热处理温度对受载花岗岩能量演化影响试验研究

Experimental study on the influences of thermal treatment temperature on the energy evolution of loaded granite

为了有效评估花岗岩在高温环境下的工作性能,对饱水和干燥两种状态下的岩石试样,设计了5个温度梯度的热处理试验,通过波速测试试验初步评估岩石的热损伤情况,并在此基础上,针对干燥热处理试样开展了轴向加载试验。结果表明,随温度增加花岗岩波速减小,并在500~600℃间波速出现明显下降,热处理温度越高岩石裂隙越发育。且相同热处理温度下饱和花岗岩波速大于干燥花岗岩;从常温~500℃处理的干燥花岗岩强度以恒定速率下降,而在600℃花岗岩强度显著减小,表明花岗岩在500~600℃间存在热应力损伤临界点;不同温度下花岗岩试件在峰前阶段表现为能量积聚,在峰后阶段表现为能量释放,温度越增加应变能释放梯度越缓慢,体现了高温对岩石延性的增强特性。

To evaluate the service behavior of the granite under high temperature,a 5 groups'test with temperature gradients were designed,and the thermal damage condition of the rock samples were confirmed employing the elastic wave velocity measurement.Based on these,axial loading tests were carried out on the dry heat-treated rock samples.The results show that:(1)With the increase of temperature,the wave velocity of granite reduces,with sharp decreases under 500~600℃.The higher the heat treatment temperature,the more developed the rock fracture;(2)Under the same heat treatment temperature,the wave velocity of saturated granite is higher than that of dry granite;(3)Treated from room temperature to 500℃,the strength of dry granite decreases at a constant rate,with a significant decrease at 600℃,indicating that there was a critical point of thermal stress damage between 500℃and 600℃;(4)Under different temperatures,granite samples show energy accumulation in the pre peak stage and energy release in the post peak stage:The slower the gradient of strain energy release with the increase of temperature,the stronger the plasticity.