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为了揭示微波能量对煤体孔裂隙结构的影响作用,设计了循环微波辐射实验,采用红外热成像、超声波探测、核磁共振和高精度X-CT扫描技术探讨了不同微波辐射时间下,煤体孔裂隙结构演化特性。结果表明:微波对煤体有开孔、疏孔和塌孔效应,其中开孔效应和疏孔效应占主导,微波辐射增大了煤体总孔体积和孔间连通性,使束缚流体孔隙率和自由流体孔隙率分别增大了30.3%和167.9%。微波辐射后,煤体内不同组分具有微波吸收异质性,煤体升温不均产生热应力,热应力撕裂原生裂隙并催生出新裂隙,从而导致NMR渗透率增大,超声波波速减小。煤样内部微裂隙增多并于辐射1.5min后转变为中、大裂隙,从而在煤体中形成裂隙网.
In order to reveal the effect of microwave energy on the pore structure of coal pores, a cyclic microwave irradiation experiment was designed. The infrared emission, infrared detection, nuclear magnetic resonance and high-precision X-CT scanning were used to investigate the effect of microwave energy on the pore structure of coal. Crack structure evolution characteristics. The results show that the microwave has the effect of opening, sparse holes and collapsible holes on the coal, in which the open hole effect and the sparse hole effect dominate, and the microwave radiation increases the total pore volume and inter-pore connectivity of the coal so that the bound fluid porosity And free fluid porosity increased by 30.3% and 167.9% respectively. After microwave radiation, different components in the coal have microwave absorption heterogeneity, and the thermal stress of the coal body heats up unevenly to generate thermal stress, which leads to the increase of the permeability of NMR and the reduction of the ultrasonic wave speed. The micro-cracks in the coal samples increased and transformed into medium and large cracks after 1.5 min of radiation, thus forming a fracture network in the coal.