Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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中国有色金属学报(英文版)

Transactions of Nonferrous Metals Society of China

Vol. 25    No. 4    April 2015

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Microscopic damage and dynamic mechanical properties of rock under freeze-thaw environment
Ke-ping ZHOU1,2, Bin LI1,2, Jie-lin LI1,2, Hong-wei DENG1,2, Feng BIN1,2

1. School of Resources and Safety Engineering, Central South University, Changsha 410083, China;
2. Mining Engineering Technology Research Center for High Altitude Cold Region,
Central South University, Changsha 410083, China

Abstract:For understanding the rock microscopic damage and dynamic mechanical properties subjected to recurrent freeze-thaw cycles, experiments for five groups of homogeneous sandstone under different freeze-thaw cycles were conducted. After freeze- thaw, nuclear magnetic resonance (NMR) tests and impact loading tests were carried out, from which microscopic damage characteristics of sandstone and dynamic mechanical parameters were obtained. The results indicate that the porosity increases with the increase of cycle number, the rate of porosity growth descends at the beginning of freeze-thaw, yet accelerates after a certain number of cycles. The proportion of pores with different sizes changes dynamically and the multi-scale distribution of pores tends to develop on pore structure with the continuing impact of freeze-thaw and thawing. Dynamic compressive stress-strain curve of sandstone undergoing freeze-thaw can be divided into four phases, and the phase of compaction is inconspicuous compared with the static curve. Elastic modulus and dynamic peak intensity of sandstone gradually decrease with freeze-thaw cycles, while peak strain increases. The higher the porosity is, the more serious the degradation of dynamic intensity is. The porosity is of a polynomial relationship with the dynamic peak intensity.

 

Key words: rock; freeze-thaw cycle; nuclear magnetic resonance (NMR); pore structure; dynamic mechanical property; dynamic compression; stress-strain curve

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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