Fabric-Property Relationships in fine Granular Materials

Abstract

AbstracVIn this investigation fabric-property relationships were studied in a silty fine sand sized crushed basalt-an artificial 'soil' that has previously been used to simulate lunar soil. The fabric was characterized by measuring preferred orientations of grains, and pore size distribution was determined by mercury intrusion porosimetry. When deposited by pouring, the grains acquired strong preferred orientations in the horizontal direction and formed pores between 1 and 30 #m dia. Densification by static or dynamic compaction resulted in near random grain arrangement and pore sizes between 0.1 and 10 ~m dia.Strength in direct shear and one-dimensional compressibility with the associated lateral stresses were measured. The strength was up to 30 per cent higher when the sample was sheared normal to the preferred orientation of grains than when the shearing was parallel to the orientation direction. This is to be expected, as shearing across the preferentially oriented grains should involve breakage or reorientation of many grains. At a given initial void ratio the compressibility of statically compacted specimens was larger (up to 30 per cent higher axial strain) than that of dynamically compacted specimens at very low stresses. At higher stresses both samples exhibited equal compressibility, suggesting that the grains become more randomly arranged at low void ratios (comparing samples of equal initial void ratios).

Study of anisotropic shear strength of granular materials using DEM simulation

“…When natural granular particles are deposited under gravity, their long axes tend to align with the horizontal plane, which is termed the bedding plane. The microstructures of such granular materials show strong fabric anisotropy, as clearly demonstrated by the quantitative measurements of fabric characteristics of naturally deposited and laboratory‐prepared sand samples, undertaken by Oda 1, Mahmood and Mitchell 2, Oda et al 3, Ochiai and Lade 4, Yang et al 5, and others. The shear strength of these granular materials is anisotropic, which means it is dependent on the direction of the applied stress tensor with respect to the bedding plane from a stress perspective, or on the direction of the shear plane with respect to the bedding plane from a kinematics point of view.…”

Minimum cut and shear bands

“…Not surprisingly, the characterisation of fabric has been the focus of numerous investigations into a broad gamut of particulate matter encountered in both industry and nature (e.g. [1,3,4,5]). Our interest here lies in the evolution of granular fabric as it relates to force transmission in the large strain, so-called critical state regime.…”

Ball-Bearing Effect on Shear Behavior of Binary Granular Mixture

“…1. Type A is more elongated and Type B is more round compared with well-known sands such as Toyoura and Monterey sand, whose elongation ratios are 0.7 16) and 0.72 17) , respectively. The particle size ratio  was set as 10 in all cases and the content of small particles W S was varied from 0 to 100 %, as shown in Table 1.…”