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American Journal of  
Geospatial Technology (AJGT)

Investigation into Some of  Engineering Properties of  Soil: A Case in Study in Seka Town, 
Jimma Zone, Ethiopia

Sifilet Nigussie Wakjira1*

Volume 1 Issue 1, Year 2022
ISSN: 2833-8006 (Online) 

DOI: https://doi.org/10.54536/ajgt.v1i1.412
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Article Information ABSTRACT

Received: July 23, 2022

Accepted: August 25, 2022

Published: August 26, 2022

The main aim of  this study is to investigate some of  the engineering properties of  soils 
found in Seka town in order to know the nature of  the soil and also to give information for 
the design, construction and environmental assessment, so that suitable foundation can be 
recommended for better design and construction in the town. Laboratory tests were car-
ried out including specific gravity ranges 2.65 to 2.77, natural moisture content, Atterberg 
limits, UCS  ranges 143.52kN/m2 to 352.92kN/m2, compression index 0.23 and 0.39, and 
swelling index 0.19 and 0.02, MDD ranges from 1.180 g/cm3 to 1.480 g/cm3, and OMC 
range 35.9% to 48.00% and permeability ranges 3.75*10-5 to 2.75*10-4 cm/sec. Based on 
the results of  this study, the grain size distribution indicates all soil samples have more than 
90% fine grained material. Clayey silty type of  soil is dominantly located in the study area.

Keywords
Investigation, Soil Type, Soil 
Strength, Engineering Properties

1 Instructor at Civil Engineering department and Registrar Coordinator of  Engineering and Technology College, College of    
  Engineering and Technology, Dambi Dollo University, Ethiopia.
* Corresponding author’s e-mail: siifnh14@gmail.com

INTRODUCTION
For designing and constructing the foundation for a 
structure, such as a building, plant or bridge; geotechnical 
site investigation is the primary process of  collecting 
information and evaluating the conditions of  the site 
(Ashton & Gidado, 2001), to safe from an adequate 
damage of  the structure. Investigation of  the sub-surface 
conditions at a site is prerequisite to the economical 
design of  the substructure elements, and also necessary to 
obtain sufficient information for feasibility and economic 
studies of  the proposed project (Haruna et al., 2013).
Engineering properties of  soils are investigated by direct 
methods such as borings and trial pits or through indirect 
methods such as seismic acoustic, resistivity and ground 
penetrating radar (Emmanuel, 2014). Site investigation 
is an important part of  civil engineering design whose 
aim is to reduce uncertainty of  ground conditions by 
various combinations of  field and laboratory testing 
(Alemayehu T. and Solomon Y., 1986). However, the 
scope of  site investigations is usually dependent on the 
finances available and time required for carrying out the 
investigation (Jibril, 2017).

METHODOLOGY
Study Area Description 
This study considered Seka town which is found in south 
western Ethiopia, Oromia Region, Jimma Zone, Seka 
Cokorsa Woreda specifically, and it is about 354 Km from 
Addis Ababa. It has latitude and longitude of  7040N 
and 36050 E respectively, and also its average elevation 
1715 m-1835m above sea level. The topography of  this 
region is predominantly flat. This study will be done 
on the expansive soil that had been collected under the 
surface of  the earth in Seka town. It is possible to find 
vehicles for shipment of  the collected samples. The town 
traverses vast flat land that is covered with red clay soil. 

The red clay soil is underlain by natural sand deposit. It 
was estimated that the sand deposit is found at depths 
of  1.0m – 3.0m from the surface of  the natural ground.

  
Experimental Setup
Experimental tests were carried out at the Jimma Institute 
Technology, Jimma University in soil laboratory, Ethiopia.  
A total Sample from 8 (eight) test pit were collected and 
tested. The strength and Class of  the soil of  the town was 
investigated.

Natural Moisture content
The water content is the ratio, expressed as a percentage, 
of  the mass of  “pore” or “free” water in a given mass of  
soil to the mass of  the dry soil solids. The value rang from 
43.54 to 53.51 in percent 

Specific gravity
The specific gravity of  soils found in Seka town falls to 
2.65-2.77 which was in the range proposed by Bowles 
and other researchers. The soil is clay soil and its specific 
gravity varies with the range based on mineral content of  
the soil. 

Grain Size Analysis 
The soils contain 38.44-54.98% clay, 37.56-51.74% silt, 
5.24-9.82% sand and 0% gravel. Summary of  the test 

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Am. J. Geo Spat. Technol. 1(1) 29-33, 2022

result and graph of  combined analysis Atterberg limits

Figure 1: Grain Size Analysis result and graph of  combined analysis is shown respectively 

Atterberg limits
Liquid limit of  Seka town falls in the range of  69.4-90% 
and plastic limit was in the range of  24.67-49.47%. The 

Figure 2: Atterberg limits

AASHTO Soil Classification System
Soil classification of  the study area based on AASHTO, 
all soils fall in A-7-5 and A-7-6. So, the general rating for 
all soil is not fair for subgrade material depend on PI.

