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ASSESSING AND COMPARING OF CONSTANT HEAD PERMEABILITY TEST ON DIFFERENT SOIL SAMPLES IN ABAK LOCAL GOVERNMENT
BACKGROUND OF STUDY
The facility at which a fluid is able to travel through soil pores is referred to as permeability. A material is permeable if it contains continuous voids. Binod Tiwari (2008). All materials such as rocks, soils, concrete, etc. are permeable, the flow of water through all of them obeys approximately the same laws.
The permeability of soils has a decisive effect on the stability of a foundation, seepage loss through embankments of reservoirs, drainage of subgrades, excavation of open cuts in water bearing sand, rate of flow of water into wells and many others (Mante, 1960).
The permeability of a soil also has a great influence on plant growth since plants obtain their water and nutrients from the soil, plant growing on highly permeable soil may wilt if they are not watered regularly because water passes so rapidly through the soil that there is not enough stored in the soil pores for plant use. Soils of low permeability generally tend to be water-logged and are consequently poorly aerated, plants growing on such soils have enough water but not enough air, therefore they suffocate and die. Frederick (1963).
Apart from agriculture, knowledge of permeability is useful in the solution of problems involving drainage of airports, highways and playing fields, etc., uplift pressure beneath dams and buildings, landslides, seepage through earth dams, dewatering of excavated sites and many other problems (Mante, 1960).
Methods that are common for determining the coefficient of permeability can be classified under laboratory and field methods, but for the sake of this research, laboratory methods shall be considered. These are:
- Constant Head Permeability and
- Falling Head Permeability methods.
The various types of apparatus which are used in soil laboratories for determining the coefficients of permeability of soils are called permeameter. Apparatus used for the Constant Head Permeability Test is called a Constant Head permeameter and the one used for the Falling Head Test is a Falling Head permeameter (Murthy, 2005). The Constant Head Permeability test is more suited for coarse grained soils such as gravelly sand and coarse medium sand.
Permeability of soil controls the rate at which saturated soils undergo compression below foundations under external loads. Knowledge of permeability of soil is required in determining the discharge or yield designing of the well and hydraulic structures and through earth dams. Permeability is also required in designing filters used to prevent piping failure in earth dams, it also controls the stability of hydraulic structures.
Soils are characterized by swelling, depressions and lateral movement in the presence of water even under moderate wheel loads (Obeahon, 1993). Civil engineering practice and construction works in Nigeria depend greatly upon very large extent of good road networks.
The importance of permeability in many soil problems makes it desirable that it be measured as accurately and as rapidly as possible. Unfortunately, most of the present day methods available for the measurement of permeability take a considerable amount of time and succeed in giving only an estimate of it.
STATEMENT OF THE PROBLEM
The need for this study arises from the fact that poor lateritic soil, in their natural states are at best not suitable for sub-base, because it causes more damage to structures.
The study of the permeability of soils is important in soil mechanics, it is essential for calculating the quantity of underground seepage under various hydraulic condition. In common practice, the permeability coefficient is usually obtained by constant Head Permeability Test and is utilized in filtration, drainage, settlement and stability calculations. For any soil to be suitable for civil engineering projects, they must meet existing requirements (Amadi, 2010) constructions on such areas needs thorough research to find a cost effective way of stabilizing and utilizing them.
SIGNIFICANCEOF THE STUDY
The general objective of the study is to assess and compare Constant Head Permeability test on different soil samples.
The specific objectives of the study are:
- Compare and determine Constant Head Permeability test on different soil samples.
- To determine the relationship between soil permeability on different types of soil.
- To determine the coefficientsof permeability on different soil samples and their effects.
- To perform a permeability test for fine grained and granular soils.
JUSTIFICATION FOR THE RESEARCH
Laterite has different properties – shrinkage and swelling, depending on location, some may not be good materials suitable for direct use in road and building construction in civil/geotechnical engineering project due to different properties they possess (Osinubi, 1995).
SCOPE AND LIMITATION
This research work will be limited to compare the laboratory test used to assess the constant head permeability on different soil materials, regarding the use of lateritic soil if used as fill material embankment.
Compaction test will be carried out using the compaction energies of British Standard Light (BSL). All other tests will be carried out with accordance to BS 1924 (1990) and BS 1377 (1990).
The knowledge gained in the process of this research work will help in solving problems involving yield of water bearing strata, seepage through earthen dams, stability of earthen dams and embankments of canal bank affected by seepage, settlement, etc