Investigation into Some of the Engineering Properties of Soils in Debre Markos Town
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Date
2014-06
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Addis Ababa University
Abstract
Investigation of the ground conditions is used for the economical design of the sub structure. It is also
necessary to obtained sufficient information on type, characteristics and distributions of a soil and rock
underlying a site for proposed structures.
Investigating the engineering properties of soil found in Debre Markos town is the objective of this
research. Because now a days Debre Markos is under development but there is no investigation work
for most of the undertaking construction. To achieve the objective nine representative test pits were
excavated to take representative disturbed and undisturbed samples at the average depth of around
1.5m and 3m.
Study of engineering properties such as the grain size distributions, consistency limit, compaction,
UCS and one dimensional consolidation parameters is important to understand the behavior of soils.
The grain size analysis test result showed that the dominant proportion of soil particle in the research
area is clay, which have clay content ranging from 50 % – 73% , silt faction 15.88% – 40.21 % and
sand fraction 0.36% - 13.28%.
The result of Atterberg Limit test on the soil in the research area showed a liquid limit ranging from
45% – 68%, plastic limit ranges from 18% – 38% and plastic index from 15% – 40%.
The Specific Gravity ranges from 2.69 to 2.84. The Free swell test result on the samples collected
shows range from 30 – 50% except TP 9 which was 180% because a sample on TP9 is expansive soil.
From the compaction test results the maximum dry density (MDD) of Debre Markos soil ranges from
13.5kN/m3 to 14.2kN/m3 and the optimum moisture content ranges 28% to 36%.
The values of unconfined compressive strength (UCS) range from 320.21kPa to 382.96kPa at natural
moisture content of 41.2% to 26.7% respectively.
According to the AASHTO Classification System the usual types of significant constituent materials of
the Debre Markos soil is clayey soil. In Unified Soil Classification System, the soil is categorized as
silty clay.
Finally one-dimensional consolidation test was done. It showed that the area under investigation is
over consolidated in its natural state, have compression index ranging from 0.14 to 0.32 recompression
indexes, Cr, from 0.003 to 0.07, coefficient of permeability ranging from 10-7 to 10-9 cm/sec.
Investigation in to some of the Engineering properties of soils in Debre Markos
Town
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Keywords
Soils in Debre Markos