High Temperature Dynamic Mechanical Properties Of Sandstone Under Impact Loading

With the continuous mining of deep coal mine,geological environment encountered a variety of complex,deep rock mechanics behavior has become an important topic related to people's livelihood,also is one of the hot and key areas for future research of rock mechanics.In addition,in energy,geological engineering and other areas related to people's livelihood,such as deep buried nuclear waste,oil and natural gas underground mining and storage and geothermal resources development and utilization are related to the mechanical properties of rock under high temperature.Therefore,it is of great significance to study the dynamic mechanics of rock,especially the dynamic mechanical properties of rock at high temperature.In this paper,the dynamic compression test and dynamic splitting tensile test of deep coal mine sandstone under different temperatures were carried out by means of SHPB high temperature experimental device.The law of the variation of sandstone peak stress with temperature and the failure of sandstone are analyzed and the dynamic mechanical properties of sandstone were studied.At the same time,SEM and XRD experiments were carried out on sandstone samples with different temperatures,and the fracture morphology of the samples was observed.The main research contents and results are as follows:(1)Dynamic uniaxial compression tests on sandstone under three impact pressures of 0.3MPa,0.5MPa and 0.7MPa at room temperature(20?)?700? were carried out.The law of the variation of the peak stress of sandstone with temperature is analyzed.With the change of temperature,the peak stress of sandstone is roughly experienced three processes:gentle rising and falling.It can be seen from the broken pieces of the test pieces,each type of temperature,with the increase of the impact pressure,the degree of fragmentation of the sandstone is also increased,from the integrity of the short cylinder is broken into a block or powder.(2)Dynamic splitting tensile tests on sandstone under three impact pressures of 0.3MPa,0.5MPa and 0.7MPa at room temperature(20?)?700? were carried out.With the increase of temperature,the tensile strength of sandstone peak showed down process;with increasing the impact pressure of the sandstone specimen strain rate also in the increase in time for 50?300 s strain rate form a relatively stable platform.(3)SEM and XRD experiments on sandstone samples were carried out.The fracture morphology of the sample was observed and analyzed the composition of rock,the sandstone composition changes with temperature are analyzed,the sandstone rock in temperature should crack under the action of the expansion of the law.