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论文类型：期刊论文

发表时间：2018-08-01

发表刊物：JOURNAL OF CENTRAL SOUTH UNIVERSITY

收录刊物：SCIE

卷号：25

期号：8

页面范围：1987-2001

ISSN号：2095-2899

关键字：unloading rock mechanics; permeability evolution; triaxial experiment; acoustic emission; sandstone

摘要：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.