Study on the cross-interface propagation characteristics of hydraulic fractures in composite hard roofs and migration law of overlying strata

Study on the cross-interface propagation characteristics of hydraulic fractures in composite hard roofs and migration law of overlying strata | 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 Article Study on the cross-interface propagation characteristics of hydraulic fractures in composite hard roofs and migration law of overlying strata Kaige Zheng This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7675279/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 12 You are reading this latest preprint version Abstract While hydraulic fracturing is considered an effective method for mitigating large-area suspended hard and thick roof problems, the mechanisms of fracture propagation orientation and the evolution of overburden migration remain insufficiently understood. To address this gap in literature, this study investigated the cross-layer propagation characteristics of hydraulic fractures under various conditions through numerical simulations. Based on the simulation results, similar experimental studies were conducted to explore the migration patterns of the overlying strata in mining areas under various pre-splitting conditions of composite hard roofs. The experimental findings showed that the direction of the maximum principal stress determines the direction of fracture propagation and that the extent of fracture propagation increases with the increase in the differential principal stress. Hydraulic fractures could not penetrate the layers when the joint bonding strength was low (0.5). When the spacing between the fracturing segments was less than 3 m, the initiation of the second hydraulic fracture had a compressive effect on the first one. Hydraulic fracturing reduced the periodic weighting step distance, the overhanging area, and the degree of stress concentration. Moreover, the pre-splitting effect was significant on both the upper and lower hard roofs. Specifically, under hydraulic fracturing, the periodic weighting step distances under working conditions 1 to 4 were 10.3, 8.2, 9.2, and 7.5 cm, respectively. Under these working conditions, the “square” positions occurred when the working face advanced to the 11th, 13th, 12th, and 14th periodic weighting, and the corresponding stress concentration coefficients were 2.72, 2.57, 2.05, and 1.89, respectively. This study provides significant insights into the selection of the hydraulic fracturing process and its parameters under similar production conditions. Physical sciences/Energy science and technology Physical sciences/Engineering Earth and environmental sciences/Natural hazards Earth and environmental sciences/Solid earth sciences hydraulic fracturing roof overhanging fracture propagation similar simulation Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 23 Mar, 2026 Reviews received at journal 18 Mar, 2026 Reviews received at journal 13 Mar, 2026 Reviews received at journal 25 Feb, 2026 Reviewers agreed at journal 15 Feb, 2026 Reviewers agreed at journal 12 Feb, 2026 Reviewers agreed at journal 10 Feb, 2026 Reviewers invited by journal 10 Feb, 2026 Editor invited by journal 24 Oct, 2025 Editor assigned by journal 23 Oct, 2025 Submission checks completed at journal 23 Oct, 2025 First submitted to journal 22 Sep, 2025 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. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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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-7675279","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":590334483,"identity":"82445ecc-459c-4156-8815-1bcf0bf615db","order_by":0,"name":"Kaige Zheng","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABEUlEQVRIiWNgGAWjYDACCRBxgIGHgYH5AESEmXgtbAkMDAkkaAECHgOIFkJAfnbzsYdfztjJyLv3fPzw84eN3YbjzM8eMNTYROPSwjjnWLqxzI1kHsMzZzdL9iSkJc9sZjM3YDiWltuAQwuzRI6ZtMQHZh7DGbnbmBkSDifzMzOYSTA2HMaphU0i/xtQSz2P4fw3z4Ba/iezMbN/w6uFRyKHTfLDjcM88hI8bEAtB+z4mXnw2yIhkWYmzXDmOI8BT5qxZE9acoJkM0+ZRAIev8jPSH4m+eNYtb18++GHH4ABZm9w/vg2iQ81Nji1gIMAGI8MBgcgnESwygQ8ykGA8QfIOqih9gQUj4JRMApGwQgEAALSVKXCd6QVAAAAAElFTkSuQmCC","orcid":"","institution":"China Coal Technology and Engineering Group Corp Xi'an Research Insititute","correspondingAuthor":true,"prefix":"","firstName":"Kaige","middleName":"","lastName":"Zheng","suffix":""}],"badges":[],"createdAt":"2025-09-22 12:38:46","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7675279/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7675279/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":102747652,"identity":"5ba220f3-400f-4724-9aef-df148e9f34b2","added_by":"auto","created_at":"2026-02-16 09:05:08","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1307969,"visible":true,"origin":"","legend":"","description":"","filename":"Manuscript3.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7675279/v1_covered_50d2e2c5-928b-4bbf-84ea-7af064798226.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Study on the cross-interface propagation characteristics of hydraulic fractures in composite hard roofs and migration law of overlying strata","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"hydraulic fracturing, roof overhanging, fracture propagation, similar simulation","lastPublishedDoi":"10.21203/rs.3.rs-7675279/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7675279/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eWhile hydraulic fracturing is considered an effective method for mitigating large-area suspended hard and thick roof problems, the mechanisms of fracture propagation orientation and the evolution of overburden migration remain insufficiently understood. To address this gap in literature, this study investigated the cross-layer propagation characteristics of hydraulic fractures under various conditions through numerical simulations. Based on the simulation results, similar experimental studies were conducted to explore the migration patterns of the overlying strata in mining areas under various pre-splitting conditions of composite hard roofs. The experimental findings showed that the direction of the maximum principal stress determines the direction of fracture propagation and that the extent of fracture propagation increases with the increase in the differential principal stress. Hydraulic fractures could not penetrate the layers when the joint bonding strength was low (0.5). When the spacing between the fracturing segments was less than 3 m, the initiation of the second hydraulic fracture had a compressive effect on the first one. Hydraulic fracturing reduced the periodic weighting step distance, the overhanging area, and the degree of stress concentration. Moreover, the pre-splitting effect was significant on both the upper and lower hard roofs. Specifically, under hydraulic fracturing, the periodic weighting step distances under working conditions 1 to 4 were 10.3, 8.2, 9.2, and 7.5 cm, respectively. Under these working conditions, the \u0026ldquo;square\u0026rdquo; positions occurred when the working face advanced to the 11th, 13th, 12th, and 14th periodic weighting, and the corresponding stress concentration coefficients were 2.72, 2.57, 2.05, and 1.89, respectively. 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