煤火区不同温度后砂岩动态特性试验研究

Dynamic characteristics of sandstone after heating at different temperatures in the coal fire area:an experimental study

为揭示煤火燃烧区砂岩的动态力学行为规律及特性,本文以宁夏汝籍沟煤田火区砂岩为研究对象,采用分离式霍普金森压杆试验装置对其进行多次冲击试验。本文选择25、200、400、600、800和1000℃6个温度等级,冲击气压0.58、0.60和0.62 MPa 3个气压等级为试验参数,研究不同冲击气压下不同高温后砂岩试件的动态力学参数及动态破坏形态的影响规律。研究表明:在同一冲击气压作用下,砂岩应变率随温度的升高而增大,而峰值应力随温度的升高而降低;当砂岩处于同一热处理温度时,砂岩的应变率随冲击气压的增大而增大。在冲击气压为0.6 MPa时,常温和热处理温度为200、400、600℃砂岩试件的破坏裂纹均出现在侧表面;热处理温度为800和1000℃砂岩试件的撞击端呈粉碎性破坏。煤火区砂岩在不同温度下的热损伤能够改变其动态力学性能。

To reveal the law of dynamic mechanical behavior and the characteristics of sandstone in a coal fire combustion area,taking the sandstone in the Rujigou coal fire area of Ningxia as the research object,we used a split Hopkinson pressure bar test device to perform several impact tests.Six temperature grades of 25,200,400,600,800,and 1000℃ and three impact pressure grades of 0.58,0.60,and 0.62 MPa were selected as test parameters.The dynamic mechanical parameters and dynamic failure modes of sandstone specimens were studied after heating at different high temperatures under different impact pressures.The results showed that under the same impact pressure,the strain rate of sandstone increased,and the peak stress decreased with increasing temperature.When the sandstone was at the same heat treatment temperature,the strain rate of the sandstone increased with increasing impact pressure.When the impact pressure was 0.6 MPa,the failure cracks of sandstone specimens at room temperature and the heat treatment temperatures of 200,400,and 600℃ appeared on the side surface.The impact ends of the sandstone specimens with heat treatment temperatures of 800 and 1000℃ were crushed.Thermal damage to sandstone in the coal fire area at different temperatures could change its dynamic mechanical properties.