Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : Stone columns


Strength Improvement of Soft Soil Treated Using Stone Columns

Mohammed Y. Fattah; Mohammed A. Al-Neami; Ahmed Shamel Al-Suhaily

Engineering and Technology Journal, 2015, Volume 33, Issue 8, Pages 1740-1756

A total number of 12 models tests were carried out on models of soft clays of different values of undrained shear strength varying from 8 to 18 kPa. The tests consist of twelve models of stone columns, single column, two-column group, three-column group, four-column group, five-column group and six-column group, in addition to one model of untreated soil.
The undrained shear strength has been measured using portable vane shear before testing and after failure of model. It was noticed that the undrained shear strength of model stone columns increased by about (5.6 -20) % due to the construction of stone columns. The provision of stone column in soft clay bed caused an increase in the bearing capacity of the foundation bed by (1.76 - 2.91) times for floating stone columns and (2.13 – 3.15) times for end bearing columns.

Laboratory Investigation on Efficiency of Model Stone Column Groups

Kais T. Shlash; Mohammed Y. Fattah; Maki J. Mohammed Al-Waily

Engineering and Technology Journal, 2009, Volume 27, Issue 9, Pages 1673-1690

As in piles, the efficiency of a group (Eg) of stone columns is defined as the ratio
between the capacity of the group to the capacity of each stone column in the group
multiplied by single stone column capacity. In this paper, the group efficiency of 24 model
stone columns installed in soft clay is considered. These groups consist of 2, 3 and 4
columns. The tests were conducted on stone columns with length to diameter ratio (L/D) of 6
and 8. A laboratory setup was manufactured in which two proving rings were used to
measure the total load applied to the soil-stone column system and the individual load carried
directly by the stone column. The foundation steel plates have 220 mm diameter and 5 mm
thickness. These plates contain 1, 2, 3 and 4 holes, respectively. The spacing between all
holes equals twice the stone column diameter (D), center to center.
The stone column capacity is taken as the load corresponding to a settlement equals
to 50% of the diameter of stone column. The results illustrated that the group efficiency
decreases with increasing the number of stone columns, also the stone columns with L/D of
(8) provided higher efficiency than those with L/D of (6).

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

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.