分级加载下矸石胶结充填材料蠕变特性研究

Creep Properties of Coal Gangue Cemented Backfill Material Under Step Loading

矸石胶结充填材料用于煤炭资源的充填开采时,其长期工作性能关系到采空区安全与稳定。为探讨无侧限充填体长期稳定性,制备不同骨料级配和不同水胶比的试样进行单轴压缩分级加载蠕变试验,并分析了长期稳定强度、蠕变硬化系数等参数。结果表明:基于A.N.Talbol骨料级配理论制备的矸石胶结充填材料可满足流动性能要求,其28d单轴抗压强度随水胶比增加而降低,n为0.8时最高,为6.73MPa;除n为0.9外,其他n值的充填体蠕变破坏强度大于28d单轴抗压强度,长期稳定强度在n为0.6时最高,为8.13MPa,n为0.9时最低,为4.47MPa,且随水胶比增加而降低,从8.82MPa降至5.83MPa,水胶比0.642是其急速转缓慢下降的临界值;在n为0.6、水胶比0.542时,蠕变硬化系数最大,分别为1.31和1.38,且随n值和水胶比增加而降低。

When the coal gangue cemented backfill material is used for the coal mining,its long-term performance affects the safety and stability of the goaf.In order to explore the long-term stability of these unconfined backfill bodies,the samples with different aggregate grading and water-binder ratio were prepared to carry out the step-loading uniaxial compression creep experiments.Then,the long-term stability strength,creep hardening factor and other factors were analyzed.The results showed that:the coal gangue cemented backfill material prepared based on the A.N.Talbol aggregate grading theory met the flowability requirement,its uniaxial compressive strength in 28 d increased with the decrease of water-binder ratio,and reached the highest value of 6.73 MPa when n was 0.8.The creep damage strength of other groups was larger than the uniaxial compression strength of 28 d except n=0.9.The long-term stability strength reached the highest value of 8.13 MPa when n was 0.6,while reached the lowest value of 4.47 MPa when n was 0.9.Furthermore,the long-term stability strength decreased from 8.82 MPa to 5.82 MPa with the increase of water-binder ratio,and 0.624 of water-binder ratio was the critical value between the rapid and slow declining.The creep hardening factor reached the highest value of 1.31 and 1.38 when n was 0.6 and water-binder ratio was 0.524,respectively,and decreased with the increase of n value and water-binder ratio.