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Abstract The fatigue damage of granite under cyclic fatigue load are caused by the propagation and coalescent of cracks at mesoscale，so it is of important theoretical value and practical significance to understand the fatigue properties of rock by experimental research on meso fatigue damage of granite. The whole test scheme included two parts as follows：the uniaxial different frequencies cyclic loading and unloading tests and the meso-damage quantification tests based on SEM. The uniaxial different frequencies cyclic loading and unloading tests on granite were done on the RMT–150B multi-function automatic rigid rock servo material testing machine. Sine wave cyclic loads with stress amplitude of 10 MPa and seven different frequencies of 0.01，0.02，0.05，0.10，0.20，0.50 and 1.00 Hz were adopted as dynamic disturbance. A great deal of mesostructural images of granite has been obtained by means of scanning electron microscope(SEM). It is shown that when the cyclic frequency is relative low，intergranular cracks are the main forms of meso fatigue damage of crystals. When the frequency is relatively high，intergranular cracks are the main forms of meso fatigue damage of quartz and mica crystal and the forms of meso fatigue damage of feldspar are intergranular cracks，transgranular cracks and grain cracks. The azimuth of intergranular cracks and grain cracks tends to the axial direction of cyclic load. But the azimuth of transgranular cracks appeares irregular. And the major meso fatigue damage is intragranular cracks.
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Received: 23 July 2010
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2011, Vol. 30 
