The mining industry consists one of the main sectors of Brazilian economy. Among the mineral resources explored in the country, stands the zinc ore. This activity, which involves the extraction and processing of the ore, results in the generation of high amounts of waste. Direct dumping of these materials into reservoirs contained by dikes is historically the most common form of disposal of mining waste. However, these dams consist of large earthworks with high impact and environmental risks. Recent examples of dam ruptures with major environmental damage and loss of life, such as in the city of Mariana (Minas Gerais, Brazil), in 2015, increased the concern of the technical environment. In this context, this research focuses on the study of the geomechanical behavior of zinc tailings through undrained triaxial tests. This type of test aims to simulate the actual field situation in the laboratory, with the saturated samples under different effective stresses. Then, these samples are sheared with controlled measurement of axial loading (σ1), confining tension (σ3), pore pressure (μ), axial deformation (εa) and volumetric deformation (εv) throughout the test. The material used in the current research comes from the zinc mining process, in which the waste is dumped in the mud dam. Thus, this work characterizes and evaluates the stress state of zinc mining tailings from non-drained triaxial tests submitted from low to high effective stresses (from 20 to 4000 kPa). The results reveal that the material has a granulometry distribution of sand with fines and noted that increasing the confining stress, the undrained resistance also increased. The shear strength parameter, effective soil friction angle (ϕ’), was equal to 36,9°, which was compatible with the references.