{"title":"Damage zone around underground opening caused by combined blast loading and initial stress unloading","authors":"Rui Zhao, Ming Tao, Murat Karakus","doi":"10.1016/j.ijrmms.2024.106018","DOIUrl":null,"url":null,"abstract":"The formation of an Excavation Damaged Zone (EDZ) is a common issue in mining and other geotechnical engineering fields, which impacts the stability of surrounding rock mass. The excavation of deep, stressed rock mass induces stress redistribution and propagates stress waves that form an EDZ around the excavation. Modelling the complex processes of stress relief and adjustment in anisotropic stress states is challenging but essential for understanding EDZ formation mechanisms and optimizing blast design. In this study, we derive the stress response in the surrounding rock mass caused by the initial stress unloading and blast loading in arbitrary stress states. This is achieved by the application of modal superposition and Laplace transform. The impacts of the unloading period, blasting amplitude, and stress state were studied. Then a series of Finite Element Method (FEM) numerical simulations were carried out to obtain the EDZ around the opening under pure unloading and combined loading-unloading. The field observations of the distributions of EDZ in underground mining tunnels excavated by blasting were analysed in conjunction with the theoretical and numerical findings. The results showed the extent of the EDZ increases with initial stress, and at lower stress levels, blasting predominantly governs the formation of the EDZ, while at higher stress levels, unloading and stress redistribution prevail. Blast loading was suggested to be the main cause of the Highly Damaged Zone (HDZ), as the unload-induced redistributed stress and blast loading stress were linearly superimposed in the radial and tangential direction, leading to the elevation in the tangential tensile stress and the radial compressive stress in the rock mass near the excavation boundary.","PeriodicalId":54941,"journal":{"name":"International Journal of Rock Mechanics and Mining Sciences","volume":"12 1","pages":""},"PeriodicalIF":7.0000,"publicationDate":"2025-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"International Journal of Rock Mechanics and Mining Sciences","FirstCategoryId":"5","ListUrlMain":"https://doi.org/10.1016/j.ijrmms.2024.106018","RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ENGINEERING, GEOLOGICAL","Score":null,"Total":0}
引用次数: 0
Abstract
The formation of an Excavation Damaged Zone (EDZ) is a common issue in mining and other geotechnical engineering fields, which impacts the stability of surrounding rock mass. The excavation of deep, stressed rock mass induces stress redistribution and propagates stress waves that form an EDZ around the excavation. Modelling the complex processes of stress relief and adjustment in anisotropic stress states is challenging but essential for understanding EDZ formation mechanisms and optimizing blast design. In this study, we derive the stress response in the surrounding rock mass caused by the initial stress unloading and blast loading in arbitrary stress states. This is achieved by the application of modal superposition and Laplace transform. The impacts of the unloading period, blasting amplitude, and stress state were studied. Then a series of Finite Element Method (FEM) numerical simulations were carried out to obtain the EDZ around the opening under pure unloading and combined loading-unloading. The field observations of the distributions of EDZ in underground mining tunnels excavated by blasting were analysed in conjunction with the theoretical and numerical findings. The results showed the extent of the EDZ increases with initial stress, and at lower stress levels, blasting predominantly governs the formation of the EDZ, while at higher stress levels, unloading and stress redistribution prevail. Blast loading was suggested to be the main cause of the Highly Damaged Zone (HDZ), as the unload-induced redistributed stress and blast loading stress were linearly superimposed in the radial and tangential direction, leading to the elevation in the tangential tensile stress and the radial compressive stress in the rock mass near the excavation boundary.
期刊介绍:
The International Journal of Rock Mechanics and Mining Sciences focuses on original research, new developments, site measurements, and case studies within the fields of rock mechanics and rock engineering. Serving as an international platform, it showcases high-quality papers addressing rock mechanics and the application of its principles and techniques in mining and civil engineering projects situated on or within rock masses. These projects encompass a wide range, including slopes, open-pit mines, quarries, shafts, tunnels, caverns, underground mines, metro systems, dams, hydro-electric stations, geothermal energy, petroleum engineering, and radioactive waste disposal. The journal welcomes submissions on various topics, with particular interest in theoretical advancements, analytical and numerical methods, rock testing, site investigation, and case studies.