Building Technology

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    ANALYSIS OF PILED RAFT FOUNDATION WITH FINITE ELEMENT & SIMPLIFIED METHOD
    (university of khartoum, 2018) Aya Mohamed ELfatih Ahmed Mohamed Doolaib
    ABSTRACT This research is aimed to study the behavior of piled raft foundation when different parameters have been changed such as piles numbers, piles diameters, piles length, raft thickness and the amount of axial load embedded in stiff clay. These parameters have been examined by the simplified method and finite element method using a computer program PLAXIS 3D Foundation. The discussion has been made on the total and the differential settlements and the relative proportion of the load carried by the piles. The result for settlement was higher when using PLAXIS 3D and the load carried by the piles was also less than what it takes by the simplified method. Increasing the raft thickness when the number of piles is constant reduces the total settlement from 9.6118mm to 9.6018mm by simplified method and from 22.37mm to 21.91mm when using PLAXIS 3D. The differential settlement is also reduced from 1.83mm to 0.96mm by simplified method and from 3.07mm to 2.07mm by PLAXIS 3D. However the amount of loads carried by piles was reduced from 55.23% to 53.46% using PLAXIS 3D and from 91.4% to 91.12% by simplified method . Moreover increasing piles number, the pile diameter and piles length increases the load carried by the piles and reduces the total and differential settlement. Different configuration of piles length within the group also reduces the total and differential settlement and increases the piles capacity. Whereas increasing the applied load increases the settlement and increases the proportion of load carried by piles . مستخلص البحث هذا البحث يهدف الي دراسة سلوك اساس الحصيرة الخازوقية عند اخذ قيم متغيرات مختلفة مثل عدد الخوازيق ,قطر الخازوق ,طول الخازوق ,سمك الحصيرة و القوة المحورية المطبقة علي الاساس المتموضع علي تربة طينية جسئه .تم فحص هذه المتغيرات بطريقتين الطريقة المبسطة الغير خطية و طريقة العناصر المحددة متمثلة في برنامج PLAXIS 3D Foundation . تناول البحث الهبوط الكلي , الهبوط المتفاوت و نسبة الاحمال التي تأخذها الخوازيق .نتائج الهبوط باستخدام برنامج PLAXIS 3D اعلي من الطريقة المبسطة الغير خطية و نسبة الحمل التي تأخذها الخوازيق كانت اقل من الطريقة المبسطة الغير خطية. زيادة سمك الحصيرة عندما يكون عدد,قطر وطول الخوازيق ثوابت يقل الهبوط الكلي باستخدام الطريقة المبسطة الغير خطية من 9.6118مم الي 9.6018مم ومن 22.73مم الي 21.91مم باستخدام PLAXIS 3D. الهبوط المتفاوت يقل من 1.83مم الي 0.96مم بالطريقة المبسطة و من 3.07مم الي 2.07مم بطريقة PLAXIS 3D,كما ان نسبة الاحمال المأخوذة بالخوازيق تقل من 55.23% الي 53.46% بطريقة PLAXIS 3D و باستخدام الطريقة المبسطة يقل من 91.4% الي 91.12 . كما ان زيادة عدد الخوازيق ,قطرها و طولها يزيد من نسبة الاحمال التي تأخذها الخوازيق و يقلل من الهبوط الكلي و الهبوط المتفاوت ,كذلك استخدام خوازيق ذات أطوال مختلفة في مجموعة الخوازيق ايضا يؤدي الي زيادة نسبة الاحمال المأخوذة بالخوازيق و و يقلل من الهبوط الكلي و الهبوط المتفاوت.زيادة الاحمال المطبقة يزيد الهبوط و نسبة الاحمال التي تأخذها الخوازيق.
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    Road Pavement Design using Available Granular Material in Central Sudan
    (University of Khartoum, 2020) Fathi Mahmoud Mohammed
    Abstract Sudan national highway network expanded too much in recent years, however, constructed roads are facing many performance failures resulting mainly from un sufficient survey of traffic and construction material. There is no enough data regarding natural material for road construction therefore this research mission started by surveying for quarries which are the main source of road material, access their material characteristics then conduct suitable design templates that can accommodate their specifications so as to become design modalities for future use. We’d divided the study area into three sectors, in each sector we’d suggested a new link road to be designed as pilot road. We'd conducted design work using input data from this research results, in addition to data from National Highway Authority (NHA) laboratories archives and traffic counts carried out on 2012 and 2016 via two well know pavement design methods; US- AASHTO1986 and UK TRL Laboratory Report(LT1132)– (Powell et al., 1984), The final results were analyzed and at last available quarries with good granular material are determined and the best road design method had been recommended with justifications.
