The changes in pore characteristics and mechanical properties of coal rock of water-saturated coal and rock after freeze-thaw cycles

The changes in pore characteristics and mechanical properties of coal rock of water-saturated coal and rock after freeze-thaw cycles | 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 The changes in pore characteristics and mechanical properties of coal rock of water-saturated coal and rock after freeze-thaw cycles Ma Heng, Tang Pengyang, Wang Xiaoqi, ke Gao This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6930648/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 Liquid nitrogen freeze-thaw has a positive effect on increasing the permeability of coal and rock.In order to study the pore characteristics and mechanical characteristics of water-saturated coal rock under liquid nitrogen cycle freezing and thawing, nuclear magnetic resonance, triaxial loading and seepage experiments were carried out on water-saturated frozen coal rock.The results show that: (1) After the freeze-thaw cycles, various types of pores in the coal and rock gradually develop. This is because liquid nitrogen freeze-thaw can promote the generation and development of micro-pores, and expand and fuse them into medium and large pores, thereby forming a fracture network; (2) After five freeze-thaw cycles, the porosity of the coal and rock increased from 1.089% to 2.571%, and the permeability increased from 0.771 mD to 19.884 mD. Compared with the initial freeze-thaw, the number of adsorption pores in the coal and rock increased from 1.15 times to 2.82 times, and the number of seepage pores increased from 1.80 times to 6.23 times; (3) After multiple freeze-thaw cycles, the internal fracture structure of the coal and rock gradually expands and fuses to form new fractures. The generation of new fractures releases the bound water in the adsorption pores to larger pores and transforms it into free water, resulting in a significant increase in the porosity and permeability of the coal and rock; (4) With the increase in the number of freeze-thaw cycles, the rate of energy accumulation in the coal and rock before the peak gradually decreases. Earth and environmental sciences/Environmental sciences Physical sciences/Materials science Water-saturated coal liquid nitrogen freeze-thaw pore structure coalbed methane low field NMR rock mechanics 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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This is because liquid nitrogen freeze-thaw can promote the generation and development of micro-pores, and expand and fuse them into medium and large pores, thereby forming a fracture network; (2) After five freeze-thaw cycles, the porosity of the coal and rock increased from 1.089% to 2.571%, and the permeability increased from 0.771 mD to 19.884 mD. Compared with the initial freeze-thaw, the number of adsorption pores in the coal and rock increased from 1.15 times to 2.82 times, and the number of seepage pores increased from 1.80 times to 6.23 times; (3) After multiple freeze-thaw cycles, the internal fracture structure of the coal and rock gradually expands and fuses to form new fractures. 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