Assessment of two nearby interfering strip footings of different embedment depths in saturated cohesive soils

There are instances where foundations are closely spaced, such as around railroad sleepers and foundations close to property lines. In such circumstances, the stress isobars of the separate footings may interact and combine to generate an overlapping stress isobar that affects a wider zone of the foundation soil and alters the individual foundations behavior, which would be different from that of the isolated footings. As a result, an examination of such issues should be conducted by taking into account all the variables that realistically affect the interference behavior of such closely spaced footings. A numerical study is carried out using the finite element program (Midas GTS-NX), and the behavior of closely placed strip footings of different depths embedded in the saturated cohesive soils is investigated under the influence of different factors such as the spacing between footings, the depth of footings, soil undrained shear strength, and the groundwater table. The evaluated ultimate bearing capacity (UBC) and settlements are represented in terms of non-dimensional efficiency factors for UBC: ξ_L/ξ_R (Left/Right). It was concluded that when the spacing between footings is increased from S/B = 1 to 2, there would be an increase in the UBC of both footings when D_fr/D_fl increases, then the bearing capacity decreases when S/B is increased to 4. For footings of different embedment depths, when the ground water table is deep (at 4 m depth), the values of UBC ratio ξ_R increase with S/B while ξ_L decreases. This is because of various embedment between the two adjacent footings. In all cases, when the ground water table is at the ground surface, lower values in ξ_L are at Cu = 60 kPa, while the higher values in ξ_R are found at this strength.