一维动静组合加载下充填体动力学性质试验研究

充填采矿法二步回采时,充填体矿柱不可避免地受到爆破振动的扰动。开展对其动力学特性的研究对实现二步矿柱安全高效回采具有重要的理论意义和工程价值。以尾砂胶结充填体为研究对象,选取不同轴压水平,开展不同应变率的SHPB动载单轴冲击试验,对一维动静组合加载下充填体的动静组合加载强度、变形特性、能量传递规律和破坏模式进行了分析。研究表明:①在应变率近似相同的情况下,充填体试样的动态强度会随着轴向载荷的施加而呈现先增大后减小的趋势,而在轴向载荷相同的情况下,充填体试样的动态强度随着应变率的增加而增加,两者显现了较强的相关性;②充填体试样冲击试验应力-应变曲线主要分为3个阶段:弹性阶段、屈服阶段和破坏阶段,没有明显体现出压密阶段,并且充填体试样在低应变率条件下并不敏感;③吸收能随入射能的增加,整体呈现增加趋势,但是增加幅度略有降低,单位体积吸收能随应变率的增加而逐渐增加,透射能的增量随入射能的增加逐渐减小;④常规SHPB情况下,充填体试样的破坏模式为拉伸破坏,组合加载条件下,充填体试样的破坏模式主要为压剪破坏。

Experimental Study of Dynamic Characteristics of Backfill under One-dimensional Coupled Static and Dynamic Loads

The backfill pillar is inevitably disturbed by the blasting vibration in two-step mining. Investigation on its dynamic characteristics has important theoretical significance and engineering value for realizing safe and efficient mining of two-step pillars. Taking tailings cemented backfill as research object， SHPB dynamic uniaxial impact tests with different strain rates were carried out at different axial compression levels. The dynamic and static combined loading strength， deformation characteristics， energy transfer law and failure mode of backfill under one-dimensional dynamic and static combined loading were analyzed. The results showed that: （1） The dynamic strength of the backfill will first increase and then decrease with the the axial load in the case of approximately the same strain rate. The dynamic strength of the backfill sample will increase with the increase of the strain rate in the case of the same axial load， and both of them have a strong correlation relationship. （2） The stress-strain curve of the backfill is mainly divided into three stages: the elastic stage， the yield stage and the failure stage， and the compaction stage is not clearly appeared in impact tests. What’s more， the backfill is not sensitive under low strain rate. （3） The absorption energy slightly increases with the increase of incident energy. The absorption energy per unit volume increases with the increase of strain rate， and the increment of transmission energy decreases with the increase of incident energy. （4） In the case of conventional SHPB tests， the failure mode of the backfill is tensile failure. The failure mode of the backfill is mainly compression-shear failure in the case of the coupled static and dynamic loads.