A simplified analytical method for soil penetration analysis

Abstract

A new one‐dimensional model for penetration analysis of a rigid projectile into a soil target is presented. The soil medium is represented by a set of discs of constant thickness, responding in the radial direction under plain strain regime. When penetration through a typical disc occurs, the projectile displaces soil material and a radial plastic shock wave propagates in the disc. The interaction pressure between the projectile and soil material is compatible with the motion of the contact boundary, between them. The instantaneous resistive force is obtained by summation of the contributions of all the discs which are in contact with the nose surface of the projectile. Soil is considered as a ‘floating’ ideally locking material, in which the locking volumetric strain is adjusted to the physical stress–strain properties of the soil material. Friction between projectile and soil is assumed to be negligible. Comparison is made with both twodimensional computer program results and experimental data, and very good agreement is observed. Comparison with other analytical methods reveals that the present model most closely resembles existing experimental results and permits further analysis of the problem as predictions of target response and of stress distribution on the projectile nose. The calculations require very small amounts of computer time. Analysis with the present model yields an efficient and comprehensive means to analyse penetration and perform parameter analysis.

Oblique and normal perforation of concrete targets by a rigid projectile

“…More recently, Chen and Li [16] and Li and Chen [17,25] suggest two dimensionless numbers, i.e., impact function I and geometry function N of the projectile based on dimensional analysis and the dynamic cavity expansion theory, which dominate the penetration of a hard projectile into concrete target. The discs model developed by Yankelevsky and Adin [19] and Yankelevsky [11] is just similar to the cylindrical cavity expansion, i.e., the concrete is idealised as a series of thin, independent layers oriented normal to the penetration direction, and expands radically.…”

Penetration of an exisymmetric conical hammer into frozen soil

“…The irreversibility of soil deformations during the introduction of hammers was considered in [2,5], in which a close approximation was adopted...it was assumed that a plastic medium behind the shock wave front is deformed to some density which is a constant value, independent of the amplitude of the shock wave. Such an approximation permits an analytic solution to the problem to be derived, but for comparatively small initial hammer speeds, when the bulk deformation of the soll is highly dependent upon load application, this is a rather rough estimate.…”

“…For small angles at the vertex of a cone (a narrow body of revolution), the surfaces along which the soll particles are moved are similar to planes perpendicular to its axis of symmetry; in this case it is appropriate to utilize the hypothesis of "planar sections" [2,5,6]. The problem is hereby substantially simplified and is reduced to studying the motion of a medium with cylindrical symmetry.…”

Retrieving the constitutive properties of a concrete target from a single instrumented penetration test

“…A number of procedures have been developed for making such predictions and they generally fall into three categories: empirical equations for depth prediction, analytical models, and numerical solutions. The concrete uniaxial compressive strength is commonly used as the key parameter representing the concrete material in the empirical equations and in some of the analytical models (Chen and Li, 2014; Forrestal et al, 1994, 1996, 2003; Forrestal and Tzou, 1997; Frew et al, 2006; Warren et al, 2014), whereas other analytical models (Feldgun et al, 2017; Yankelevsky, 1982, 1983, 1985; Yankelevsky and Adin, 1980; Yankelevsky et al, 2017; Yankelevsky and Gluck, 1980) and most of the numerical solutions represent the concrete material by its constitutive equations, that is, the equation of state (EOS) and the failure envelope. In recent papers (Yankelevsky, 2016, 2017), it was clarified that the unconfined compressive strength does not identify any specific type of concrete and that different concrete compositions may be prepared with similar unconfined compressive strength and yet behave differently under a variety of triaxial tests.…”