自然科学版 英文版
自然科学版 英文版
自然科学版 英文版

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中南大学学报(英文版)

Journal of Central South University

Vol. 25    No. 8    August 2018

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Experimental investigation on deformation characteristics and permeability evolution of rock under confining pressure unloading conditions
CHEN Xu(陈旭)1, TANG Chun-an(唐春安)1, 2, YU Jin(俞缙)3,ZHOU Jian-feng(周建烽)3, CAI Yan-yan(蔡燕燕)3

1. School of Resources and Civil Engineering, Northeastern University, Shenyang 110819, China;
2. School of Civil and Hydraulic Engineering, Dalian University of Technology, Dalian 116024, China;
3. Fujian Research Center for Tunneling and Urban Underground Space Engineering, Huaqiao University, Xiamen 361021, China

Abstract:Deformation behavior and hydraulic properties of rock are the two main factors that influence safety of excavation and use of rock engineering due to in situ stress release. The primary objective of this study is to explore deformation characteristics and permeability properties and provide some parameters to character the rock under unloading conditions. A series of triaxial tests with permeability and acoustic emission signal measurement were conducted under the path of confining pressure unloading prior to the peak stress. Deformation behavior and permeability evolution in the whole stress–strain process based on these experimental results were analyzed in detail. Results demonstrate that, under the confining pressure unloading conditions, a good correspondence relationship among the stress–axial strain curve, permeability–axial strain curve and acoustic emission activity pattern was obtained. After the confining pressure was unloaded, the radial strain grew much faster than the axial strain, which induced the volumetric strain growing rapidly. All failures under confining pressure unloading conditions featured brittle shear failure with a single macro shear rupture surface. With the decrease in deformation modulus during the confining pressure unloading process, the damage variable gradually increases, indicating that confining pressure unloading was a process of damage accumulation and strength degradation. From the entire loading and unloading process, there was a certain positive correlation between the permeability and volumetric strain.

 

Key words: unloading rock mechanics; permeability evolution; triaxial experiment; acoustic emission; sandstone

中南大学学报(自然科学版)
  ISSN 1672-7207
CN 43-1426/N
ZDXZAC
中南大学学报(英文版)
  ISSN 2095-2899
CN 43-1516/TB
JCSTFT
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