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Article
DECREASING PERMEABILITY OF GYPSEOUS SOILS BY BENTONITE

Authors: Baydaa Hussien Moula --- Mehsun Abd Farhan
Journal: AL-TAQANI مجلة التقني ISSN: 1818653X Year: 2010 Volume: 23 Issue: 1 Pages: 179-184
Publisher: Foundation of technical education هيئة التعليم التقني

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Abstract

Soils containing gypsum as a cementing agent are affected considerably when subjected to change in water content. Flow through gypseous soil causes serious damage to the foundation built on such soils. This behavior of this soil exhibited significant changes upon addition of water, especially when the process was accompanied by a continuous flow of water. The addition of relatively small amount of bentonite (3-20%) can improve the performance of granular gepseous soils providing allow permeability and an enhanced mechanical stability. A laboratory investigation of leaching-collapse test behavior of compacted mixtures of soil-bentonite had been undertaken. The study showed that the value of permeability and solubility for treated gypseous soil with bentonite improved by (9-30%) than untreated samples for two different densities

تتعرض الترب التي تحوي على الجبس والذي يعمل كمادة رابطة الى مشاكل معينة عندما تتعرض الى تغيير في نسب المحتوى المائي لها. يسبب الجريان خلال الترب الجبسية مشاكل خطيرة على أساسات الأبنية الواقعة عليها. ان هذا التصرف لهذه الترب يبدو واضحا عندما تتعرض الى تغير في محتوى الماء وخصوصا عندما تتعرض الى جريان ماء مستمر. إن إضافة نسب معينة من مادة البنتونايت (3-20)% من وزن التربة يسهم في تحسين اداء هذه الترب وخصوصا فيما يتعلق بالنفاذية ومن ثم استقرارية هذه الترب. لقد تم اجراء فحص (الغسل- الانهيارية) على مجموعة من النماذج التربة والمضاف اليها نسب من البنتونايت, فلقد اظهرت هذه الدراسة تحسن النفاذية والذوبان للنماذج المعالجة بنسبة(9- 30)%من النماذج الغير معالجة بالبنتونايت ولكثافتين مختلفتين


Article
Settlement and Collapse of Gypseous Soils

Authors: Ahmed A. H. Al-Obaidi --- Ibtihal H. S. Al-Mafragei
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2016 Volume: 23 Issue: 1 Pages: 20-31
Publisher: Tikrit University جامعة تكريت

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Abstract

The work in this research presents an experimental, theoretical and field study in order to investigate the settlement of Gypseous soils and the effect of water percolation on collapsibility of this soil. In this research, more than five sites where chosen to extract the gypseous soil samples with different gypsum content; the sites located in different regions in Salah Aldeen Governorate. In order to estimate the settlement and collapse of gypseous soils, field tests consist of standard penetration test for depths (1m to 5m) for each site and plate load test were conducted in dry and soaked cases.The results show that the settlement of gypseous soils in dry condition is less than the same soils that have low values of gypsum in its formation, the settlement value of lightly gypseous soils can be evaluated from the basic equations depending on data of SPT.In soaking case with short term flooding, gypseous soils shows compressible and they are sufficiently reliable soil base, while in the case of long term flooding settlement develops due to dissolution of salts and gypsum. The magnitude and the rate of the settlement depend on initial gypsum content, relative amount of leached salts, the mineralogy and type of soil and soil properties and acting load. The standard penetration test does not use in calculating the settlement for the soils that have gypsum in its formation in soaking condition.

Keywords

Gypseous soils --- Settlement --- Collapsibility --- SPT --- PLT


Article
Physical Properties of Gypseous Soil after Gypsum Removal using EDTA Solution

Author: Farouk Majeed Muhauwiss
Journal: Tikrit Journal of Engineering Sciences مجلة تكريت للعلوم الهندسية ISSN: 1813162X 23127589 Year: 2018 Volume: 25 Issue: 2 Pages: 68-73
Publisher: Tikrit University جامعة تكريت

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Abstract

The main structural problem in construction on gypseous soils is due to the melting of the gypsum when exposed to water. This may be creating voids in the soil leading to rearrangement of the soil structure and moving the soil particles to more stable positions. This can cause excessive settlement which directly affects superstructures. This study, investigates the influence of gypsum removing on granular soil classification. Four gypsum soil specimens were taken from Al-Qadisiyah district in Tikrit at different depths from the natural ground surface. The depths adopted were 0.75, 1.10, 2.00 and 3.30 m. The corresponding gypsum content was 42.23%, 32.50%, 8.75% and 19.82%, respectively. The EDTA solution was used to disassemble and remove the gypsum particles by washing using distilled water. The results showed that EDTA solution and washing with distilled water was an effective method to remove gypsum from granular soils. Gypsum ratio was reduced to less than 2% in all tested specimens. The percentage of organic matter was not affected, and the specific gravity of the specimens increased between 2% and 12%. The gypsum removal process affected the granular distribution curves of the soil specimens and led to a decrease in the rate of soil grain diameters. In general, classification process of the soil before and after the washing of gypsum from the soil was not affected.


