Physical and dynamic mechanical behaviors of marble after heat treatment in quasi-vacuum and air-filled environments

准真空和空气环境下大理岩高温后物理及动力学特性

The dynamic mechanical properties of rock specimens after thermal treatment in the air-filled environment(AE:i.e.,at the free surface)have been extensively investigated,yet they are rarely estimated in the quasi-vacuum environment(VE:i.e.,far from free surface),which is of special importance in engineering practice.Several precise laboratory tests(i.e.,split Hopkinson pressure bar test)on marble samples in both AE and VE were performed to investigate physical and dynamic mechanical behaviors of marble after heat treatment(25℃ to 900℃)in AE and VE.The tests results demonstrate that related properties of marble could be divided into three different stages by corresponding critical temperatures of 300℃ and 600℃,at which heat damage factors are 0.29(0.30)and 0.88(0.92)in VE(AE),respectively.The thermal damage developes more fully in AE than in VE.The thermal environment plays an important role,especially in Stage 3.Specifically,a conspicuous difference(greater than 20%)between AE and VE occurs in corresponding dynamic strength and the anti-deformation capacities of tested marble specimen.The influence of heat damage of rock is very important and valuable in engineering practice,particularly when the temperature is very high(greater than 600℃).

空气环境下热处理后的岩石动态力学性能已被广泛研究,但目前对于准真空环境下高温对岩石的动态力学性能的影响却鲜有涉及,而这在工程实践中具有重大意义。对准真空和空气环境下热损伤(25℃到900℃)后的大理岩试样进行了相关检测及动态冲击试验(基于霍普金森压杆),对其物理参数及动态力学特性劣化机制进行了探究。试验结果表明,大理岩相关性质的劣化过程可分为三个阶段,临界温度分别为300℃及600℃,其对应的热损伤因子分别为0.29和0.88(准真空环境),0.30和0.92(空气环境)。可见,热处理过程中试样所处环境至关重要,空气环境下高温对大理岩造成的损伤更为明显,特别是在第三阶段。此外,两种环境下热处理后的大理岩试样在动态抗压强度及抗变形能力上都有很大不同(大于20%)。热损伤对岩石的影响在工程实践中非常重要意义与价值,特别是对于超高温环境(大于600℃)。