Study on mechanical and energy characteristics of sandstone under variable loading rate conditions
Uniaxial compression tests on sandstone samples under different loading rates were conducted,and the mechanical and energy characteristics of sandstone under variable loading rates were analyzed.The test results showed that the peak strength and elastic modu-lus of sandstone increased as a exponential function with the increase of loading rate.The energy absorption,storage,and dissipation pat-terns of sandstone during different stages of deformation were analyzed.Under variable loading rates,the energy and axial compression curves of sandstone showed similar variation characteristics.More than 70％of the total energy absorbed by sandstone before peak was accumulated in the form of releasable elastic properties,while less than 30％of the total energy was dissipated by various internal defects during compaction,slip,and plastic stages of new microcrack.The fitting of the total energy absorbed before the peak and the released e-lastic energy of the sample showed a linear growth relationship with the loading rate.The relationship curves between Ue/U,Ud/U,stress ratio,and axial strain were obtained,and they were divided into three stages of change:the primary fracture compression closure stage(σ1/σmax＜0.25),sandstone continuously absorbs energy stage(0.25＜σ1/σmax＜0.8)and energy dissipation stage(σ1/σmax＞0.8).The higher the loading rate,the greater the damage stress and Ue/U,and the smaller the Ud/U.
万方数据
维普
