Numerical Analysis of Circular Skirted Footing in Granular Soil
摘要
In recent years, skirted footings have become alternatives to deep foundations for weak granular soils such as sand near offshore structures, desert regions, river margins, and seashores, etc. Sand, which is abundantly available across India because of its vast coastline and large network of rivers and is a building material, is rather inferior soil if the foundation is directly resting on the sand because, due to small lateral movement, there is a substantial loss of bearing capacity. Poorly graded sand also poses the same undesirable properties, i.e., low stability and large settlement when subjected to load. But if the sand is confined, it forms a mass that has very high stability and good bearing capacity. The confinement of sand with circular skirts increases the bearing capacity and decreases the settlement of footings resting on unstable soils. The focus of the present investigation is the FEM analysis of circular skirted footings embedded in weak soil using PLAXIS-3D. Pressure-settlement behaviour has been investigated for various diameter and skirt depth combinations and compared to the footing without a skirt to determine the optimal circular skirt dimensions. The skirt depth (h) and skirt diameter (d) were regulated from 0.5 D to 3.0 D (where D is Diameter of the footing) and 0.5 D to 1.5 D, respectively. The results of the numerical analysis demonstrated that the addition of skirts to shallow foundations increased the bearing capacity of the foundation system in comparison to those without skirts. The relative change in bearing capacity was observed by using the Bearing Capacity Ratio (BCR) of the circular foundation, which varied significantly between 1.06 and 6.44 for the cases under consideration.