高温下石灰岩和砂岩膨胀特性的试验研究

Experimental research on swelling properties of limestone and sandstone at high temperature

利用自行研制的高温岩石膨胀特性试验装置,对石灰岩和砂岩试件300～700℃高温过程中的膨胀特性进行试验研究。试验结果表明,升温过程中,石灰岩和砂岩的膨胀应力随温度的增加而增大,且砂岩膨胀速率比石灰岩大,刚到700℃时砂岩膨胀应力是石灰岩的2.45倍。升温过程中膨胀应力与温度曲线的拟合函数为2次抛物线,相关系数达0.94以上。恒温过程中,随时间延长2种岩石的膨胀应力缓慢增加,最后逐渐趋于稳定的数值。600℃高温后2种岩石膨胀均达到极限,但具体表现不同,700℃恒温结束时砂岩稳态膨胀应力是石灰岩的3.14倍。岩石热膨胀应力变化与其岩性、内部矿物分解、孔隙率变化、声速变化等有显著关系。

The swelling properties of limestone and sandstone at 300 ℃ to 700 ℃ were investigated by the experiment system used to measure the swelling properties of rocks at high temperature and designed by ourselves.The experimental results show that the swelling stresses of limestone and sandstone increase with temperature increasing during raising temperature;and the swelling velocity of sandstone is more quickly than the limestone.The swelling stress of sandstone is 2.45 times as that of limestone when just reaching to 700 ℃.The fitted functions of curves about swelling stress and temperature are second-degree parabolaes during raising temperature;and the related coefficients are all above 0.94.The swelling stresses of two kinds of rocks increase slowly during constant temperature with time prolonging and tended to steady values at last.Two kinds of rocks＇ swelling stresses reach to the limit values at 600 ℃;but the specific processes are different.The swelling stress of sandstone is 3.14 times as that of limestone when constant temperature process finished at 700 ℃.The swelling stress of rock is obviously related to lithological characters,mineral resolving,porosity and sound velocity.