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This research is based on the results of 120 determinations of the shear modulus (G) of a saturated granular medium (20-40 Ottawa sand) for different conditions of relative density (Dr), effective consolidation pressure (σ’c), and level of torsional excitation (Te) obtained through the measurement of the resonant frequency (Fr) in resonant column equipment. The tests were performed with relative density values equal to 20, 40, 60, and 80 %; effective consolidation pressures of 50, 100, 150, 200, 250, and 300 kPa; and torsional excitations of 0.025, 0.05, 0.1, 0.2, and 0.4 V. The proposed experimental program is described in detail, in addition to the systematic process of analysis to properly study and interpret the results obtained for samples subjected to cyclic loading. In general, the results indicate that it is possible to establish very simple empirical functions of the resonant frequency as a function of the angular strain and of the effective consolidation pressure. It is concluded that is statistically significant to consider the shear modulus and the resonant frequency related by a constant value M for each type of soil. In this sense, a methodology is proposed herein to be able to obtain from a very small number of tests the variation trends of the shear modulus as a function of the angular strain for different effective consolidation pressures.

The execution of permeability tests using a triaxial cell makes it possible to eliminate the uncertainties that characterize tests performed using conventional equipment. This paper contains the results of 48 tests carried out on three materials recovered from tailings of Riotinto mines (Spain). The equipment involved a modified triaxial system to facilitate the execution of permeability tests under constant head. The tests were performed on samples consolidated to 50, 100, 200, and 300 kPa for four different hydraulic gradients established by applying a backpressure difference (ΔBp). The magnitude of the backpressure difference was applied as a percentage of the initial effective consolidation pressure, expressed as ΔBp/[Formula: see text]; namely, values of 10%, 15%, 20%, and 25%, which resulted in hydraulic gradients between 5 and 80. The backpressure (Bp) was constant (400 kPa) in all cases, allowing a degree of saturation close to 100% to be achieved. This was verified by calculating Skempton’s B parameter, which was very close to unity in all cases. The results indicate that it is feasible to define an empirical function including the coefficient of permeability (k) and the effective consolidation pressure ([Formula: see text]), the mean effective confining pressure ([Formula: see text]), and the backpressure differential (ΔBp).

Extracted samples of L3 vertebrae, the healthy, osteopenic and osteoporotic from Mexican men, were fixed to carry out measurements of the modulus of elasticity (ME) and the minerals content, on the trabecular zone to study their behavior as a function of age.To determine the ME the immersion ultrasonic method (IUM) was used, X-ray dispersion was applied to know the chemical element concentration (Ca++, Na++, P, and Mg++) and computerized axial tomography (CAT) to obtain bone mineral density (BMD).The samples were organized in four groups by decade. The samples in the range of 30-39 years revealed: a normal BMD and a concentration [% w/w] between pairs of Ca++/P, Ca++/Mg++, P/Mg++ and Mg++/ Na ++ with correlation positive due to the strong dependence between them.The average ME results were: 2.79±0.326, 2.68±0.45, 2.66±0.43 and 2.70±0.397 [GPa] for each decade respectively. The ME profiles show a nonlinear behavior as a function of age, indicating a minimum value in the third decade, similar behavior is observed in the Ca++. An exponential behavior between ME and T-score was obtained. The plotted Ca++ and ME as a function of area showed a homogeneous distribution for the first and a non homogeneous for the second.