that the minimum and maximum values of breach width were found to be 542 m and 1118 m, respectively in both cases of concrete-face dam type with a high erodibility and homogeneous zoned fill dam with medium erodibility rate. It has been illustrated that the medium erodibility in each scenario gives a smaller width for a long time, especially in homogeneous zoned fill dam type which is a good indication in engineering design. The analysis of sensitivity was carried out to examine the impact of pool volume at failure on breaching time and width of the breach. It showed that the breach width is more sensitive to reservoir fill capacity and there is a linear relationship between water volume reduction ratios and the breach width. Finally, tests of the six cases reveal that the proposed model is sensitive to soil conditions.

Measurement of the Lateral Earth Pressure Coefficient of Clayey Soils by Modified Oedometer Test

Kumail R. Alkhafaji; Mohammed Y. Fattah; Makki K. Al-Recaby

Volume 40, Issue 11 , November 2022, , Page 1376-1384

https://doi.org/10.30684/etj.2022.131675.1046

Abstract

The coefficient of lateral earth pressure at rest (K0) explains the connection between the effective vertical and lateral stresses. Geotechnical engineers have studied K0 for many years ... Read More ...

Characteristics of Asphalt Binder and Mixture Modified With Waste Polypropylene

Mohammed Y. Fattah; Wissam, N. Abdulkhabeer; Miami M. Hilal

Volume 39, Issue 8 , August 2021, , Page 1224-1230

https://doi.org/10.30684/etj.v39i8.1716

Abstract

Improving asphalt materials to develop the overall performance of asphalt binders and mixtures has been the focus of several investigations made over the past few decades. The application ... Read More ...

New Trend to Measure the Saturation Point and Suction in Granular Soil

Ahmed S.A Al-Gharbawi; Mohammed y. Fattah; Mahmood R. Mahmood

Volume 38, 11A , November 2020, , Page 1570-1579

https://doi.org/10.30684/etj.v38i11A.746

Abstract

There are many methods to measure the suction and saturation point of any soil and the most used is Tensiometer. The objective of this research is to investigate a new trend to measure ... Read More ...

Author = Mohammed y. Fattah

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

Abstract

Impact of Dam Materials and Hydraulic Properties on Developing the Breaching Dimensions

Abstract

Measurement of the Lateral Earth Pressure Coefficient of Clayey Soils by Modified Oedometer Test

Abstract

Characteristics of Asphalt Binder and Mixture Modified With Waste Polypropylene

Abstract

New Trend to Measure the Saturation Point and Suction in Granular Soil

Abstract