充填膏体蠕变宏观硬化试验研究

为探索煤矿充填膏体的长期强度特征,采用水泥、粉煤灰、煤矸石等材料按照1∶4∶6配比制成充填膏体试件,对其进行了单轴压缩与蠕变试验。基于试验结果,分析了充填膏体试件的物理特性、蠕变瞬时变形模量等参数变化规律。研究表明:充填膏体致密性差、可压缩性强,在缓慢加载过程中试件趋于均匀、致密;蠕变试验过程中,在破坏前的各级应力水平上,随着应力水平提高和变形增加,充填膏体试件的瞬时变形模量增大,增长率为1.77×105%;同时,每级应力水平下弹性应变阶段的应变率随应力水平提高而逐渐减小;充填膏体蠕变强度大于单轴抗压强度,平均蠕变系数为1.09,充填膏体在蠕变过程中强度发生了宏观硬化。

Experimental study on creep macroscopic hardening of filling paste

To study the long-term strength characteristics of filling paste in coal mine, the uniaxial compression experiments and creep experiments of filling paste specimens have been performed. The weight ratio of cement, fly ash to coal gangue has been 1∶4∶6 in those specimens. The physical cha-racteristics, instantaneous deformation modulus and other features of filling paste specimens have been analyzed based on the experimental results. The results have shown that filling paste has poor density and strong compressibility, and the internal structure of filling paste becomes homogeneous and dense during the slow loading process. Under each stress level of creep experiments, the instantaneous defor-mation modulus of filling paste increases gradually with the enhancements of stress and deformation before the failure of specimens, and the growth rate is 1.77×105%. At the same time, the strain rates in elastic strain stage decrease gradually. The results have also indicated that the creep strength is higher than uniaxial compressive strength, the average creep coefficient is 1.09, and that the macroscopic strength hardening has occurred in creep experiment.