Article
PREDICATION COLLAPSE OF GYPSEOUS SOILS DUE TO WETTING
تخمين انهياريه التربة الجبسية بواسطة الغمر

Authors: Baydaa Hussien Moula --- Namir K. Al- Saoudi
Journal: AL-TAQANI مجلة التقني ISSN: 1818653X Year: 2010 Volume: 23 Issue: 4 Pages: 157-164
Publisher: Foundation of technical education هيئة التعليم التقني

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Abstract

The gypseous soils are considered as one type of collapsible soils ; this is because the gypsum present between the soil particles provides an apparent cementation in the form of bonds that tightened the soil particles together. Upon wetting , these bonds are lost gradually leading to the collapse phenomena.The collapsibility of gypseous soils may occur under conditions that of flowing water, the flowing water will tend to wash salts present in the soil particles.The collapsing behavior of this type of soil generally occurs when the water is introduced into the soil . technically , the collapsible soil obtains some of its strength from cemented / bonding between the soil particles . in the arid region / Middle East , the Aeolian sand which was loosely placed, and upon some cementation , process may become a collapsible soil (high strength when it is dry ) . some cracking of building in this region , however, may be attributed to the introduction of water / moisture after the building is occupied .i.e. settlement of the soil after water is introduced via gardening , drainage, cooking water, bath, sewer line, septic bed, ect., from this research we get that the greater the collapse potential , the greater is the collapse and the damage to structures built on such soils. The soils with Cp less than 1 generally cause no problems to foundations . for Cp =1 to 5 , these will be moderate trouble to the foundation. For Cp≥5 , these there would be trouble if precautions are not taken in the design and construction.

تعتبر الترب الجبسية إحدى أنواع الترب الانهيارية وذلك لاحتوائها على نسب عالية من مادة الجبس والذي يعطيها قوة وترابط بين ذراتها فعند الغمر سوف تفقد هذا الترابط تدريجيا مؤديا حدوث ظاهرة الانهيار .انهياريه تلك الترب تحدث نتيجة لجريان الماء فيها عن طريق رش الحدائق , البزل , مياه الطبخ , الحمامات وأنابيب المياه الصحي والذي يسبب غسل الأملاح الموجودة بين ذراتها مسببا التصدعات في الأبنية الموجودة على تلك الترب في تلك الأماكن. على الرغم من أبداء تلك الترب مقاومة عالية عندما تكون جافة كما هو حال الترب الموجودة في المناطق الجافة والشرق الأوسطية, إن النتائج التي تم استحصالها في هذا البحث أن تربة ذات انهياريه عالية أذا كانت قيمة طاقة الانهيار C.P. عالية, حيث تم حصر قيمها بين 1-5 % وتم اعتبار الترب ذات C.P≥5 ترب ذات مشاكل مما يستدعي اتخاذ الاحتياطات اللازمة في التصميم والإنشاء عليها


Article
THE EFFECT OF USING LAYERED GEOGRID REINFORCEMENT ON THE COLLAPSIBILITY OF GYPSEOUS SOILS

Author: *Raghad Mohammed Kudadad
Journal: Journal of Engineering and Sustainable Development مجلة الهندسة والتنمية المستدامة ISSN: 25200917 Year: 2018 Volume: 22 Issue: 4 Pages: 39-56
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

The geotechnical engineering considers the gypseous soils as collapsible soils. The existence of these soils causes problems for the structures, because of the dissolution and filtration of the gypsum from soil texture by the flow of water through the soil mass, this problem was the focus of attention of many researchers over the years to improve the properties of these soils. This research aims to study the effect of using geogrid reinforcement to reduce the collapse of gypseous soils upon soaking. A series of laboratory models tests in addition to routine laboratory tests carried out on three soils with different gypsum contents. The soils were brought from AL-Najaf district, the first soil S1 was taken from 0.5 meter below the ground surface with high gypsum content (26%). The second soil S2 was taken from 4 meter below the ground surface, with Slight gypsum content (6.9%), the third soil S3 was artificially prepared, by mixing the first soil S1 with the second soil S2 to get the required moderate gypsum content. A new technique manufactured locally for this work and a series of tests including dry and soak tests carried out using steel container (280×280×250) mm. The soils were placed in steel container at their field densities. The single layer geogrid reinforcement test was conducted by placing the geogrid layer at three different depths for all soils [(Depth of the reinforcement layer, D = 0.25 width of foundation, B), (D = 0.5B) and (D = 0.75B)]. The study includes also the effect of number of reinforcing layers (N) on the collapse behavior of gypseous soils. The models were reinforced with N=1, N=2 and N=3 (the vertical distance between geogrid layers, Z=0.25B). The study includes the observation of collapsibility of soaked gypseous soils at stress level of 100 kPa. A strip footing of (270×40×30) mm dimensions was taken as a testing model. This footing was placed at the center of the top surface of the bed soil. For all testing models, the footing was loaded gradually up to 100 kPa, after 24 hours, the corresponding settlement was recorded. Then, the soil is soaked for 24 hours and the generated settlement recorded under the same stress level 100 kPa. The results showed that the most effective depth for single layer reinforcement is at (D=0.25B) for the three soils, which gives a collapse reduction factor (CRF) of about (28.5%, 29.41%, 30.43%) for soils (S1, S2, S3) respectively. The effective number of reinforcement layers was (N=3: D=0.25B: Z=0.25B), which gives (CRF) of about (54.08%, 82.35%, 69.56%) for (S1, S2, S3) respectively compared with unreinforced model.

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