الفهرس 
Concept of Unsaturated SoilsOnly 14 pages are availabe for public view
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Abstract
Study of unsaturated soils is extremely important because these soils are
broadly encountered in geotechnical applications like: Roads, Embankments,
Airports landings …etc. Compacted soils are considered to form a wide branch
of unsaturated soils. During compaction process, water is added to soil to reduce
its volume by removal of air from voids. But, the entire amount of air can’t be
totally removed. Hence, the soil remains unsaturated. Compacted soils are
subjected to different degrees of unsaturation during their service life because of
rise or DROP in ground water table and rainfall. Thus, it is important to study
compacted soils under framework of unsaturated soil mechanics.
Soil-Water Characteristic Curve “SWCC” (matric suction to water content
relationship) is one of the essential characteristics of unsaturated soils. It
describes the soil water retention properties and how it desaturates under suction
increments. Shape of SWCC depends on pores geometry and connectivity in a
soil. SWCC is influenced by many factors such as mineralogy, stress history,
texture, compaction conditions…etc.
The main target of this research is to investigate the influence of compaction
conditions on the behavior of soil-water characteristics of two types of
unsaturated soils. Initial compaction water content and compaction energy were
chosen as main parameters to create different SWCCs.
Thirty six Samples were compacted according to Standard and Modified
Proctor Energy compactive efforts. Initial water contents were chosen as dry
(less than optimum), optimum, and wet (more than optimum) for each
compaction effort. Two soils were chosen, well-graded sand (SW) and highly
plastic Clay (CH). The considered samples were cores of 4.6 cm diameter and
2.5 cm height prepared for measurements of SWCCs using Pressure Plate
Extractor (suction range was 0.001 – 15 bars). Three samples were extruded from
mould in each compaction condition. Twelve compaction conditions were
considered.
Results showed that the variation of initial compaction water content has an
insignificant influence on SWCCs of sandy samples compacted to Standard
Proctor energy. Different initial water contents influence became more dominant
when compaction effort was increased from Standard to Modified Proctor
energy. While for clayey samples, initial compaction water content has a
significant influence on SWCCs of samples compacted to Standard and Modified
Proctor energies.