الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Swelling soils include clays and fine silts which swell while getting wet and shrink if they are dry out. Egypt is regarded one of the countries which has new huge developments under constructions on many urban regions containing swelling soils. The structures constructed on these swelling soils may be exposed to high damage if any significant change in the moisture content of these swelling soils occurs, so the presence of such swelling soils represents a significant hazard. This thesis presents intensive review on swelling soil including its origin, major clay minerals classifications as well as the swelling mechanism. Furthermore, the main characteristics and mechanical behavior of unsaturated soil have been discussed for well-understanding swelling soil behavior. Also, all identification methods for swelling soil are reviewed as well as defining all relevant swell characteristics with explaining for the different Oedometer test methods which commonly used in their determination.
Prediction of ground heave resulted from swelling soils can be done using several methods that may be classified into four categories; empirical methods, suction methods, Oedometer test methods, and numerical methods. Numerical methods are regarded the best techniques to predict the ground heave of swelling soils as they can overcome the difficulties of solving the nonlinear differential equations of water flow and soil deformations. Finite element method can be considered as the most promising method. However, an appropriate constitutive model representing behavior of the swelling soil is the main challenge for a representative numerical model to simulate the complex performance of swelling soils considering the soil-water and the soil-structure-interaction. Recently, a new constitutive model specialist in simulating swelling soils and rocks has been implemented as user-defined model for “PLAXIS” program. The concept of this “Swelling Model” as well as its mathematical formulation are introduced and discussed in this thesis.
The numerical analyses conducted in this thesis start with numerical verification to the new introduced “Swelling Model” using available results of Huder-Amberg Oedometer test conducted by (Wittke-Gattermann, 1998) on a rock sample from Germany. The suitability of the model to simulate the behavior of this swelling rock is verified by making a numerical simulation to the conducted Huder-Amberg Oedometer test using “PLAXIS-VIP, 2018” software via Oedometer “Soil Test Facility”. Furthermore, individual input soil parameters are evaluated and assessed through different sensitivity analyses including parameters variations.
Intensive experimental testing program has been conducted on some swelling soil samples collected from some of arid/semi-arid regions in Egypt to determine their swelling parameters. Through this experimental testing program, Oedometer swell test has been firstly conducted on the same soil with two different techniques; namely Different pressure method and Huder-Amberg method. After that, all subsequent experimental tests were performed using Huder-Amberg method as it demonstrated high superiority in determining swelling parameters. Grob’s swelling law was applied to all obtained experimental results to give exact and complete determination for all swelling parameters. Furthermore, the suitability of the “Swelling Model” to simulate the performance of swelling soil is verified by conducting a numerical simulation to one of the Huder-Amberg Oedometer tests. This confirms that the new “Swelling Model” is applicable with both of swelling clay and anhydritic rock and it can simulate them with true results. Furthermore, the obtained swelling parameters for the experimented swelling soil samples are summarized and presented as a useful key-parameters of these swelling soils which can be used as pre-determined inputs in any further numerical analyses.
Finally, the “Swelling Model” is applied with 2D and 3D numerical modelling for three common practical problems including swelling soil. Implementation of “Swelling Model” in both of PLAXIS 2D and 3D is validated from this numerical analysis as well as obtaining the results from them with same high accuracy. The obtained results from the conducted models are presented verifying the ability of “Swelling Model” to deal with different numerical modelling problems. This enhanced numerical analysis will open new horizons in the field of numerical modeling, along with any other similar applications of swelling soils.