高温作用后黄砂岩的力学特性研究

RESEARCH ON MECHANICAL PROPERTIES OF YELLOW SANDSTONE AFTER HIGH TEMPERATURE

对经25~1 000℃作用后的黄砂岩进行常规三轴压缩试验,研究黄砂岩的表观形态和力学特性。研究结果表明:经不同温度作用后,黄砂岩呈不同的颜色,总体上随着温度的升高,颜色会加深。经600℃作用后,受温度影响岩体体积膨胀逐渐明显,体积变化率增大。温度从25℃升到1 000℃的过程中,黄砂岩的密度和弹性模量随温度的上升逐渐降低。围压作用下的黄砂岩,在600℃之前,峰值强度随温度的升高明显呈二次非线性升高,弹性模量下降较小;在600~1 000℃时,峰值强度随温度变化呈二次非线性下降趋势,弹性模量也呈下降趋势,且温度越高,降幅越大。黄砂岩经不同温度作用后,在围压由5 MPa增大到15 MPa时,其最大振铃计数率及累计振铃计数率均发生改变。

The conventional triaxial compression tests of the yellow sandstone after temperature of 25 ℃ to 1 000 ℃was carried.The apparent state and mechanical properties of yellow sandstone at the different temperatures were measured.The test results showed that the yellow sandstone presented different colors at different temperatures,in general,the higher the temperature,the darker the colour.When the temperature was above 600 ℃,the volume expansion was obvious and the volume change rate increased.When the temperature increased from 25 ℃ to1 000 ℃,the density and elastic modulus of yellow sandstone decreased with the increase of temperature.When the temperature was below 600 ℃,the peak strength of the yellow sandstone specimens’ rose by quadratic nonlinearity with temperature increasing,and the elastic modulus decreased less.The peak strength decreased by quadratic nonlinearity from 600 ℃ to 1 000 ℃.The elastic modulus decreased,and the higher the temperature,the greater the decreasing amplitude.When the confining pressure increased from 5 MPa to 15 MPa,the maximum ring-down count rates and the cumulative ring-down count rates changed at different temperatures.