Effect Of Two Cooling Methods On Dynamic Mechanical Properties Of High Temperature Sandstone

Coal mine roadways and tunnels will encounter gas explosion and fire accidents.The rock walls of roadways and tunnels will experience water spraying and water cooling after a long period of high temperature heating,and some roadways and tunnels after fire will still be affected by dynamic loads such as explosion and earthquake in the later period.Therefore,studying the physical properties and dynamic mechanical properties of rock after high temperature and high temperature water cooling will have important engineering significance for safe production and disaster prevention.In this paper,the sandstone of Gubei Coal Mine of Huainan Mining Group in Anhui Province is taken as the research object.The sandstone specimens after high temperature heating are cooled by natural cooling and water cooling.The basic physical parameters of sandstone specimens were measured.The impact compression test and dynamic splitting tensile test of sandstone specimens after two cooling methods were carried out by using the split Hopkinson pressure bar(SHPB)test device.1.The basic physical parameters of sandstone specimens under natural conditions and after two cooling methods were measured.The effects of two cooling methods on the volume,mass,density and longitudinal wave velocity of sandstone specimens were studied.Studies have shown that the volumetric expansion rate,mass loss rate,density reduction rate and longitudinal wave velocity reduction rate of sandstone specimens are positively correlated with the increase of temperature in a quadratic function,and water cooling has a significant impact on the change rate of physical parameters of sandstone specimens.2.The sandstone specimens subjected to different temperatures(20℃,100℃,200℃,300℃,400℃,500℃,600℃,700℃,800℃,900℃,1000℃)and two cooling methods were subjected to impact compression tests under 0.3MPa loading pressure.The effects of two cooling methods on the dynamic stress-strain curve,dynamic compressive strength,dynamic elastic modulus,strain rate,dynamic strain and impact failure morphology of sandstone were compared and analyzed.The research shows that the deterioration degree of parameter indexes of dynamic compression mechanical properties of water-cooled high-temperature sandstone is greater than that of natural-cooled high-temperature sandstone.3.Dynamic splitting tensile tests of sandstone specimens under different temperatures(20℃、100℃、200℃、300℃、400℃、500℃、600℃、700℃、800℃、900℃,1000℃)and two cooling methods were carried out by SHPB equipment under 0.3 MPa loading pressure.The dynamic tensile stress-strain curve,dynamic tensile strength,dynamic tensile modulus and impact failure morphology of high temperature sandstone specimens after two cooling methods were compared and analyzed.The research shows that the deterioration degree of parameter indexes of dynamic tensile mechanical properties of water-cooled high-temperature sandstone is greater than that of natural-cooled high-temperature sandstone.Graph[42]Table[6]Parameter[41]...