Effects of specimen size on linear energy storage and dissipation laws of red sandstone under uniaxial compression

摘要

Size effect is a project that cannot be ignored in rock mechanics. To investigate the size effect on the energy distribution andevolution laws, several groups of uniaxial compression tests and single-cycle loading–unloading uniaxial compression tests wereperformed on red sandstone specimens of different sizes (diameters of 25, 37, 50, 75, and 100 mm; a constant length-to-diameterratio of 2.0) using the INSTRON 1346 test system. Experimental results show that mechanical properties are influenced byspecimen size while failure mode has no significant variation for different diameter specimens. Strain energy parameters(input strain energy, elastic strain energy, and dissipated strain energy) under each unloading stress level were calculatedby integration based on the stress–strain curves. The input strain energy, elastic strain energy, and dissipated strain energynonlinearly increase with actual unloading stress levels, expressed as unified quadratic function relationships. Furthermore,the elastic strain energy and dissipated strain energy have linear relationships with the input strain energy. Through analyzingcoefficients of variation of common parameters, it was found that the energy storage capacity of rock was not sensitive tothe specimen size, and therefore, the energy storage coefficient could be considered an essential property of rock materials.