裂隙砂岩失稳演化过程红外热效应及其破坏前兆规律研究

发布时间：2018-05-28 10:31

  本文选题：红外辐射温度 + 受载破坏　； 参考：《中国矿业大学》2017年硕士论文

【摘要】：红外辐射作为一种监测煤岩动力灾害的地球物理方法,其红外温度和红外热像具有反映煤岩受压破坏时间变化和空间演化特征的优势。为了进一步研究裂隙砂岩受载破坏的红外热效应及其前兆规律,本文搭建了裂隙砂岩红外热效应实验系统,测试了裂隙不同角度条件下的红外辐射。根据测定结果对裂隙砂岩单轴压缩下红外辐射温度不同指标进行分析,并对试样进行了不同裂隙角度条件下应力场、声发射动态分布和轴向位移场的变化模拟实验,通过用红外辐射等值线云图对试样失稳前关键时刻的温度场演化特征进行了对比分析,研究结果表明:(1)实验结果表明,试样受载破坏过程中红外辐射温度对破裂具有良好的响应,MIRT(最高红外辐射温度)异常信号表现为瞬间的突增、突降,AIRT(平均红外辐射温度)表现为整体的降转升或升转降。砂岩试样失稳破裂发生时,最高红外温度的增温幅度随着角度的增加呈现先升高后降低的趋势,变化幅度为0.14~1.36~0.11℃,其中转折点为60°或75°。(2)研究得到了砂岩试样加载过程中不同区域红外温度变化特征,位于预制裂隙两端区域呈现上升状态,升温幅度为0.08~0.17℃;位于预制裂隙中部两侧区域当预制裂隙角度为0°和45°时红外温度呈下降状态,降温幅度为0.03~0.09℃。当预制裂隙为75°时,预制裂隙中部上方区域温度曲线呈现降温状态,降温幅度达0.05℃;而中部下方区域的温度曲线呈现上升状态,降温幅度达0.08℃。(3)最高红外辐射温度曲线前兆规律主要表现为:降温前兆,红外温度降温幅度为0.05~0.2℃;升温前兆,红外温度升温幅度为0.1~0.3℃。平均红外辐射温度曲线前兆变化主要表现为:升温加速、降转升和升转降三种类型。其中对于最高红外辐射温度曲线前兆,试样预制裂隙角度为0°~60°时,载荷比基本都落在73~88%区间内,75°、90°时,主要集中在90%左右。(4)随着预制裂隙角度的增加,裂隙周围高应力区域面积逐渐增大;同时裂纹起裂强度越来越高,试样破坏强度也越来越大,试样的承载能力在不断增强。预制裂隙角度的增加使得声发射分布越来越分散。(5)试样表面红外辐射温度场变化与应力场的变化相对应;试样发生主破裂前红外辐射温度云图表现出的局部高温/低温区域可以很好的推测将要发生破坏的位置及主要破坏形式;同时试样表面红外温度场高温区域面积急剧下降的变化为试样的红外热像失稳前兆。
[Abstract]:Infrared radiation is a geophysical method for monitoring the dynamic disasters of coal and rock. Its infrared temperature and infrared thermal image have the advantages of reflecting the change of time and spatial evolution of coal and rock compression failure. In order to further study the infrared thermal effect of fractured sandstone under load and its precursor law, an experimental system of infrared thermal effect of fractured sandstone is set up, and the infrared radiation at different angles of fracture is measured. According to the measurement results, the different indexes of infrared radiation temperature under uniaxial compression of fractured sandstone are analyzed, and the simulation experiments of stress field, dynamic distribution of acoustic emission and axial displacement field under different fracture angles are carried out. The evolution characteristics of the temperature field at the critical moment before the instability of the sample are compared and analyzed by using the infrared radiation isoline cloud diagram. The results of the study show that: 1) the experimental results show that the temperature field evolves at the critical moment before the instability of the sample. The infrared radiation temperature has a good response to the rupture during the loading failure process. The abnormal signal of MIRT (maximum infrared radiation temperature) shows a sudden increase, and the sudden drop of AIRT (mean infrared radiation temperature) shows the whole down-turn or upturn. When the unstable fracture of sandstone specimen occurs, the temperature increasing range of the highest infrared temperature increases first and then decreases with the increase of angle, and the variation range is 0.14 ~ 1.36 ~ 0.11 鈩，

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