عنوان مقاله [English]
The skirted foundations can be considered to be as new foundation options of shallow foundations including oil and gas storage tanks, wind turbines, oil drilling platforms, and also pier and deep foundations. Skirted foundations are steel or concrete foundations, which have a top raft and a relatively thin plate beneath the periphery, the so-called skirt. The skirts penetrate into the soil beneath foundation and form an enclosure in which soil is extremely confined. The skirts and confined soil behave as a unit to shift loads to the soil at the level of skirt tip. The benefit of skirted foundations over conventional foundations lies in their ease and short time of installations. To study the skirted foundations behavior and comparison with common shallow foundations in terms of the bearing capacity and settlement, laboratory tests were carried out on circular skirted foundation resting on sand layer using physical modeling. In this study, parameters such as ratio of skirt depth to foundation diameter, foundation size, the relative density of sand, and roughness of skirt surface were investigated. The test results showed the overall improvement of skirted foundations performance compared to surface foundations. The enhancement in the bearing capacity as well as reduction in the settlement of shallow foundation increases with increasing skirt depth and decreasing relative density of sand. Bearing capacity ratio of skirted foundations to surface foundations increased about 2.3 to 5 times. In addition, the settlement value of skirted foundation decreased up to 8\% of that a surface foundation. In this paper, based on the obtained results, charts are presented to estimate bearing capacity enhancement and settlement reduction in terms of sand relative density, skirt depth to foundation diameter ratio and roughness. Skirted foundations resting on loose sand are more beneficial than those resting on medium and dense sand.