双向荷载作用下被充填矿柱的力学特性

Mechanical behavior of backfilled pillar under biaxial loading

在矿柱周边进行充填形成的矿柱-充填体协同承载结构是充填开采的关键,也是维持地下采场稳定性的重要支撑结构。通过双向加载试验,研究了被充填矿柱在不同侧向应力、充填率和充填体力学特性条件下的承载能力和破坏模式,分析了矿柱-充填体复合结构的承载特性及相互作用过程。结果表明,随着侧向应力的增加,矿柱与充填体之间的界面摩擦力(充填率<100%)和有效充填体强度(充填率=100%)比矿柱强度增加更加显著,故前两者是双向加载条件下矿柱-充填体支撑结构承载力增加的主要原因。此外,由于矿柱和充填体两者之间显著的刚度差异,双轴加载试验中充填体的有效强度会低于其单轴抗压强度,而侧向应力的增加,不仅会提高界面摩擦力和充填体的有效强度,也会影响矿柱和充填体的破坏模式。该研究对分析矿柱-充填体相互作用和共同承载机制具有参考和借鉴价值。

Backfilling the pillar to form a pillar-backfill collaborative bearing structure is the key to cut and fill method.The pillar-backfill bearing system is also an important support structure to maintain the stability of the underground stope.This paper analyzed the load-bearing capacities and failure modes of the backfilled pillars through biaxial compression tests,and the combined effects of lateral stress,fill ratio,and backfill mechanical properties were investigated.The results showed that the mobilized interface friction force between the pillar and backfill(fill ratio<100%)and effective backfill strength(fill ratio=100%)increased faster than pillar strength with lateral stress gain,which were the main reason for the increase in the load capacity of the backfilled pillar under biaxial loading.In addition,due to the significant stiffness difference between the pillar and backfill,the effective strength of the backfill in the biaxial loading test was lower than uniaxial compressive strength.The increase of lateral stress could not only improve the interface friction and the effective strength of backfill,but also affect the failure modes of the pillar and backfill.The experimental results will have reference value for studying the interaction of pillar-backfill structure.