| Due to the depletion of shallow resources,the exploitation and utilization of deep resources has become an inevitable trend of future development.However,with the increase of mining depth,the ground temperature of deep rock mass increases sharply,and high temperature cycle exists in dynamic disturbance processes such as underground rock mass blasting and mechanical mining.After the high temperature environment,the mechanical properties of rock are changed,and the strength and deformation of underground rock mass are particularly prominent,which puts forward higher requirements for the support and safety of underground rock mass structure.Therefore,it is of great theoretical practical significance to explore the change rules of dynamic mechanical properties of rocks after high temperature cycling.This paper takes the roadway sandstone of Gubei Coal Mine of Huainan Mining Group of Anhui Province as the research object.The basis physical indexes of sandstone,such as mass,volume,density and longitudinal wave velocity,were tested at room temperature and after high temperature cycling,and the variation rules of basic physical indexes of sandstone after normal temperature and different high temperature cycling were analyzed.The RMT-150B rock mechanics test system was used to conduct static uniaxial compression test on the sandstone at room temperature,and the SHPB test device was used to conduct experimental study on the dynamic characteristics of multi-strain rate of sandstone specimens after different high temperature cycles.The main research contents are as follows:1.The basic physical indexes such as mass,volume,density and compressional wave velocity of sandstone specimens were studied after cycling at room temperature(25℃)and different high temperatures(200℃,400 ℃,600℃,800℃,1000℃)for 2,4,6,8 and 10 times.2.The RMT-150B rock mechanics testing system was used to conduct the static uniaxial compression tests on sandstone specimens subjected to normal temperature.The static stress-strain curve was obtained,and the variation characteristics of the stress-strain curve were analyzed in detail.3.Using the SHPB test units to room temperature(25℃)and experience different high temperature(200 ℃,400℃,600℃,800℃,1000℃)circulation 10 times after the sandstone specimen of the same loading rate of shock compression test(impact pressure p=0.3MPa),analyzes the dynamic compressive strength and dynamic strain and dynamic power parameters such as elastic modulus changing with the temperature effect.4.The whole process from deformation to failure of sandstone in SHPB test after cycling at room temperature(25 ℃)and different high temperatures(200 ℃,400 ℃,600℃,800℃,1000℃)was observed and analyzed with high-speed video,and its deformation and failure characteristics were analyzed.5.The impact compression tests of sandstone specimens cycled for 10 times at 400℃ under 8 loading rates were studied.The dynamic stress-strain curve variation characteristics of sandstone and the strain rate effect of sandstone specimens subjected to impact compression tests at different loading rates were analyzed.The dynamic parameters of sandstone,such as dynamic compressive strength,dynamic strain and dynamic elastic modulus,vary with the incident energy from the perspective of energy dissipation.6.The SHPB test fragments of sandstone after high temperature cycling were screened to obtain the average particle size and fractal dimension of the fragmentation under the condition of multi-strain rate,and the impact failure characteristics of sandstone were quantitatively analyzed.Figure[47]table[22]reference[59]... |
