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Abstract Scale effect is widely shown in defective materials while scale effect is mainly originated from material heterogeneity. However，most of the scale effect study followed the research results of negative power law of concrete strength. Through microstructure analysis，much difference exists between rock and concrete materials. Limestone was selected for experimental materials. The experiment data about uniaxial compressive strength and stress-strain curves，etc.，were obtained through uniaxial compressive tests. Based on these data，the scale effect and its influential factors for rock materials are analyzed and studied，which are different from the scaling laws of concrete materials. The research results show that the defect levels in limestone materials influence rock strength，its deformation and failure characteristics heavily. An evident representative scale exists in every heterogeneous rock materials and it is closely related with the defect structural level(defect scale itself and the ratio of defect scale to rock samples scale). Scale effect of rock materials is originated from its heterogeneity，not from the friction effect between the ends of rock sample and loading plate.
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Received: 12 April 2012
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2012, Vol. 31 
