Experimental study on the mechanical properties of rocks at high temperature

The mechanical properties of marble,limestone,and sandstone as well as the stress-strain curve,the varying characteristics of the peak strength,the peak strain and elastic modulus were studied by using the MTS810 Rock Mechanics Servo-controlled Testing System under the action of temperatures ranging from room temperature to 800℃.Results show that (1) the peak strength and elastic modulus of marble fluctuate at the temperature from normal to 400℃ ;and they decrease gradually over 400 ℃.(2) With the rise of the temperature,the peak strength and elastic modulus of limestone show downward trend from normal temperature to 200℃ ;have little change from 200 ℃ to 600 ℃;and decrease sharply over 600 ℃.(3) The peak strength of sandstone shows a downward trend while a little change for elastic modulus at normal temperature to 200 ℃;and from 200 ℃ to 600 ℃,the peak strength of sandstone increases while a little change for elastic modulus;the peak strength and elastic modulus decrease rapidly at the temperature over 600℃.(4) The peak strain of limestone shows little change at normal temperature to 600℃,however,the peak strain increases rapidly over 600℃ ;and for marble and sandstone,the peak strain decreases with the rise of the temperature from normal temperature to 200℃,the peak strain increases rapidly over 200℃.The result can provide valuable references for the rock engineering design at high temperature.