In soil mechanics there are many unknowns about the behavior of materials and even more great uncertainty generated sands, due to its gradation and shape of the grains is sometimes difficult to know their behavior and especially when trying to study by tests in laboratory. This research contains the results of analyzing the behavior of Guamo sand, representative of research in Colombia material by analyzing the effect of liquefaction flow by performing triaxial undrained (CU), for which he developed a series of tests taking into account the relative density of the material as well as the constructive effect of maintaining a constant gradation samples.