{"title":"Compaction and re-crushing characteristics of sandstone granules with different gradations under cyclic loading","authors":"","doi":"10.1016/j.apt.2024.104611","DOIUrl":null,"url":null,"abstract":"<div><p>Under the influence of multiple mining of coal seams, the granules structure formed by the mixing of different grain sizes exists in the collapse zone, and its compaction and re-crushing characteristics become a factor influencing the deformation and movement of the overlying rock layer. Therefore, the characteristics of sandstone granules with different gradations under cyclic loading were investigated in this manuscript. It is shown that the strain of sandstone granules increases with the increase of gradation index <em>n</em>, the dissipation energy of particle movement and crushing shows an increasing trend, and its porosity decreases with the increase of axial stress as a whole. At the early stage of stress loading, the high-gradation sandstone granules have high compression space and crushing potential due to larger size particles, the porosity declines the fastest, the compression modulus increases sharply, and the sandstone granules is compacted rapidly at this stage. When the stress exceeds a certain range, the energy density changes and the porosity reduction of the higher-gradation granules increases, and the larger size particles in the higher-gradations granules samples are broken down into small-size particles. At the same time, the amount of energy density changes and porosity attenuation of the high-gradations sandstone granules increases, the compressive modulus increases again at this stage, the position of the granules particles moves and the distribution is re-distributed, and the granules particles are more compact after the re-distribution, which corresponds to the higher re-distribution of the high-gradations granules samples. Under the external disturbance load, the sandstone granules show the characteristics of “three stages”: pore compression period, elastic deformation period, and crushing and reorganization period. The results of this study can provide theoretical support for revealing the deformation and movement mechanism of the rock mass in the collapse zone under multiple mining.</p></div>","PeriodicalId":7232,"journal":{"name":"Advanced Powder Technology","volume":null,"pages":null},"PeriodicalIF":4.2000,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Advanced Powder Technology","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0921883124002875","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENGINEERING, CHEMICAL","Score":null,"Total":0}
引用次数: 0
Abstract
Under the influence of multiple mining of coal seams, the granules structure formed by the mixing of different grain sizes exists in the collapse zone, and its compaction and re-crushing characteristics become a factor influencing the deformation and movement of the overlying rock layer. Therefore, the characteristics of sandstone granules with different gradations under cyclic loading were investigated in this manuscript. It is shown that the strain of sandstone granules increases with the increase of gradation index n, the dissipation energy of particle movement and crushing shows an increasing trend, and its porosity decreases with the increase of axial stress as a whole. At the early stage of stress loading, the high-gradation sandstone granules have high compression space and crushing potential due to larger size particles, the porosity declines the fastest, the compression modulus increases sharply, and the sandstone granules is compacted rapidly at this stage. When the stress exceeds a certain range, the energy density changes and the porosity reduction of the higher-gradation granules increases, and the larger size particles in the higher-gradations granules samples are broken down into small-size particles. At the same time, the amount of energy density changes and porosity attenuation of the high-gradations sandstone granules increases, the compressive modulus increases again at this stage, the position of the granules particles moves and the distribution is re-distributed, and the granules particles are more compact after the re-distribution, which corresponds to the higher re-distribution of the high-gradations granules samples. Under the external disturbance load, the sandstone granules show the characteristics of “three stages”: pore compression period, elastic deformation period, and crushing and reorganization period. The results of this study can provide theoretical support for revealing the deformation and movement mechanism of the rock mass in the collapse zone under multiple mining.
在煤层多次开采的影响下,塌陷区存在不同粒度混合形成的颗粒结构,其压实和再破碎特性成为影响上覆岩层变形和移动的因素。因此,本手稿研究了不同级配砂岩颗粒在循环荷载作用下的特征。结果表明,砂岩颗粒的应变随级配指数 n 的增大而增大,颗粒运动和破碎的耗散能呈增大趋势,其孔隙率随轴向应力的增大而整体减小。在应力加载初期,高级配砂岩颗粒由于粒径较大,具有较高的压缩空间和破碎潜能,孔隙率下降最快,压缩模量急剧增大,该阶段砂岩颗粒被快速压实。当应力超过一定范围时,能量密度发生变化,较高级配颗粒的孔隙率下降速度加快,较高级配颗粒样品中的较大尺寸颗粒被破碎成小尺寸颗粒。同时,高分级砂岩颗粒的能量密度变化量和孔隙率衰减量增大,此阶段压缩模量再次增大,颗粒位置移动,重新分布,重新分布后的颗粒颗粒更加紧密,这与高分级颗粒样品的高重新分布相对应。在外部扰动荷载作用下,砂岩颗粒呈现出孔隙压缩期、弹性变形期、破碎重组期的 "三期 "特征。该研究结果可为揭示多次开采下塌陷区岩体的变形和运动机理提供理论支持。
期刊介绍:
The aim of Advanced Powder Technology is to meet the demand for an international journal that integrates all aspects of science and technology research on powder and particulate materials. The journal fulfills this purpose by publishing original research papers, rapid communications, reviews, and translated articles by prominent researchers worldwide.
The editorial work of Advanced Powder Technology, which was founded as the International Journal of the Society of Powder Technology, Japan, is now shared by distinguished board members, who operate in a unique framework designed to respond to the increasing global demand for articles on not only powder and particles, but also on various materials produced from them.
Advanced Powder Technology covers various areas, but a discussion of powder and particles is required in articles. Topics include: Production of powder and particulate materials in gases and liquids(nanoparticles, fine ceramics, pharmaceuticals, novel functional materials, etc.); Aerosol and colloidal processing; Powder and particle characterization; Dynamics and phenomena; Calculation and simulation (CFD, DEM, Monte Carlo method, population balance, etc.); Measurement and control of powder processes; Particle modification; Comminution; Powder handling and operations (storage, transport, granulation, separation, fluidization, etc.)