冻融循环下纤维改性充填体的力学特性研究

Study on Mechanical Properties of Fiber-modified Backfill under Freeze-thaw Cycle

为了有效降低矿山地下采场岩爆灾害、合理控制采场围岩变形,一般采用尾砂充填地下采空区,传统的尾砂强度很难在复杂的地下空间中发挥作用,尤其是高寒高海拔矿区的冻融循环环境,有必要确保冻融环境下的充填体具有良好的力学性能。为研究冻融循环对纤维改性充填体力学行为的影响,首先将不同质量百分比(0、0.2%、0.4%、0.6%、0.8%、1.0%)的纤维与充填料浆混合进行混合,然后对纤维—充填体混合物进行0、5、10、15次冻融循环,并讨论了纤维改性充填体混合物的坍落度、单轴抗压强度、劈裂抗拉强度随纤维掺量和冻融循环次数的变化趋势。结果表明:循环冻融显著降低了纤维改性充填体混合物的力学性能,纤维的适量掺入对充填体力学性能改善起到了主要作用,纤维掺量为0~0.6%时可以有效提高充填体的强度,纤维掺量超过0.6%时会劣化充填体的力学性能。此外,纤维的掺入极易与充填体内的水分融合而起到固水作用,从而抑制其流动性。

In order to effectively reduce rock burst disaster in underground stope and reasonably control the deformation of surrounding rock in stope,tailings are generally used to fill underground goaf.The traditional strength of tailings is difficult to play a role in complex underground space,especially in the freeze-thaw cycle environment of high-cold and high-altitude mining areas.Therefore,it is necessary to ensure that the backfill in freeze-thaw environment has good mechanical properties.In order to study the effect of freeze-thaw cycle on the mechanical behavior of the fiber-modified backfill,firstly,the fiber with the per-centage of non-mass(0,0.2%,0.4%,0.6%,0.8%,1.0%)was mixed with the filling slurry for mixing,and then the fiber-backfill mixture was mixed for 0,5,10,15 freeze-thaw cycles.The variation trends of slump,uniaxial compressive strength and splitting tensile strength of fiber-modified backfill mixture with fiber content and number of freeze-thaw cycles were also dis-cussed.The results show that the cyclic freeze-thaw can significantly reduce the mechanical properties of the fiber modified backfill mixture,and the appropriate incorporation of fiber plays a major role in improving the mechanical properties of the backfill.When the fiber content is 0~0.6%,the strength of the backfill can be effectively improved,while when the fiber con-tent is more than 0.6%,the physical properties of the backfill will be degraded.In addition,the incorporation of fiber is easy to fuse with the water in the filling body and play a role in fixing water,thus inhibiting its fluidity.