Experimental Study On Dynamic Compressive Mechanical Properties Of Low Temperature Water-bearing Sandstone

With the development of economic construction and the implementation of the western development strategy in our country,many large-scale geotechnical projects have been carried out in cold regions.At present,the study of rock at home and abroad is concentrated at high temperature and normal temperature,the study of frozen rock is less,and most of them are under statics condition,the study of mechanical properties of frozen rock under dynamic load is much more less.Therefore,the study of frozen rock is particularly urgent and important.In this paper,the dynamic impact compression test of rock under different temperature,different loading pressure and different water content is carried out by SHPB test device.The dynamic compressive mechanical properties of low temperature water-bearing sandstone are studied,and the characteristics of energy dissipation are analyzed.The specific contents are as follows:1.The dynamic impact compression test of low temperature water-bearing sandstone samples under 6 different loading rates of 0.3MPa,0.4MPa,0.5MPa,0.6MPa,0.7MPa and 0.8MPa were carried out by SHPB test device.The variation of dynamic stress-strain curves,peak strain,compressive strength and elastic modulus with strain rate are analyzed,and the failure characteristics of rock under different strain rates are analyzed.2.The dynamic impact compression tests of natural water-bearing sandstone and natural saturated sandstone samples under 6 different temperatures of-20?,-15?,-10?,-5?,0?,and normal temperatures were carried out by SHPB test device.The variation of dynamic stress-strain curve,compressive strength,and failure modes with low temperature gradient is analyzed.The influence of water ice phase change on the dynamic mechanical properties of rock is studied,and the influence of water content on the compressive strength and deformation properties of rock is analyzed.3.The dynamic impact compression test of sandstone samples with different water content of natural water-bearing and natural saturated under 6 different loading rates of 0.3MPa,0.4MPa,0.5MPa,0.6MPa,0.7MPa and 0.8MPa was carried out by SHPB test device.The influence of water content on dynamic mechanical properties of rock is analyzed,and the failure mode of rock under different water content isanalyzed.4.The variation of incident energy,reflected energy,transmission energy and absorption energy under different freezing temperature,different loading rate and different water content is studied.The relationship between absorption energy and failure mode of rock is analyzed.The fitting relation between the absorption energy and the dynamic compressive strength is established.