Study on type I fracture characteristics and double K toughness model testing of anchored sandstone

Study on type I fracture characteristics and double K toughness model testing of anchored sandstone | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Study on type I fracture characteristics and double K toughness model testing of anchored sandstone Tong-bin Zhao, Wei Zhang, Ming-lu Xing This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3890702/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Engineering rock masses prone to type I tensile cracks due to excavation unloading can be reinforced with anchor rods to increase the proportion of stable fracture stage and reduce the probability of brittle failure. However, based on the traditional strength analysis method, the relationship of σ - ε is difficult to fully explain. Therefore, it holds crucial engineering and theoretical value to explore the failure mechanism of anchored rock based on the characteristics of fracture mechanics. In this paper, the fracture toughness of rock with different bolt crack relative positions and preloads is tested through speckle light measurement. The double K fracture criterion is introduced, and the mechanism of crack arrest and toughening of bolts is discussed based on the net stress intensity factor theory. The research results indicate that the closing force generated by the lateral action of the anchor rod significantly reduces the range of rock strain localization. While it has a limited effect on delaying rock cracking, it can effectively delay crack propagation and intersection. The initiation and instability fracture toughness of rocks show a logarithmic increasing trend with the shortening of the relative position between anchor bolts and cracks and the increase of preload. Increasing the net stress intensity factor at the crack tip of the bolt improves the rock crack initiation and unstable fracture toughness. After anchoring, the rock crack initiation and unstable fracture toughness increased by 90% and 130%, respectively. The length and time of the stable crack growth stage increased by 50% and 70%, respectively. Anchored rock type I fracture double K fracture toughness crack propagation three point bending Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-3890702","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":268950380,"identity":"aa270042-71c1-4c76-ac0a-7f98adcb1db6","order_by":0,"name":"Tong-bin Zhao","email":"","orcid":"","institution":"Shandong University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Tong-bin","middleName":"","lastName":"Zhao","suffix":""},{"id":268950381,"identity":"91ea48e1-9ecb-4f9f-bed2-de63b8e3e982","order_by":1,"name":"Wei Zhang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAwUlEQVRIiWNgGAWjYBACNmbm4x8+/qup72dvIFILHztbGuMMtmOMM3sOEKlFjp/HjJmDjZlxw40Eoh3GYPaYgQdI3Xy88QZDjU00MVrSjQskZNgYZ6cVWzAcS8ttIELLAekZBmw8zNI5ZhKMDYeJ0cLYIM2TwCzBJnmGaC3MbNI8B5gNeCR4iNbCxmw4s+FYggQP0C8JxPhFvv/8xwcfG2oS7I8f3njjQ40NYS3IwEAigRTlEC2k6hgFo2AUjIKRAQDtbzZ46FzdVwAAAABJRU5ErkJggg==","orcid":"","institution":"Liaocheng University","correspondingAuthor":true,"prefix":"","firstName":"Wei","middleName":"","lastName":"Zhang","suffix":""},{"id":268950382,"identity":"0c5f6925-fb3a-4815-8667-4803af8398a0","order_by":2,"name":"Ming-lu Xing","email":"","orcid":"","institution":"Shandong University of Science and Technology","correspondingAuthor":false,"prefix":"","firstName":"Ming-lu","middleName":"","lastName":"Xing","suffix":""}],"badges":[],"createdAt":"2024-01-23 09:59:23","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3890702/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3890702/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":50190059,"identity":"ecda3c5c-8bbd-4446-a5fe-bae2a3adfe23","added_by":"auto","created_at":"2024-01-25 22:22:25","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1253426,"visible":true,"origin":"","legend":"","description":"","filename":"Manam.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3890702/v1_covered_c3c4d7e0-6710-4185-86be-adbcac03d5fb.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Study on type I fracture characteristics and double K toughness model testing of anchored sandstone","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Anchored rock, type I fracture, double K fracture toughness, crack propagation, three point bending","lastPublishedDoi":"10.21203/rs.3.rs-3890702/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3890702/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eEngineering rock masses prone to type I tensile cracks due to excavation unloading can be reinforced with anchor rods to increase the proportion of stable fracture stage and reduce the probability of brittle failure. However, based on the traditional strength analysis method, the relationship of \u003cem\u003eσ\u003c/em\u003e-\u003cem\u003eε\u003c/em\u003e is difficult to fully explain. Therefore, it holds crucial engineering and theoretical value to explore the failure mechanism of anchored rock based on the characteristics of fracture mechanics. In this paper, the fracture toughness of rock with different bolt crack relative positions and preloads is tested through speckle light measurement. The double \u003cem\u003eK\u003c/em\u003e fracture criterion is introduced, and the mechanism of crack arrest and toughening of bolts is discussed based on the net stress intensity factor theory. The research results indicate that the closing force generated by the lateral action of the anchor rod significantly reduces the range of rock strain localization. While it has a limited effect on delaying rock cracking, it can effectively delay crack propagation and intersection. The initiation and instability fracture toughness of rocks show a logarithmic increasing trend with the shortening of the relative position between anchor bolts and cracks and the increase of preload. Increasing the net stress intensity factor at the crack tip of the bolt improves the rock crack initiation and unstable fracture toughness. After anchoring, the rock crack initiation and unstable fracture toughness increased by 90% and 130%, respectively. 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