It is very important to the design and development of
natural isolating materials Which are used in the cover-up of solid waste landfill, clay soils or mixtures of these soils and some
additions used as an impermeable liner for construction of soli
d
waste landfill, The permeability coefficient of the materials used in the impermeable system is the most important factors to prevent water leakage into the body of landfill site and to prevent the Leachate of leak into groundwater and soil surrounding the landfillsites.
In this research has been the development and design
Oedometer cell to study volumetric distortions occurring in these
soils as a result of exposure of these soils to climatic conditions
during the implementation of impermeable layer or after
implementation due to rising temperatures in landfill because of
biological interactions taking place at these landfill.
It has been modified and the development of Oedometer
cell to become a thermal cell So that it can control the degree of
heat applied to the sample in the ring of device and then measure the volumetric changes in the sample, Oedometer cell has been linked to the permeability test system with variable head to measure the permeability of the testing sample, It was connected with the digital control , measuring and showing system for temperature and load and displacement.
The subgrade soil reaction can be determined by several experimental methods, in site and in laboratory.
In this paper, the value of subgrade soil reaction Ks was measured and calculated by using the oedometer
test. In addition, the variations of K
s in function of void ratio, applied pressure and time were studied.
Three types of normal consolidated clay soil were tested by using odeometer test. The results show that the
variation of subgrade soil reaction in function of void ratio decreases at the beginning of the test until a
determined value, and then this value increases continuously. This phenomenon can be explained by the
fact that while the applied pressure are near the cohesion strength of the soil, the deformation will be
negligible and the value of Ks is very high, then it decreases until a determined value, and after that this
value increases continuously because the sample can not be deformed any more in the oedometer cell.
The value of subgrade soil reaction is variable in function of void ratio, applied pressure, and settlement
and it decreases in function of plasticity.
For an applied pressure, the value of subgrade soil reaction varies in function of time, where it takes a
very high value at the beginning of loading, and then it decreases gradually in function of time until it
stabilizes at the end of the test.
