The Effect of Interference of Shallow Foundation on Settlement of Clay Soil

Abstract

As a result of urban development, buildings were constructed adjacent to each other due to the limited construction area. As a result of this neighboring of buildings, there are often signs of damage to the structures that indicate a change in the soil’s behavior supporting the structure in terms of bearing capacity and settlement. This paper presents a numerical study using 3D Plaxis application finite element analysis to investigate the effect of the foundation interfering on the settlement of clay soils. This effect is investigated on two types of foundations, a strip foundation of 1 m wide and a square foundation of 1.5 m wide. Three cases of interference and their effect on the settlement are studied, the first case of two adjacent striped foundations, the second case of two adjacent square foundations, and the third case of two adjacent foundations, one of which is striped and the other is square. The study also adopts the imposition of a case study, in which a new building is constructed adjacent to an old building, where the effect of this juxtaposition on the settlement of the foundations of the old building is studied. The investigation results showed that the settlement in the case of adjacent strip foundations increased by 314% over the settlement of the isolated foundation, and the effect ratio decreased non-linearly with the increase in the distance between the two foundations until it fades at a distance of 7B. In the case of adjacent square foundations, the settlement increases by 194% compared to the settlement of the isolated foundation, and the effect ratio decreases non-linearly, with the distance between the two foundations increasing until it fades at a distance of 4B. In the case of a strip foundation adjacent to another square, the settlement of the strip foundation increases by 152% over the settlement of the insulated foundation, while the settlement of the square foundation increases by 164% over the settlement of the insulated basis. The aforementioned results make the option of two adjacent foundations of different types less effective and more acceptable than the two adjacent foundations of the same type. The results of the investigation of a new building adjacent to an old building also show an increase in settlement of up to 177% over the settlement in the isolated building, and also show that when increasing the depth of the foundation of the new building from 1m to 4m that reduces the risks for the old building by 42%.