Subsurface Explorations and Investigation of Foundation Performance for Distress Assessment of a Building

The serviceability limit of the foundation system plays an important role in the safe long-term performance of a building. Under governing load cases in service life, the building foundation system should satisfy the serviceability limit state, i.e., total and differential settlement criteria. This study investigated the distress of a building through foundation performance assessment incorporating the soil-foundation-structure interaction (SFSI) effects. A spatially variable soil model [zonewise, obtained from field observation and electrical resistivity tomography (ERT) study] was used to obtain the settlement of the foundation system. Engineering properties of the subsurface were estimated from the collected soil samples and field tests. ERT result shows the variability of the subsurface layer. A three-dimensional finite-element model of soil, foundations, and structures was developed to estimate the settlement demand of the foundation and structures. The numerical model includes the geometric variability of all the foundations of the building and subsurface variability. Settlement and bearing capacity demand of the foundations were estimated and compared with the standard provisions. Results obtained show that the building foundation system satisfies the serviceability limit of the foundation system under total settlement criteria. However, the differential settlement of the system exceeds the required limit despite considering the SFSI effects, and is one of the major causes of distress to the building. The main contributions of this study also include establishing the spatial variability of the soil layer through ERT and correlating it with the crack zone in the building.