Engineering and Technology Journal

In this paper, soil-water coupling analyses with finite element method are conducted to investigate the long-term displacements of two-pile foundation installed in saturated cohesive soils under different loading condition. As constitutive model for clayey soil, elasto-plastic bounding surface model is considered, which is a sophisticated elasto-plastic model for normally and over consolidated soils. The influence of loading intensity and consolidation process are considered carefully. The analyses showed that the elasto-plastic bounding surface model may provide a realistic stress distribution within the soil mass around the piles. Also as conclusion of a series of analyses, the followings are clarified; 1) the long-term behavior of two-pile group system; 2) the mechanism of how the space between piles affects the long-term displacements.

This paper deals with the results of an experimental study carried out on compacted clayey soil, to investigate the strength and consolidation characteristics of this soil. This soil having special case of standard compaction curve contain two values of maximum dry unit weight and two values of optimum moisture content between these point minimum dry unit weight was occurred.
The results show that the maximum compressive and tensile strength lies on point near the point of second peak on standard compaction curve. Also the maximum bearing capacity and minimum settlement at the same point on standards compaction curve. Finally the preferred zone to conducted the compaction in field at this point where the dry unit weight at this point was 16.5kN/m3 while the moisture content was 18%.

The most common three-phase problem in porous media is the flow of air and water. This is for example found in the unsaturated zone, where water infiltrates through partly saturated pores to the groundwater. Liquid flow in the unsaturated zone is controlled by a combination of gravitational, capillary, and viscous forces. The mechanical behaviour of partially saturated soils can be very different from that of fully saturated soils. It has long been established that for such soils, changes in suction do not have the same effect as changes in the applied stresses, and consequently the effective stress principle is not applicable. Conventional constitutive models, which are based on this principle, are therefore of limited use when analyzing
geotechnical problems that involve the presence of partially saturated soil zones. In this paper, Al-Mdaina trial embankment was the problem analysed. The finite element programs SIGMA/W and SEEP/W were used, and eight noded isoparametric quadrilateral elements were used for modelling both the soil skeleton and pore water pressure. Parametric study was carried out and different parameters were changed to find their effects on the behaviour of partially saturated soil. The
parameters include the modulus of elasticity and permeability of the soil. It was concluded that the effect of modulus of elasticity on the behaviour of unsaturated soil is apparent at early stages of consolidation and diminishes when the time proceeds. When the clay layer consists of soft clay (Esoil <10000 kN/m2), the effect of unsaturated soil is apparent, while the effect of the modulus of elasticity diminishes when the soil is stiff.

Abstract
This paper deals with the effect of stabilizing gypseous soil using two liquid Asphalt
types (cutback and emulsion) on its behavior in shear strength and rebound
consolidation.
Soil-Asphalt specimens had been constructed using various percentages of both liquid
Asphalt types. One group of such specimens were tested in the direct shear box
apparatus to determine the effect of liquid Asphalt on shear strength, cohesion and
angle of internal friction using the unconsolidated un drained test.
Another group of the specimens were subjected to one dimensional confined
compression test using both dry and saturated testing conditions in the consolidation
apparatus.
The effect of liquid Asphalt on the behavior of mixes in consolidation and rebound
consolidation was studied.
It was concluded that gypseous soil is usually stiff in the dry condition, but it is weak
and had a collapsible behavior when saturated. The addition of liquid Asphalt provides
cohesion strength to the soil mass and also acts as a waterproof agent. It creates a type
of elastic properties and reduces the total strain.