6.Study on pre-peak energy and deterioration evolution ofsandstone under freeze - thaw cycles

Abstract:

Study the impact of freezing and thawing on the physical and mechanical properties of rock in facilities affected by cold re-gions in China，especially the energy evolution mechanism of freeze-thaw rocks and to provide theoretical basis for related projects．Taking sandstone as the research object，it was subjected to 0，30，50 and 70 freeze-thaw cycles and then uniaxial compression testswere conducted to obtain stress-strain profiles observed after varying numbers of freeze-thaw cycles． Based on this，the energy evolutioncurves were calculated and a new method for dividing the stress-strain curve into stages is proposed to deeply analyze the energy evolu-tion law． The findings indicate that as the number of freeze-thaw cycles increases，both the uniaxial compressive strength and elasticmodulus of sandstone decrease and the peak strain increases; the total input energy and elastic energy at the peak stress decrease，while the dissipated energy first decreases and then increases; the length of the linear elastic stage decreases． The research results havereference value for the classification of deformation stages and the analysis of deterioration of freeze-thaw sandstone and can provide sci-entific guidance for the construction and maintenance of rock engineering in cold regions．

Keywords: uniaxial compression; freeze-thaw cycle; sandstone; energy evolution