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This paper explores the possibility of using cement and micro silica as additive materials to mitigate the collapse potential of gypseous sandy soil for both short and long term conditions. Several series of tests were conducted on natural and improved gypseous soil. These tests involved single collapse test and standard Proctor test. The samples were prepared from natural gypseous soil with different percentages (2, 4, 6, 8 and 10%) of cement by weight. Then, the optimum percentage of cement is mixed with the various percentages of micro silica. The results of single collapse tests on gypseous soil indicate that the reduction rate in collapse potential of samples is (65.4%) when treated with 6% cement and cured for 30 minutes. While the gypseous soil improved with cement-micro silica (specifically, 3% cement: 3% micro silica), the reduction rates were (68.9%), (74.8%), and (86.9%) for samples cured for 30 minutes, 28 days, and 56 days respectively. Furthermore, gypseous soil improved with 6% cement exhibited a significant reduction in collapsibility, while the gypseous soil improved with cement-micro silica yielded the best results in terms of collapsibility reduction compared with the influence of cement additive alone. [ABSTRACT FROM AUTHOR]

The presence of gypsum within the soil mass leads to considerable construction problems when the soil underneath is exposed to water. This study's main goal is to improve gypseous soil's potential to collapse using carbon fiber additive. Three percentages of carbon fiber (i.e., 1%, 2%, and 4%) were added to the highly gypseous soil brought from Al-Ramadi city in Iraq with gypsum content of 70%. The soil deformation and collapsibility treatment were investigated by using an oedometer device and Soil-Model Apparatus with dimensions (30*30*30 cm3). All test models were prepared with an initial density of 1.3 gm/cm3and moisture content of 2%. The results of the tests showed a significant reduction in the collapse potential of the soil sample upon treatment with fiber carbon additives. It was noted that the result of collapsibility of Soil-Model Apparatus for 0%, 1%, 2% and 4 % percentages of carbon fiber addition is 4.8%, 3%, 4.1%, and 3.1%. The best results are the lowest percentage of collapse potential at 1% additive is 2.9% in Soil-Model Apparatus. Collapse potential of Oedometer device of 0%, 1%, 2%, and 4% percentages of carbon fiber addition is 4.5%, 3.2%, 3.8%, and 2.9%. [ABSTRACT FROM AUTHOR]

The objective of this study was to examine the behaviour of swage piles, which are frequently used in highly difficult-to-drill soils or offshore structures, under various conditions. This type of pile is defined by its reduced cross-section and its structure, which often takes the form of a steel pipe pile with a plug and a shoe with a cone-shaped end. An experimental study to investigate the behaviour of swage piles in dry sand was conducted on a small scale utilising 1 g scale model testing. The experimental models considered included several types of sand with different relative densities (loose, medium, and dense). The load capacity and swage pile behaviour based on different plug tip angles of 60°, 90°, 120°, and 180° were also investigated. The experimental results showed an increase in the tip angle (θ) of the swage pile under dry soil conditions at identical relative densities of soil, which led to an increase in the ultimate load capacity of the swage pile. When the conical tip angle decreased from 180° to 120°, 90°, and 60° in dry sand set-ups with relative densities of 30%, 50%, and 80%, the load capacity decreased by 18%, 38%, and 61%; 27%, 36%, and 50%; and 28%, 49%, and 56%, respectively [ABSTRACT FROM AUTHOR]