Experimental Study on the Characteristics of Granular Materials’ Flows and Fractures under Uniaxial Compression

Futian Zhao,Chen Ou,Yue Wang,Zhimin Xiao,Jun Liu,Mingqing Liu,Mengyang Zhen,Chunshun Zhang

doi:10.1155/2020/8846684

Abstract

The mechanical behaviors of granular materials have high complexity. Since the mechanical behaviors of granular materials are difficult to describe theoretically, in this paper, the flow and fracture characteristics of granular materials were discussed by the experimental method. An experimental method was firstly proposed to identify the mechanical behaviors of granular materials under extra loading. An experimental device, which can be used to monitor force and displacement between particles, was invented. The uniaxial compression experiments of granular particles with different materials and grades were carried out, and the overall and local force between particles was obtained and investigated. Due to the flow of particles, the overall force rises in a fluctuating manner and the local force is not distributed evenly. Then, the particle fragments were sieved layer by layer. It was confirmed that the particles and loading strength have great influences on fractures of granular materials.

Highlights

Vallejo et al [34] conducted particle compression crushing tests using the same size glass beads and simulated the experimental process by the discrete element methods, the results show that the granular material forms a new system, and the particle size distribution in the new system presents a natural fractal feature. e above studies analyzed the mechanical behavior of granular material composed of the same size particles; the particle size distribution is one of the important parameters that describe the composition of granular material, which directly affects the constitutive relation of granular material [35]
A systematic method was proposed to measure the mechanical behavior of granular material
A systematic method was proposed to measure the mechanical behavior of granular material, and the experiments were performed with different sizes and gradation particles. e overall load, local load, overall displacement, and fragment size distribution were analyzed and compared, and the main conclusions are shown below: (1) During the loading, the fracture and flow of the particles lead to repeated loading-unloadingreloading phenomenon, and the overall load rises in a fluctuating manner

Summary

Introduction

Granular materials consist of discrete particles and surrounding voids. e mechanical behaviors of granular materials are involved in many engineering fields, such as mining engineering, mineral processing engineering, blasting engineering, hydraulic engineering, railway engineering, and so on. e flows and fractures of granular materials under external loading are very common and play important roles in these related engineering fields, such as ore crushing, mechanical behaviors of rockfill dam, the flows and fractures of railroad slag, and so on. Vallejo et al [34] conducted particle compression crushing tests using the same size glass beads and simulated the experimental process by the discrete element methods, the results show that the granular material forms a new system, and the particle size distribution in the new system presents a natural fractal feature. Due to the large number and fluidity of particles, it is difficult to measure the contact force between particles by experimental methods; with the development of computers, numerical simulation methods have become an effective way to study the mechanical behavior of granular material. Erefore, systematic experimental studies on granular materials with different sizes and gradations are important for identifying the flow and fragmentation mechanism of granular materials.

Experiment Method

Experimental Result and Analysis

Fragment Size Distribution

Findings

Conclusions