矿业科学学报 (Jun 2020)
Effects of deformation rate and hydrated condition on the mechanical property of sandstone
Abstract
According to a set of uniaxial compression experiments of sandstone, effects of deformation rate and hydrated condition on the compressive strength, elastic modulus, post-peak strain and acoustic emission(AE) characteristics were explored.A one-dimensional constitutive model by considering the effects of deformation rate and hydrated condition for sandstone is established and verified by defining s series of strengthening and weakening factors.The results show that:① Stress-strain curve of dry rock includes elastic stage, weak plastic stage and broken stage while the compaction stage, shorter elastic stage and longer plastic stage appear for water-saturated sandstone.② Deformation rate enlarges the compressive strength of sandstone.The deformation-rate factor of strength increases with the increasing deformation rate.Water has weakening effect on the compressive strength of sandstone, and the difference of compressive strength between the dry and saturated sandstone decreases gradually with the increasing deformation rate.③ The elastic modulus of dry and saturated sandstone increases linearly with the deformation rate.Water has weakening effect on the elastic modulus.The elastic modulus of saturated sandstone is lower than that of dry sandstone, and the weakening factor undergoes little change at different deformation rates.④ Deformation rate has little effect on the post-peak strain of sandstone, the post-peak strain of saturated sandstone is much higher than that of dry sandstone and the hydraulic strengthening factor of post-peak strain is not sensitive to the deformation rate.⑤ Cumulated AE energy increases with deformation rate, cumulated AE energy advances for dry specimen and postpones for water-saturated stone.Accumulation of energy for water-saturated specimen is 3-5 times that of dry specimens.
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