DETERMINACIÓN EXPERIMENTAL DE LA RELACIÓN DE POISSON DINÁMICA EN SUELOS GRANULARES

Abstract

In order to determine the dynamic Poisson´s ratio in the central third of compacted samples of granular soils, tests were conducted in an cyclic traxial camera, instrumented and automated in the Engineering Institute of UNAM, in which it is possible to test samples 10.14 cm in diameter and 26 cm in height, the instrumentation consists of sensors to determine: load, displacements, pressure and acceleration. Tests were performed with two different sands: The first is according to USCS classification, a silty sand, SM, “Los Jales”, from the mine “Las charcas”, from the state of San Luis Potosí, México, the second is a poorly graded sand, SP, “La Parota”, from the state of Guerrero, México. The test specimens were formed for compaction using the method proposed by Flores in 1996, which consists of the formation of the sample in ten layers of equal thickness using a rammer with a diameter equal to the radius of the mold, with weights of 0.5 to 6.0 kg. Tests conducted in this study are cyclic triaxials controlled displacement, which were applied semiamplitudes 0.05 to 1 mm with a frequency of 1 hz and twenty cycles. Two non-contact radial sensors were used, placed in the middle third, TM, of the specimen to measure the radial deformation, and two axial sensors, LVDT, placed, one in the half superior third, TMS, and the other one in the half inferior third, TMI, of the specimen, to determine the variation of the axial strain, in each one of the points. Poisson's ratio, υ, was determined, by dividing the values of the radial unitary strain against the axial, for this, unitary deformations were plotted, the trend line was generated by linear regression and the slope of this line was considered the Poisson´s ratio averaged for each trial. Finally, the influence of the analysis variables was determined: Relative density, water content, and confining stress in the Poisson´s ratio.