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    Towards Geotechnical Map of Sudan Using Artificial Neural Network
    (University of Khartoum, 2014) Safa Abdelrhman Abdelgalil Mohammed
    ABSTRACT Artificial Neural Networks (ANN) are form of Artificial Intelligence, which are mathematical models, inspired by the human brain to enable processing information for producing meaningful solutions. The objective of this study is to build ANN model that predict soil profile based on coordinates and depth at different locations in Sudan. Accordingly, the ANN are used for classification of soil properties at different depths for 417 sites in Sudan. Those sites are divided to five zones depending on the type of soil: 137 sites at Center of Sudan, 28 sites at North of Sudan, 90 sites at South of Sudan, 137 sites at East of Sudan and 108 sites at West of Sudan. Neural Networks are constructed and developed to predict soil layers and estimate some soil parameters. Five models are suggested for the overall data, while other five models are constructed for each zone. Each models contain ten neural network, eight of them to predict soil layers and two to estimate soil parameters. Soil profiles are presented by the aid of Rockwork computer program. The success percentages for the five models of zones data are 67% for West of Sudan, 77% for East of Sudan, 84% for South of Sudan, 77% for North of Sudan and 70% for Center of Sudan. While the total data gives less percentages of success counted as: 33%, 37%, 48%, 34% and 42% for the five zones respectively. The results showed that Artificial Neural Networks can be used effectively as a decision support and source of information for soils profiles. It is more efficient to be used for limited areas. Rockworks program is an efficient tool in drawing soil profile x-section. For the five zones the outputs of the Rockworks program showed that it can be used to give very good presentation for soil profile sections.
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    Estimation of Unconfined Compressive Strength (UCS) of Nubian Formations from Point Load Index and Other Engineering Properties
    (University of Khartoum, ) Abbakar, Mutasim Adam Sandal ; Abdul Karim M. Zein ; Building Technology
    Unconfined compressive strength (UCS) is a fundamental property of rocks that is required in designing the foundations of structures but its determination is tedious, time consuming and expensive. It has been a common practice to estimate UCS using indirect methods because they are relatively cheaper, faster, and more convenient to perform in the laboratory and at site. There is no reported research in this regard for local rocks in Sudan.This study involved extensive laboratory testing of UCS, point load test (PLT) index Is(50), bulk density and water absorption,also determination of the Rock Quality Designation (RQD) of Sudanese Nubian Formation (NF) sandstone and mudstone samples taken from Khartoum State and other areas. Statistical analysis was performed in order to develop reliablecorrelation relationships between the UCS and other parameter of rock.From the analysis of a large number of tests data a reliable linear equation with a UCS to Is(50) factor of 10.18 and 18.07 was developed for the Sudanese NF sandstone and mudstone respectively, and a conversion factor of 11.8 for the combination of two types. Correlations have also been abtained for rough estimation of UCS from bulk density, water absorption and the RQD. As a recommendation from this study the developed empirical relationships for estimating the UCS from other rock parameters can be further checked for validation and improved by future data from future research studies.This estimation is helpful for the preparation of preliminary foundation designs purposes for any engineering project in Sudan with reasonable accuracy.
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    Bearing Capacity of Circular Footing on Stiff Clay Overlying Sand with Geotextile Inclusion
    (University of Khartoum, ) Bahga Mustafa Mohammed Fadl- Allah ; Ahmed Mohamed Elsharief
    The objective of this study is to investigate the potential benefits of using geotextile reinforcement inclusion to improve the bearing capacity of stiff clay over very loose to medium dense sand. Six model load tests were performed on two layered systems, namely stiff clay over very loose, loose, medium dense sand with and without geotextile inclusion between the two layers. Another test was conducted on stiff clay only. The experimental model test set-up consisted of a circular tank, steel plate, load frame, and loading system. The tank was divided into two parts: the upper part, in which the stiff clay was compacted at optimum moisture content and maximum dry density and a bottom part in which the sand was placed at the target relative densities. From the experimental test results, the load-settlement curves were plotted and the ultimate bearing capacity was obtained using Log – Log (L-L), Tangent (TIM), 0.1B and Hyperbolic (HYP) methods. Theoretical approaches were used to compute the ultimate bearing capacities of the tests without and with reinforcement. The test results have shown an increase in the ultimate bearing capacities with increase in the relative densities of the bottom sand layer. The bearing capacity increased significantly with the inclusion of geotextile layer.According to (L- L), (TIM), (0.1B), (HYP) and (Analytical) methods the bearing capacity ratio (BCR) is (1.50,1.50,1.56, 1.70 and 1.067) for the case of very loose sand as bottom layer, (1.13,1.16,1.17,1.23 and 1.057) for loose sand case and (1.12, 1.14,1.16,1.19 and 1.044) for medium dense sand case, respectively. The maximum benefit for the geotextile inclusion was gained when the sand was very loose. Slight improvement in the (BCR)was observed when loose sand or medium dense sand were used as bottom layer. Load - settlements curve of the pure clay test plots above or is identical to the load - settlement curveof stiff clay overlying medium dense sand with geotextile layer.The analytical methods were generally in good agreement with the experimental model test results obtained by the 0.1B method.