No abstract

The pile foundations’ design is commonly based on the soil’s initial in situ condition during field investigations or the assumption of its saturated condition. However, for some regions in tropical weather, a significant part of the pile shaft remains above the groundwater table (i.e., unsaturated condition) during the structure’s lifespan. Only considering a constant moisture condition in the soil (unsaturated or saturated) can overestimate or underestimate the pile design. The soil shear strength governs the shaft resistance of a pile and depends on the soil matric suction, which is significant in the unsaturated zone. In this study, an analytical model is proposed to estimate piles’ unsaturated shaft resistance and encourage the use of unsaturated soil mechanics in engineering practice. The mathematical equation involves well-known parameters from unsaturated soil mechanics theory and simulates the pile shaft resistance variation with its length and time, considering a unidimensional infiltration downwards (e.g., during a rainfall event).

The predicting difficulty of bearing capacity of foundations becomes a major problem due to the constructions with rigorous construction processes. Hence, the soil spatial variability is often ignored in the calculations of bearing capacity of deep foundations. Consequently, the use of statistic associated with bearing capacity calculations has added important failure probability information of piles foundations. Thus, this work presents a methodology for calculating the probability of failure of bearing capacity using the probabilistic method First Order Second Moment (FOSM). The data used come from a residential building in the city of Águas Claras / Federal District - Brazil. Finally, this work provided a methodology for calculating the probability of failure taking into account soil lithology and spatial variability.