The study presents a comprehensive study on the assessment of the bearing capacity of closely spaced strip footings on c-& oslash; soil, considering spatial variability in soil properties. A linear elastic model is employed for footings and elastic-perfect plastic soil behaviour via the Mohr-Coulomb yield criterion. Soil properties obtained from extensive field investigations of Taranto Blue Clay (TBC) in Italy are modelled as stationary random fields (RFs) generated using the Fourier series method. The cohesion and friction angle RFs are integrated with the Z-soil FE code. The final results are obtained according to the random finite element method (RFEM). The study investigates the influence of spacing distances between footings and spatial correlation lengths of soil parameters on the bearing capacity. Results show how spacing distance affects bearing capacity. Moreover, it indicates that neighbouring footing bearing capacity is strongly correlated with investigated parameters. In the case of small spatial correlation lengths, the patterns were obtained as non-symmetrical, transitioning to more symmetrical patterns at larger lengths. The manuscript concludes by presenting reliability-based design considerations for the ultimate bearing capacity, considering the horizontal spatial scale of fluctuation (SOF). The findings emphasize the importance of evaluating allowable design bearing capacity for proximity structures using RFEM and provide valuable insights into the interplay between spacing distances and spatial variability in soil properties. To this end, the study underscores the critical interplay between spacing distance, spatial correlation lengths, and random soil properties in assessing neighbouring footing-bearing capacities.

This study aims to develop hazard curves to assess the reliability of shallow foundation design on sandy soils. The random finite element method was employed to analyze the elastoplastic behavior of soils with spatially varying deformation modulus and angle of shearing resistance, which were generated as random fields and assigned to the analysis models. The output distributions were fitted with a corresponding probability density function (PDF), and the probability of exceedance (Pf) for determined damage limits was estimated from these PDFs, forming the proposed hazard curves for the determined anisotropy ratios. The method proposed in the study was validated by a database containing field test measurements, and a sample problem was presented to exemplify the application of hazard curves. The significant contribution of this study is to form the hazard curves for superficial foundations on sandy soils by considering both the elastoplastic behavior of soil and the influence of all effecting parameters, which satisfy the serviceability limits in the foundation design codes. The curves proposed in this study provide an approach for probabilistic investigation of superficial foundations taking the variability of sands into account and robust technique for the reliability-based design of strip footings with a serviceability limit state.