摘要
为研究高温对岩石力学特性和内部结构的影响,对高温处理后的花岗岩进行单轴压缩和声发射测试。研究结果表明:高温对花岗岩力学特性影响显著,由于高温导致脱水和热膨胀,加热到200℃使花岗岩的强度升高了15%;此后,峰值强度随着处理温度升高而大幅降低,这归因于矿物晶粒的过度膨胀和相变引起的裂纹发育;此外,花岗岩逐渐由脆性破坏转为延性破坏,对应的临界温度在400℃和600℃之间;不同于低温下的情况,加热到600℃及以上的花岗岩在加载的初始阶段就有明显的声发射现象,这与高温诱发的热裂纹在外载荷作用下迅速扩展有关。考虑到初始热损伤,提出了一个修正的损伤变量,其变化特征较好地揭示了热处理后花岗岩在单轴压缩下的损伤演化过程。
In order to investigate the effects of elevated temperature on the mechanical behaviors and internal structure of rocks,uniaxial compressive experiments and acoustic emission tests were performed on the granite after thermal treatment.The results demonstrated that elevated temperature significantly influenced the mechanical behaviors of granite.Due to the dehydration and the thermal expansion caused by elevated temperature,heating to 200℃increased the peak strength of granite by 15%.Then,the peak strength was greatly reduced with temperature increase,which was attributed to the development of cracks induced by the excessive thermal expansion and the phase transition of mineral grains.Moreover,the failure mode of granite gradually transformed from brittle to ductile,and the corresponding critical temperature was between 400℃and 600℃.Different from the situations at lower temperature,the acoustic emission of the granites heated up to 600℃ or higher was distinct at the initial stage of loading.This was related to the rapid propagation of thermal cracks induced by elevated temperature under the external load.Considering the initial thermal damage,a modified damage variable was proposed,and its variation characteristics could well reveal the damage process of specimens experienced thermal treatment under uniaxial compression.
作者
马兵
陈虹宇
MA Bing;CHEN Hongyu(College of Resources and Environmental Science,Chongqing University,Chongqing 400044,China;China State Construction Bridge Corp.,Ltd,Chongqing 402260,China)
出处
《矿业研究与开发》
CAS
北大核心
2020年第1期22-27,共6页
Mining Research and Development
基金
国家自然科学基金资助项目（51611140122）
关键词
花岗岩
高温
声发射
损伤
Granite
Elevated temperature
Acoustic emission
Damage
作者简介
马兵(1993—),男,湖北荆州人,硕士研究生,主要从事岩石力学及矿山安全方面的研究,E-mail:20162002013t@cqu.edu.cn。
