Applicability of Reversed Experiment Technique to Determine Dynamic Characteristics of Saturated Soils
The problem of determining the penetration resistance of the flat end projectile into dry and water-saturated sandy soils with the use of the reversed experiment technique is studied in the paper. In the experiment, the container with soil strikes the end of the measuring rod, and the resistance force is determined based on the strain gauge readings on the surface of the rod at a distance from its end. The propagation of pulse compression resulting from the impact of the rod flat end against the container with the water-saturated and dry sandy soils. The compressibility of the soil is described with Hugoniots, and the shear properties of the soil are described with a rational dependence of yield strength of the pressure. Hugoniots of the soils with different water saturation were obtained with the use of a multi-component model of the medium. The dependences of the resistance force of the cylindrical projectile on the time in dry, wet and water-saturated sandy soils were obtained numerically. In wet soils, the the non-stationary phase of power pulse was shorter than in dry soils. The analysis of errors was carried out in determining the forces acting on the projectile, from the values of the strain pulse on the surface of the rod. The effect of geometric dispersion during propagation along the rod pulse compression with a wavelength comparable to the radius of the cylinder was numerically shown. In order to restore the pulse at the end of the rod according to its values on the surface at a distance from the load point, the modified techniques were used after adjusting for variance and with an additional view of the uneven deformation distribution over the cross section of the rod. The distortions of the restored pulse were pointed out, the dependence of errors in determining the maximum value of the duration on the non-stationary part of the initial pulse was received. The accuracy of determining the quasi-stationary value of the resistance implementation after the introduction of amendments related to the dispersion both in dry and in water-saturated soils.