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Abstract A self-made observation testing apparatus of micro- and meso-scopic mechanics and deformation of tailings is used to study the nonlinear characteristics of deformation evolution for meso-scopic structure of tailings under loading，including directionality of internal stress，variation rule of void ratio，fractal characteristics of meso-scopic pore structure，deformation evolution rule of pore structure under loading，etc. The results show as follows：(1) The internal stress of tailing specimen has obvious direction characteristics，because the vertical stress which is slightly lower than load increases nonlinearly and horizontal stress which is far lower than load increases linearly with the increase in load. (2) The void ratio of tailings，which changes a lot，decreases nonlinearly in different layers. The change in void ratio for lower layer lags behind that for upper layer；and both will finally reduce to the same value. (3) The concept of section void ratio of meso-scopic structure of tailings is put forward. For the same section，the section void ratio has linearly positive correlation with void ratio of the same layer. (4) The meso-scopic structure of tailings has obvious perimeter-area fractal characteristics. The fractal dimensions are 1.424–1.537；and its value has logarithmically negative correlation with section void ratio obviously. (5) The section void ratio decreases under the effect of loading despite tiny rebound，the fractal dimension of perimeter-area increases at stages under the effect of loading，followed by small amplitude reduction at each stage. The section void ratio and fractal dimension of perimeter-area describing the characteristics of meso-scopic structure of tailings are put forward，which is very important to quantitatively study meso-scopic structure characteristics and mechanical properties of tailings dams.
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Received: 20 January 2011
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2011, Vol. 30 
