高温热损伤后花岗岩声发射及特征能量研究

Study on Acoustic Emission and Characteristic Energy of Granite After High-Temperature Thermal Damage

为了揭示高温加热对花岗岩弱化机制的影响,利用岩石单轴伺服压力机与声发射测试系统,研究了4个温度梯度下热处理后的花岗岩在单轴压缩变形过程中特征点的声发射信号和能量变化规律。结果表明:随着温度升高,花岗岩刚性减弱、塑性增强,峰值应力呈加速下降趋势,宏观破坏时变形量增大;声发射信号变化与应力-应变曲线相关性较好,闭合点和起裂点声发射计数率占比受温度影响较小,损伤点声发射活动受温度影响较大;花岗岩闭合点、起裂点和损伤点的总输入能和弹性能与加热温度呈正相关,峰值点耗散能的变化反映出500℃和600℃间存在一个温度临界值,使得岩石内部出现严重损伤。研究结果可为我国干热岩地热资源开发与利用提供理论参考。

In order to reveal the influence of high-temperature heating on the weakening mechanism of granite,the acoustic emission signal and energy variation law of characteristic points during uniaxial compression deformation of granite after heating treatment under 4temperature gradients were studied by using rock uniaxial servo press and acoustic emission test system.The results are concluded as follows.Firstly,as the temperature increases,the rigidity of granite weakens,the plasticity increases,the peak stress shows an accelerated downward trend,and the deformation amount increases during macroscopic failure.Secondly,the changes in acoustic emission signals correlate well with stress-strain curves.The proportion of acoustic emission counting rate at the closure point and the initiation point is less affected by temperature,while the acoustic emission activity at the damage point is more affected by temperature.Thirdly,the total input energy and elastic energy at the closure point,initiation point,and damage point of granite are positively correlated with the heating temperature.The change in peak dissipation energy reflects a temperature critical value between 500℃ and 600℃,causing serious damage inside the rock.The research results can provide a theoretical reference for the development and utilization of dry hot rock geothermal resources in China.