Compaction Test
From the test results the maximum dry density (MDD) of  

Seka town ranges from1.359 g/cm3 to 1.480 g/cm3 for 
modified compaction and from1.185 g/cm3 to 1.36 g/
cm3, and the optimum moisture content ranges 29.7% to 
35.50% for modified compaction and 35.9% to 48.00% 
for standard compaction 

Unconfined compression strength (UCS) test
The summary of  the unconfined compressive strength 
and cohesion result of  soils for the area under study 

plasticity index range of  the soils was from 25.93% to 
54.55%. According to Burmister (1947) the plasticity of  
the soils is high plasticity.

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Am. J. Geo Spat. Technol. 1(1) 29-33, 2022

Figure 3: AASHTO Soil Classification System

Figure 4: Compaction Test analysis

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Am. J. Geo Spat. Technol. 1(1) 29-33, 2022

and Fig 8 indicate the graph of  unconfined compressive 
strength of  Seka town area. It is observed that the 
consistency of  Seka soil is low to medium

Pressure – void ratio curve 
The pressure-void ratio curve can be obtained if  the void 
ratio of  the sample at the end of  each increment of  load 

is determined. The basic data used to determine this curve 
are natural moisture content, Specific gravity, density, 
cross sectional area and height of  the sample, initial void 
ratio and applied loads. From these curve important 
parameters such as coefficient of  compressibility (av), 
compression indexes (Cc), Swelling index (Cs) and pre-
consolidation pressure (pc) are determined. 

Figure 5: Unconfined compression strength (UCS) test

Figure 6: Pressure – void ratio curve 

Permeability 
The flow of  water through soils depends upon its 
permeability coefficient I use falling head permeability 
test since this test is appropriate for fine grained soil. Since 
my soil is fine grain soil, I prefer this test. A representative 
permeability tests were run on samples of  two disturbed 
samples on two different test pits, where the remaining 
test pits have the similar result with either of  these test 
pits. In void ratio versus log coefficient of  permeability 
graph all soil samples taken from study area have nearly 
straight-line relationship 
Coefficient of  permeability for TP-2 is 3.05*10^-4, 
for Tp-4 is 3.11*10^-5. The values of  coefficient of  
permeability for the tested soils using falling head test 
lie between 2.75*10-4 and 3.75*10-5 cm/sec, which 
indicates that the soils are practically impervious. Refer 
Appendix-V.

CONCLUSIONS
No significant variations of  engineering properties within 
the investigated depths as well as in different pits which 
were found in the research work. 
According to USCS the soils of  the study area fall 
under CH and MH region, which shows that the soils 

are inorganic high plastic clay and high plastic Silt. And 
AASHTO classified the soil as (A-7-5 and A-7-6).
Grain size analysis result shows the soil under investigation 
is dominantly clay and silt types. Since, 92.2% average of  
the soil is fine grained soil; which have higher in plasticity. 
According to ERA manual not recommended for 
suitability of  soils as sub grade material. Since, Plasticity 
Index is greater than thirty. The values of  specific gravity 
are within the same range’s standards. The moisture 
content of  the soil is medium.
As determined from the one-dimensional consolidation 
test conducted on undisturbed soil samples; we can 
conclude that: Since pit excavation method of  exploration 
is used, the outcomes would be applicable only for light 
structures which under lie their foundation up to depth 
of  3m. Compaction tests results shows that, OMC is 
very high and MDD is very less. Which says that the soil 
is highly compressive. From Unconfined Compressive 
Strength (UCS) result the consistency of  soils is Stiff  to 
very Stiff. And, the values of  Liquidity Index classify the 
soil under the class of  Intermediate strength, which the 
soil deform like a plastic material.

ACKNOWLEDGEMENT
First of  all, I would like to thank the Almighty God for 

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Am. J. Geo Spat. Technol. 1(1) 29-33, 2022

giving me strength and sustain me to complete this works.
My deepest gratitude goes to my advisor, Professor Emer 
T. Quezon his limitless efforts in guiding me through my 
work and for providing me in all directions.
I would like to acknowledge the encouragement given to 
me by my families, especially my brother Tolesa Nigussie, 
for his supporting me in all directions through my work. 

REFERENCES
Alemayehu T. and Solomon Y. (1986). Investigations 

On The Expansive Soils Of  Addis Ababa , Civil 
Engineering Department Addis Ababa University. 
Journal of  EAEA, 7, 1-9

Ashton, P., & Gidado, K. (2001, September 5-7). Risk 
Associated With Inadequate Site Investigation Procedures 
Under Design And Build Procurement Systems. 17th 
Annual ARCOM Conference. University of  

Salford. Association of  Researchers in Construction 
Management.

Emmanuel, S. (2014). Investigation of  Index Properties 
of  a Residual Soil Profile. IOSR Journal of  Mechanical 
and Civil Engineering (IOSR-JMCE), 11(3), 1–4.

Haruna, G., Abdulfatah, A. Y., & Suleiman, A. (2013). 
Geotechnical Investigation into the Causes of  Cracks 
in Building : A Case Study Geotechnical Investigation 
into the Causes of  Cracks in Building : A Case Study. 
Electronic Journal of  Geotechnical Engineering, 18, 2823–
2833.

Jibril, J. (2017). In-depth Investigation into Engineering 
Characteristics of  Jimma Soils In-depth Investigation into 
Engineering Characteristics of  Jimma Soils By. Retrieved 
October 2014, from http://etd.aau.edu.et/
handle/123456789/3626

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