高温作用后玄武岩声发射特性及破裂机制研究

Study on Acoustic Emission Characteristics and Failure Mechanism of Basalt After High Temperature

为探究高温作用后玄武岩破裂特性与断裂机制,开展了25℃、200℃、400℃、600℃、800℃和1000℃条件下的玄武岩的加载试验和声发射测试,分析岩石破坏过程中声发射峰值频率和能量等声发射特征参数的演化规律,并对岩石破裂机制进行探讨。结果表明:高温作用对声发射信号特征影响显著,随着温度升高,峰值频率高频段占比增加,热损伤使裂纹发育时间缩短、扩展速度加快、扩展规模变小。热处理对岩石爆裂性具有促进作用,声发射定位点由分散态逐渐趋于聚集态,随着温度的升高,声发射定位点汇聚成核时期提前,声发射绝对能量在应力峰值前出现波动。高温作用改变了玄武岩的破裂模式,随着温度的升高,玄武岩的破裂机制由剪切破坏转变为拉伸破坏。

To explore the failure characteristics and mechanisms of basalt after high temperature,the loading experiments and acoustic emission tests were conducted on basalt samples temperatures at 25℃,200℃,400℃,600℃,800℃and 1000℃.The evolution laws of acoustic emission(AE)characteristics such as peak frequency and energy during the rock fracture process were analyzed,and the mechanism of the rock fracture was also explored.The results show that the high temperature has a significant influence on the AE signal characteristics.With the increase of temperature,the proportion of high peak frequency increased.Thermal damage shorten the development time of the microcracks,while accelerating the expansion speed but reducing the expansion scale.The heat treatment of the rock has an additive effect on the burstiness.The AE localization points gradually converge from the dispersed state to the aggregated state.With the increase of temperature,the period of convergent nucleation of the AE localization sites is advanced,and the absolute AE energy before the peak stress is fluctuated.The high temperature has modified the failure pattern of basalt.With the increase of temperature,the failure mechanism of basalt transformed from shear failure to tensile failure.