{"title":"Dynamic and static compaction methods deriving different strain evolutions under cyclic loading for silt and its microscopic interpretation","authors":"","doi":"10.1016/j.trgeo.2024.101378","DOIUrl":null,"url":null,"abstract":"<div><p>To satisfy the economic requirements and reduce the impact to the surrounding buildings and underground structures, the dynamic compaction (heavy tamping) and static compaction are combined used in the soil filling for airport subgrade. Despite compaction the subgrades in the same degree of compaction, the subgrades filled by dynamic and static compaction method show different increase potential in the permanent strain under cyclic loading, which then further result in the differential settlement and safety problems. This study firstly investigated the<!--> <!-->compaction characteristics under static compaction and different dynamic compaction scheme, during which the static and dynamic compaction strain and stress evolutions were monitored. The cyclic triaxial tests were then performed to investigate the sample preparation method derived difference in permanent strain under cyclic loading. Furthermore, to provide a microscopic interpretation to this difference, the pore size distributions of the silt samples based on mercury intrusion porosimetry (MIP) test and the internal particle contact stresses from discrete element method (DEM) simulation were respectively explored. The main conclusions are as follows: (1) The dynamic compaction processes can be divided into rapid and slow compaction strain stages determined by strain growth rate and compaction numbers, which further influences the homogeneity of soil samples; (2) The statically compacted samples have more significant permanent strain than the dynamic ones due to the localized stress concentration and different pore microstructures; the permanent strain increases with dynamic compaction energy until a stable stage is reached. (3) The MIP results show that the dynamic compaction transforms<!--> <!-->the macropores into mesopores; the higher compaction energy enhances this transforming effect but results in a decrease in the overall homogeneity.</p></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":null,"pages":null},"PeriodicalIF":4.9000,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Transportation Geotechnics","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2214391224001995","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ENGINEERING, CIVIL","Score":null,"Total":0}
引用次数: 0
Abstract
To satisfy the economic requirements and reduce the impact to the surrounding buildings and underground structures, the dynamic compaction (heavy tamping) and static compaction are combined used in the soil filling for airport subgrade. Despite compaction the subgrades in the same degree of compaction, the subgrades filled by dynamic and static compaction method show different increase potential in the permanent strain under cyclic loading, which then further result in the differential settlement and safety problems. This study firstly investigated the compaction characteristics under static compaction and different dynamic compaction scheme, during which the static and dynamic compaction strain and stress evolutions were monitored. The cyclic triaxial tests were then performed to investigate the sample preparation method derived difference in permanent strain under cyclic loading. Furthermore, to provide a microscopic interpretation to this difference, the pore size distributions of the silt samples based on mercury intrusion porosimetry (MIP) test and the internal particle contact stresses from discrete element method (DEM) simulation were respectively explored. The main conclusions are as follows: (1) The dynamic compaction processes can be divided into rapid and slow compaction strain stages determined by strain growth rate and compaction numbers, which further influences the homogeneity of soil samples; (2) The statically compacted samples have more significant permanent strain than the dynamic ones due to the localized stress concentration and different pore microstructures; the permanent strain increases with dynamic compaction energy until a stable stage is reached. (3) The MIP results show that the dynamic compaction transforms the macropores into mesopores; the higher compaction energy enhances this transforming effect but results in a decrease in the overall homogeneity.
期刊介绍:
Transportation Geotechnics is a journal dedicated to publishing high-quality, theoretical, and applied papers that cover all facets of geotechnics for transportation infrastructure such as roads, highways, railways, underground railways, airfields, and waterways. The journal places a special emphasis on case studies that present original work relevant to the sustainable construction of transportation infrastructure. The scope of topics it addresses includes the geotechnical properties of geomaterials for sustainable and rational design and construction, the behavior of compacted and stabilized geomaterials, the use of geosynthetics and reinforcement in constructed layers and interlayers, ground improvement and slope stability for transportation infrastructures, compaction technology and management, maintenance technology, the impact of climate, embankments for highways and high-speed trains, transition zones, dredging, underwater geotechnics for infrastructure purposes, and the modeling of multi-layered structures and supporting ground under dynamic and repeated loads.