Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Improvement


Sand Column Stabilized by Silica Fume Embedded in Soft Soil

Hussein H. Karim; Zeena W. Samueel; Mohammed S. Mohammed

Engineering and Technology Journal, 2016, Volume 34, Issue 6, Pages 1047-1057

This research aims to study the behavior of the sand columns stabilized with silica fume (as an additive with different percentages) and driven in soft soil bed with undrained shear strength (cu) between 16 – 21 kPa. Holesin the shape of columns with diameter 50 mm and length 300 mm have been drilled in a soil bed and backfilled with sand mixed with several proportions of silica fume with 7-days curing. A rigid circular footing with diameter 64.6 mm was located on each column and loaded axially till failure. The results analysis of the model tests indicated an encouraging improvement in load carrying capacity of the columns and considerable reduction in the settlement compared to the conventional stone columns. The bearing improvement ratio and settlement reduction ratio exhibited by the sand columns are 1.18 and 0.71, respectively. The best possible addition of silica fume content in sand–silica fume columns is 7% giving bearing improvement ratio and settlement reduction ratio of 1.56 and 0.5 respectively.

Behavior of Expansive Soil Treated with Silica Fume Material

Zeena Waleed .S. Abbawi

Engineering and Technology Journal, 2015, Volume 33, Issue 5, Pages 1226-1246

This research deals with the improvement of the mechanical properties of expansive clay soils by silicafume. The expansive soil was prepared in laboratory by mixing natural soil brought from (Nahrawan) citywith different percentages of Bentonite (30, 50 and 70%by weight). The test program included the effect of Bentonite on natural soil then study the effect of silicafume on prepared soil by adding different percentages of silicafume(3,5, and 7% by weight) to the prepared soils and the influence of these admixtures were observed by comparing their results with those of untreated soils (prepared soils). The properties chosen for this comparison were specific gravity, the consistency limits, swelling percent and swell pressure. The resultsshow that the plasticity index, the optimum moisture content, swelling percent and swell pressure increase with increasing the Bentonite percent, and the maximum dry density, specific gravity decrease with increasing the Bentonite percent. When the prepared soil treated with silicafume, the results show that plasticity index, specific gravity, maximum dry density swelling percent and swell pressure decrease with increasing the silicafume percent, while optimum moisture content and unconfined compressive strength increased with increasing silica fume percentages. And the perfect percentage of silica fume was obtained to be 7% which where decreased the swell and swell pressure in large percent.
The result showed that the addition of silicafume to expansive soils has in a positive effect to the geotechnical properties and these results will benefit the engineers or decision makers in using this additive.

Improvement of Sabkha Soil by Using Geomesh and Addition of Polycoa

Hassan Obaid Abbas

Engineering and Technology Journal, 2012, Volume 30, Issue 4, Pages 568-576

Sabkha soil is a rich soil with salt deposited which result from evaporation of
water, it is one of the many types of collapsible soils and in turn is one of the many
types of problematic soils. This soil totally has good engineering properties when dry
,i.e ,moderately bearing capacity with low settlement. But once is wetted it loses its
entire structure (collapse) and undergoes very large instantaneous settlement. A
laboratory model test consists of a cylindrical steel container of 270mm diameter and
300mm height, the soil is brought from Al-Khalis discrete. The density of soil is
controlled by placing the required weight inside the container of known volume, to
the required height. A square footing 40mmx40mm makes from steel is used. The
stress is applied from a fixed loading system designed especially for model tests.
In this study two types of improvement are used , the first improvement consists
of fine geomesh under footing at different depth (0.5B,B,2B),the second
improvement is the addition of polycoat with different concentration to surface of soil
.The first method do not give good results of improvement but the second method
gives good improvement which reduces the collapsibility to 62% at stress level of
50kPa.

Behaviour of Encased Floating Stone Columns

Qutaiba G. Majeed; Mohammed Y. Fattah

Engineering and Technology Journal, 2009, Volume 27, Issue 7, Pages 1404-1421

In this paper, the finite element method is utilized as a tool for carrying out different
analyses of stone column–soil systems under different conditions. A trial is made to
improve the behaviour of stone column by encasing the stone column by geogrid as
reinforcement material .
The program CRISP2D is used in the analysis of problems. The program adopts the
finite element method and allows prediction to be made of soil deformations considering
Mohr–Coulomb failure criterion for elastic-plastic soil behaviour.
A parametric study is carried out to investigate the behaviour of ordinary and
encased floating stone columns in different conditions. Different parameters were studied to
show their effect on the bearing improvement and settlement reduction of the stone column.
These include the length to diameter ratio (L/d), shear strength of the surrounding soil and,
the area replacement ratio (as) and others.
It was found that the important increase in strength of stone column occurs when it
is encased by geogrid for (length/diameter) L/d = 8 while in case of L/d = 4, a slight
increase in the bearing improvement ratio at the early stages of applying the load is
obtained and then the value of (q/Cu) for both ordinary and encased stone columns is the
same.

Numerical Study of Forced Convection in Wavy and Diverged-Converged Ducts

Anmar M. Basheer; Sattar J. Habeeb; Waheed S. Mohamad; Qutaiba G. Majeed; Mohammed Y. Fattah; Jawad K.Oleiwi; Mohammed S. Hamza; Mayyadah Sh. Abed; Amjed J. Hamidi; Ahmed Alaa Ogla; Yaser Nabeel Ibrahem

Engineering and Technology Journal, 2009, Volume 27, Issue 7, Pages 1385-1403

A three-dimensional study of developing fluid flow and heat transfer through
wavy and diverged-converged ducts were studied numerically for a Prandlt number 0.7
and 5.85 and compared with flow through corresponding straight duct. The Navier-
Stokes and energy equations are solved by using control finite volume method.
Development of the Nusselt number in wavy and diverged-converged ducts are
presented for different flow rates (50

Keywords

forced convection
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numerical study
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wavy duct
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diverged-converged duct