THE STUDY OF INFILTRATION ON UNSATURATED SOIL FOR NON-ADIABATIC NON-ISOTHERMAL CONDITION
Water infiltration from the ground surface is generally considered to be the groundwater recharge, while some which transform into the vapor phase and back to the groundsurface during evaporation. Therefore, there is an uncertainty in the determination of the volume of water infiltration that bec...
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| Format: | Dissertations |
| Language: | Indonesia |
| Online Access: | https://digilib.itb.ac.id/gdl/view/43946 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | Water infiltration from the ground surface is generally considered to be the
groundwater recharge, while some which transform into the vapor phase and back
to the groundsurface during evaporation. Therefore, there is an uncertainty in the
determination of the volume of water infiltration that become the groundwater
recharge. In this case, the mechanism of water vapor movement inside soil-bare is
influenced by energy equilibrium as well as the characteristics of porous media.
Meanwhile, previous infiltration models have not specifically included the principle
of energy equilibrium, thus is needed to improve the formulation of water
infiltration involving thermodynamics principles.
In this study, groundwater flow equations were reformulated through the concept
of positive infiltration, negative infiltration and simultaneous infiltration,
respectively with a downward orientation, upward, and a combination of both
opposite directions. Conceptual and mathematical models were constructed, with
the resulting infiltration formulation involving thermal components in the form of
the Modified Richard Equation (MRE). The verification was done gradually with a
physical model approach in the form of a soil column test apparatus or an
Infiltration Column and numerical simulation of different element methods through
the Crank Nicolson scheme which wass supported by a series of laboratory tests.
Hypotheses in this study have been answered by the identifying point of optimum
water content infiltration as the turning point of an infiltration gradient in the
equation of Richard-Fajar, especially for the case of simultaneous infiltration with
the continuous flux assumption. The location of the point where the optimum water
content is affected by the size of the porous media grains designed to equal the
granules of sand, silt and clay, in accordance with the AASHTO soil classification
system using silica sand. In this case, the rate of positive infiltration is always
greater than the negative infiltration rate, because the evaporation process in the
porous media layer occurs in the position of dry water content and without the
influence of gravity. |
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