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Abstract Triaxial compression tests and acoustic emission(AE) monitoring were carried out for Jiangxi red sandstone using servo-controlled rock mechanical test system；its permeability was tested with gas at the same time. The rock permeability rules and AE characteristics under the failure processes of three types of stress paths，i.e. conventional triaxial compression，unloading confining pressure at the pre-peak and post-peak strength，were studied. The experimental results indicate that：(1) The peak strength of rock samples increases gradually with the increase of effective confining pressure，which means that the peak strength is sensitive to effective confining pressure. (2) In conventional triaxial compression test，the permeability curves fall slightly before yield and then increase dramatically after yield and suffer a slight pullback at the post-peak strain softening stage. The permeability trends before unloading of confining pressure at the pre-peak and post-peak strength are basically the same as that under conventional triaxial compression process. The curves both grow more rapidly after unloading. (3) Under the same loading path，changes of confining pressure only affect the relative values of permeability during all stages，but not affect the trends of the curves. (4) In conventional triaxial compression test，AE activity is relatively quiet prior to yield，and begins to liven up after yield then tends to be quiet again at the post-peak strain softening stage. Shortly after unloading of confining pressure at the pre-peak strength，AE activity appears extremely active and dense. The strength of signal is relative higher and reaches an obvious peak value. The AE law in the test process of unloading confining pressure at the post-peak strength is similar to that in the process of conventional triaxial compression test. (5) With the increase of confining pressure，rock appears more ductility and less brittleness in failure process. At the same confining pressure，rock presents most brittleness and reaches highest broken degree. (6) The dilatancy points of rock samples are close to the minimums of permeability. There is a well corresponding between volumetric strain and permeability with axial strain. The intensive stages of AE activity emerge after dilatancy. It is shown that there are some links among permeability，AE，stress and (volumetric) strain.
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Received: 22 March 2013
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2014, Vol. 33 
