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不同黏结剂掺量条件下型煤试样三轴压缩试验研究

Study on triaxial compression tests on briquette coal specimens with different binder contents

  • 摘要: 为制备与原煤力学性质更为相似的型煤样品,以普通硅酸盐水泥为黏结剂,开展不同黏结剂掺量条件下型煤三轴压缩试验,对比分析2种煤样应力-应变、破裂形态、力学参数等差异性变化,揭示黏结剂掺量对型煤宏观力学性能的影响。试验结果表明:随着围压的增加,不同黏结剂掺量条件下型煤试样压密阶段和弹性阶段变化与原煤呈现相似的变化规律,而屈服阶段与峰后阶段变化与原煤差异较大;随着黏结剂掺量的增加,型煤轴向应变与黏聚力也随之增大,而型煤弹性模量与内摩擦角却不断减小。研究结果说明,黏结剂掺量增加可改善煤内部大量煤粉颗粒间的固结能力,一定程度上提高了型煤的力学强度与刚性特征,使得型煤宏观破裂形态由典型的塑性破坏向剪切破坏转变,呈现出理想的弹-塑性材料变形特征。不同煤样特征值空间向量的欧式距离计算结果表明,型煤IV的力学特征与原煤更为接近。

     

    Abstract: To produce briquette coal with mechanical properties more similar to raw coal,a series of triaxial compression experiments were conducted using different contents of ordinary Portland cement as a binder. The stress-strain relationship,failure mode,and mechanical parameters of various specimens were compared to reveal the influence of binder content on macroscopic mechanical properties. The experimental results indicate that the changes in the compaction stage and elastic stage of different briquette coal specimens are similar to those of raw coal as the confining pressure increases,but there is a significant difference in the yield stage and post-peak stage. As the binder content increases,the axial strain and cohesion of the briquette coal increase,while the elastic modulus and internal friction angle decrease. These results show that the consolidation ability between massive pulverized coal particles can be improved with an increase in binder content,leading to an enhancement in the mechanical strength and rigidity characteristics of the briquette coal to a certain extent. Consequently,the failure mode of briquette coal specimens changes from typical plastic failure to shear failure,presenting ideal elastic-plastic material deformation characteristics. The calculation results of Euclidean distances of eigenvalue vector space reveal that the mechanical characteristics of briquette coal IV are closer to those of raw coal.

     

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