树脂锚固材料的高温锚固特性及其受热解影响的CT分析

Anchoring properties and CT analysis affected by the pyrolysis of the resin anchoring material at high temperature

树脂锚固材料广泛应用于岩土工程加固,但其高温下具有的热解特性直接影响材料的锚固性能。通过高温拉拔、抗压实验与CT分析相结合的方法,研究高温下树脂锚固材料的锚固力学特性及其受热解细观结构变化的影响特征。研究结果表明：（1）高温拉拔实验中,20℃-250℃时,随着温度升高锚固力增大,250℃时达到峰值69.5 k N,较常温增大45.1%,这是由于树脂锚固材料内部充分固化的结果;250℃-350℃范围锚固力下降为47.2k N,较峰值减少32.1%;但在350℃-400℃范围,模拟管中的锚固材料发生爆裂与剧烈炭化,平均锚固力下降为15.2 k N,且500℃-600℃时完全失去锚固力。（2）高温抗压实验中,200℃时抗压强度达峰值65.8 MPa,较常温增加31.3%;350℃-400℃时强度较常温衰减95.2%,在600℃时强度衰减达99.3%。（3）CT扫描分析,350℃-500℃锚固材料平均灰度衰减22.6%,孔隙团大小增幅达199.6%。可见,350℃后树脂锚固材料快速热解炭化、内部孔隙剧增是造成其锚固力衰减的根本原因。

Resin anchor material has been widely used in underground engineering supporting. The pyrolysis characteristics of resin anchor material at high temperature directly affect its anchoring mechanical properties. The mechanical properties and variation characteristics of mesoscopic structures were analyzed using the pull-out tests and compression experiments and micro-CT scans undertaken at high temperatures. The high-temperature pull-out test results show that the anchoring force increases as the temperature increases from 20 ℃ to 250 ℃ and reaches the peak of 69.5 k N at 250 ℃ with an increase of 45.1% compared with the normal situation,which is due to the full solidification of the internal material. At the temperature of 250 ℃ to 350 ℃,the anchoring force is reduced to 47.2 k N,with a decrease of 29.2% compared with the peak value. At temperature of 350 ℃ to 400 ℃,the anchoring material in the simulated tube bursts and chars severely,with the average anchor force dropping to 15.2 k N. The anchoring force was completely lost from 500 ℃ to 600 ℃. In the high temperature compression experiments,the strength reaches the peak of 65.8 MPa at 200 ℃,with an increase of 31.3% compared with normal situation. At 350 ℃–400 ℃,the intensity reduces 95.2% compared with the normal value and at 600 ℃,the strength reduces 99.3%. CT analyses show that the average grey scale of the anchoring material reduces 22.6% at 350 ℃–500 ℃. The size of pore group increases 199.6%. Hence,the rapid pyrolysis and charring of resin anchoring material after 350℃ and the dramatic increase of internal pores are the fundamental causes of anchoring force attenuation.