Screw piles are widely used in a variety engineering applications supplying stability against compression, overturning moment, uplift tension, and horizontal loads. Screw pile is a famous solution for support light structures, roads and rail signs which have relatively low-capacity foundation. In this study, the behavior of circular (10) mm solid screw pile models embedded in a bed of soft clay soil covering a layer of sandy soil has been studied. The 200 mm thick sand layer was compacted in a steel container with a diameter of 300 mm into four sublayers. The sandy soil layer was compacted at a relative density of 70%. The 300 mm thick soft clay soil bed with Cu (30) kPa was compacted in six sub-layers on the sandy bottom layer. Model tests are carried out with screw piles with a length of 300 mm, 350 mm and 400 mm and a helix diameter of 30 mm. Also, single and double helix and different S/Dh ratio were used for these piles and a comparative study between screw piles and ordinary piles (without helices) is accomplished. This study revealed that introducing screw pile of double helix increases its bearing capacity in soft clay soil by up to a (4-8) % as compared to a single helix screw pile. The results showed that the behavior of screw pile essentially depends on the geometric properties of the pile. According to the achievements, compressive load capacity of screw piles depends on embedded length, spacing ratio (S/Dh) and number of helical plates.

Granular Pile Anchor (GPA) considers one of the solution foundation techniques, designed to mitigate the lifting of the sole resulting from expansive soils. This study work is to investigate the uplift movement response of GPA in expansive soil and evaluation performance in this soil. The effects of several parameters, such as length (L) of GPA and diameter (D), the thickness (H) of expansive clay layer and the existence sandy soil layer are investigated. The results evidenced the effectiveness and ability of GPA to reduce the lifting movement of the expansive soil and presented that the lifting movement can be decreased with rising length to some extent and the GPA diameter. The lifting movement of GPA-Foundation System is controlled by 3 separate variables, these are L/H and L/D ratios and diameter. The lifting movement can be decreased by up to (47%) if GPA

As a matter of fact, the gypseous soil is usually considered as collapsible soil, such type of soil illustrates high resistance to settlement and high bearing capacity when it is dry, but it loses these characteristics when it is inundated and collapses excessively because of the sudden decrease in the volume of the surrounding soil mass. It is founded in the arid and semi-arid regions of the world in Asia, South Asia (Iraq, Syria, Jordan, Yemen, and Iran), North Africa, North America, moreover, it covers more than (31%) of the surface area in Iraq. Gypseous soil is one of the most difficult problems facing the process of building any project because of the difficulty of preventing leakage of water to the soil in practice. Deep foundation (piles) are one of the most common types used in collapsible soils which penetrating problematic soil layers and reaching more hard ones (end bearing piles) or transfers loads depending on skin friction (floating pile). The current work is directed to study the behavior of single and group driven pile of square pattern (4 piles) in case of floating pile (friction pile) with different spacing (2D, 4D, 6D) and length to diameter (L/D) ratio of (20) in this special medium dense soil (gypsum content 30% and 61%) under axial load condition. The investigation was carried out to measure the soil collapse before and after inundation. The results showed that the group efficiency for spacing 2D is less than one while for spacing 4D and 6D are more than that value. In addition, the spacing 4D was more efficient to carry 4 group pile in both dry and soaked cases, in addition, the result showed a high reduction in the bearing capacity at inundation state of group pile of (82% in gypsum content 30%) and ( 87% in gypsum content 61%) with respect to dry state.

Screw piles are considered as one of the solutions in different complications projects. Performance of circular screw piles group subjected to compressive load and embedded in two layers; soft clay and compacted sandy soils is investigated in this study. The thickness of two layers soft clay and sand soil is 250 mm and 350 mm respectively which are prepared after compacted to sub layers in the container. By choosing different slenderness ratios of L/ D 25, 32 and 39, many model tests were achieved on screw piles group. Single and double helix plates were used in screw piles with constant of helix spacing 60mm. A square pattern of screw piles group with different spacing between piles (1.5Dh, 3Dh, 4.5Dh), where Dh is diameter of helix is adopted in this study. The results of this study showed that the ultimate capacity of piles group was increased by increasing the spacing between the piles until reached spacing 3Dh then begin to decrease when piles extended in sandy soil, while in soft clay the ultimate capacity increase with decrease piles spacing in two cases single and double helix. The increasing percentages for pile spacing 3Dh and 4.5Dh are (55.3% and 39.4%) respectively for L/D ratio 32 and (27.2% and 23.8%) respectively for L/D ratio 39. Also, it is recommended to use screw piles group in case of deep layer of soft clay laying on sandy layer due to high increase in compressive resistance capacity of group when extended in sandy layer.

Stretchable and flexible graphite films can be effectively applied as functional layers in the progressively increasing field of stretchable and flexible electronics. In this paper, we focus on the feasibility of making stretchable and flexible films based on expanded graphite particles on a polymeric substrate material, polydimethylsiloxane (PDMS). The expanded graphite particles used in this work are prepared by utilizing bath sonication processes at the ultrasonic frequency of either the commercially available graphite flakes or graphite particles obtained through electrolysis under the interstitial substitution of silver and sulfate, respectively. The X-ray diffraction (XRD) patterns confirm that, due to the action of the bath sonication intercalation of graphite taking place, the resistances of the as-fabricated thin films is ultimately lowered. Mechanical characterizations, such as stretchability, flexibility and reliability tests were performed using home-made tools. The films were found to remain stretchable up to 40% tensile strain and 20% bending strain. These films were also found to remain functional when repeatedly flexed up to 1000 times.