ResumoEste trabalho analisa o comportamento colapsível de um solo tropical arenoso inundado com diferentes fluidos de saturação que constituem o esgoto doméstico.Para tal análise, foram levados em consideração parâmetros físicos e químicos e aspectos estruturais do solo no âmbito do fenômeno da colapsibilidade dos solos, assim como as principais características dos fluidos de inundação de água destilada, esgoto doméstico e algumas soluções à base de substâncias que compõem os esgotos e as deformações axiais do solo a um metro de profundidade em ensaios edométricos. As propriedades físicas e químicas dos fluidos de inundação e dos solos, bem como a combinação entre tais propriedades, desempenham relevante papel na compreensão do fenômeno do colapso, mostrando que a sua ocorrência não pode ser atribuída a um ou outro parâmetro do solo ou do fluido isoladamente.Palavras-chave: esgoto doméstico; constituintes do esgoto; colapso de solos; solos tropicais. AbstractThis article evaluates the collapsible behavior of a tropical sandy soil when exposed to different sewage constituent fluids as wetting fluids. The analysis considers the physical, chemical and structural properties of the soil, as well as soil collapsible behavior, the properties of wetting fluids distilled water, domestic sewage, and some solutions composed by substances that constitute sewage, measuring soil deformation in axial compression edometric tests. The physical and chemical properties of fluids and of the soil, as well as their combination, play a relevant role in the comprehension of collapse phenomena, which shows that its occurrence can not be attributed to isolated parameters of soil or fluid.

Dams pose a high potential risk due to the possibility of rupture. An accident can cause severe consequences for the economy and the environment, besides the loss of human lives. In addition to large dams for power generation, there are also a large number of small earth dams throughout the world, mainly in rural areas, built for the purpose of irrigation or watering animals. Problems with small dams are also frequent, especially in periods of high rainfall when they are more prone to failure. When dams are in cascade, the probability of a rupture is even greater than with an isolated dam, since in most cases small dams do not have enough freeboard to contain the volume coming from the dam further upstream. However, Brazilian legislation relating to water dams only covers the large ones, unless they are classified with high Hazard Potential (DPA for its acronym in Portuguese). Thus, there is no specific legislation for small dams, which means that many of them do not undergo regular inspections and proper safety assessment. This work aims to apply the simplified classification developed by the National Laboratory of Civil Engineering (LNEC for its acronym in Portuguese) for dams in cascade and to compare it to the classification of the Brazilian law for the DPA, evaluating its applicability for small dams. In this way, this method will complement and facilitate decision-making by owners and regulators, thus allowing special attention to the safety of small dams all over the world. Keywords: dams in cascade, dams safety, small earth dams.