Main Subjects : Engineering Geology


The Influence of Shell Permeability on Stability of Upstream Slope during Rapid Drawdown – Khassa Chai Earth Dam as a Case Study

Krikar Noori; Sirwan Salim

Iraqi National Journal of Earth Science, 2021, Volume 21, Issue 2, Pages 15-28
DOI: 10.33899/earth.2021.170383

Several factors affect the stability of earth dam during sudden drawdowns such as permeability and mechanical properties of soil, upstream side slope, drawdown ratio, and drawdown rate. This paper investigates the influence of shell permeability on earth dam upstream slope stability and its role in the change of pore water pressure at different locations of the embankment during the sudden drawdown, using different limit equilibrium methods. To accomplish the objective of this study, (Geo Studio 2012 Software) as one of the powerful geotechnical programs was used for the modeling and numerical analysis. The study shows that decreasing in the shell permeability resulted in the reduction of pore water pressure dissipation and variation of shell hydraulic conductivity plays a vital role in the overall stability of the upstream slope under rapid drawdown conditions.

Validity of clay for Al-Fat’ha and Injana formations for the brick and ceramic industry in Nineveh Governorate

Azealdeen Al-Jawadi; Salim Al-Naqeeb; Thanoun Thanoun

Iraqi National Journal of Earth Science, 2021, Volume 21, Issue 1, Pages 42-53
DOI: 10.33899/earth.2021.170381

The scarcity of clay and alluvial deposits in the valley of the Tigris River and its tributaries in the northern region of Iraq called for the search for suitable clays for the construction ceramic industry in geological formations. A geological survey of the mudstone layers of the Al-Fat’ha and Injana formation rocks was conducted in the districts of Al-Hamdaniya, Telkaif, and Al-Shekhan in the Nineveh Governorate. Samples were taken of the layers that have an appropriate thickness and a topographical and mining position that facilitate exploitation in the event of the success of the raw materials for the industry. The study was conducted on five selected clay models from the village of Mehiwarat and the intersection of the Wana-Mosul Dam road, with two models, the village of Al-Nouran and Ain Al-Nouran. The results showed that most of the muddy geological layers are characterized by a high percentage of calcium and magnesium carbonate, and that the lowest percentage of calcium carbonate was in the layers of the Injana Formation taken from the village of Mehiwirat, which amounted to 16.83%, and that its classification is low-liquidity clay. Through the plasticity coefficient diagram and the plasticity limit, it was found that the clays of the Muhiwirat and Al-Nouran areas fell in the preferred range, while the rest were in the acceptable range. The prepared from Mehiwarat clay was characterized by a volume shrinkage of 16.1% and a weight loss of 23.4%, while the results of the tests indicated the brick models prepared from the clays of the intersection of Wana - Mosul Dam Road and Al-Nouran Village were within the category B, all according to the Iraqi standard specifications.

Assessment of Limestone of Ibrahim Formation in Zurbatiya Area, Eastern Iraq for Ordinary Portland Cement Industry

Narjis Al-Ali; Sattar Al-Khafaji

Iraqi National Journal of Earth Science, 2020, Volume 20, Issue 2, Pages 19-32
DOI: 10.33899/earth.2020.170358

Limestone deposits of Ibrahim Formation in Zurbatiya area, eastern Iraq are assessed as raw materials for the industry of Ordinary Portland Cement (OPC). The deposits are widely exposed in the area close to Iraq-Iran borders. Six samples were collected from selected section of Ibrahim Formation, which consists of a succession of well-bedded white to gray limestone interbedded with gray marl and marly limestone. X-ray diffraction results show that calcite is the dominant mineral followed by quartz and traces of dolomite which appear in limited samples. X-ray fluorescence results revealed a noticeable increase of SiO2, which might be due to the effect of limestone by silicification process, so the rocks are considered to be a siliceous limestone. The other oxides (CaO, Al2O3, Fe2O3, MgO, Na2O, K2O, TiO2, SO3, and P2O5) are within the acceptable limits required for cement industry. Cement chemical parameters indicated that there is a decrease in the lime saturation factor (LSF) and an increase in silica ratio (SR) in comparison with the chemical parameters listed by standard specifications due to the increase of silica content. This increase can be adjusted by adding clays, or any other source of low silica content in addition to use iron and alumina as correcting additive materials for the cement mixture.

The effects of weathering on limestone used for building the cemetery wall in Tel Kaif-North Iraq

Azealdeen Al-Jawadi; Thanoon . Al-Dabbagh

Iraqi National Journal of Earth Science, 2020, Volume 20, Issue 1, Pages 65-74
DOI: 10.33899/earth.2020.170331

The purpose of this study is to evaluate the impact of weathering on rocks used in construction during a defined period of these rocks. The field study involves weathering and rock strength measurements using a geological hammer. Laboratory testing for both wall limestone and fresh quarry limestone was performed to determine the bulk density, the porosity and absorption of water, and the durability test was performed for fresh quarry limestone. A polarized microscope and scan electron microscope, petrographic analysis has been conducted for various weathering rates.
Field notes explain the moderate and high degree of weathering and low strength in the bottom of the wall, whilst the top is slightly weathered and high strength. Laboratory notes through stone crushing show a change from white to beige for slightly weathered samples to moderately and highly weathered samples in powder color. Increasing weathering reduces bulk density and insoluble residues, from 13% in non-weathered rocks to 25% in high-weathered rocks the level of insoluble residue increases. Water absorption in non-weathered rocks and high weathering rocks rises from 6% to 14% and porosity from 14% to 27% respectively. Durability tests show that calcarenite exceeds very high durability, high durability calcirudite and calcilutite, and moderately durable calcisiltite. Four types of porosity, intergranular, intragranular, mold and microfracture appear in the petrographic study using a polarized microscope. Clay minerals and iron oxides surrounding the pores appear in weathered specimens, not in fresh, calcite crystal oxidation and secondary calcite growth on the inner surface of voids have also been shown in the scanning of electron microscopes.