Evaluation of the expansive and collapsible potential of soils from the Jandaíra Formation: a case study in an urbanized area in Mossoró – RN

Abstract

The understanding of unsaturated soils is essential in geotechnical engineering, especially in semi-arid regions, where climatic conditions favor the formation of potentially collapsible and expansive soils. This paper investigates the behavior of soils susceptible to expansion and/or collapse in the region of Mossoro – RN, located within the Jandaíra Formation. A geotechnical investigation was carried out through laboratory tests, including physical characterization, expansion, collapse, and shear strength tests of the soils, as well as field tests, specifically Standard Penetration Tests (SPT) and auger borings. The results revealed soils predominantly classified as clayey sand and with high penetration resistance. Some samples exhibited expansive behavior, mainly in those compacted with the fine fraction of the soil, showing high expansion stresses, while others displayed collapse under inundation. The evaluation of the direct shear test indicated a typical behavior of sandy soils with a high fine fraction, showing a well-defined peak strength and high cohesion before shearing, which was significantly reduced after rupture, while the friction angle remained practically unchanged.