遇水冷却的高温大理岩力学与波动特性分析

Analysis of mechanical and wave properties of heat-treated marble by water cooling

岩石经历高温作用冷却后工程特性的变化情况,直接影响着地下深部空间及资源的开发与利用、核废料的存储以及突发性高温灾害后地下工程的稳定性评价。以大理岩为研究对象,对遇水冷却和自然冷却后的高温岩样进行单轴压缩试验和声波测试,分析和比较岩样在不同状态下峰值强度、弹性模量、衰减系数、纵波波速和主频的变化情况。结果表明:随着温度的不断升高,遇水冷却高温大理岩的峰值强度、弹性模量和纵波波速总体上均呈现减小趋势;低于400℃时,随着温度的升高,衰减系数逐渐增大,主频逐渐减小;但高于400℃时,随着温度的升高,衰减系数和主频并未完全呈现单调递增或递减趋势,出现了高温拐点;在经历相同高温作用后,遇水冷却大理岩的峰值强度、弹性模量和主频均低于自然冷却,而纵波波速、衰减系数均高于自然冷却。研究结果可以为遇水冷却的高温岩石工程性状的检测和稳定性的评价提供参考,对经历高温作用的岩石冷却方式的选择具有指导意义。

Mechanical properties of heat-treated rock after the cooling treatment directly influence the exploration and development of underground space and resources, storage of nuclear waste and stability evaluation of underground engineering after the high temperature disaster. Uniaxial compression and acoustic wave tests were conducted on heat-treated marble samples under the conditions of natural cooling and water cooling. Then, the variations of peak strength, elastic modulus, attenuation coefficient, longitudinal wave velocity and dominant frequency under different conditions were analyzed. A decrease trend is noted in peak strength, elastic modulus and longitudinal wave velocity of heat-treated marble by water cooling with the increase of treated temperature. When the temperature is lower than 400 ℃, the attenuation coefficient gradually increases and the dominant frequency gradually declines with the increase of temperature. When the temperature is higher than 400 ℃, the attenuation coefficient and dominant frequency do not completely exhibit monotonically increasing or decreasing trend, though there is a turning point. The peak strength, elastic modulus and dominant frequency of heat-treated marble samples after water cooling are lower than those after natural cooling, but the longitudinal wave velocity and attenuation coefficient are opposite. These results can provide references for the engineering health monitoring and stability evaluation of cooling methods on heat-treated rocks.