水泥尾砂充填体劈裂拉伸破坏的能量耗散特征

Destroy energy dissipation characteristics of cement-tailings backfill under splitting tensile condition

应用INSTRON刚性伺服试验机对不同灰砂比的充填体进行了劈拉试验,测得荷载-位移和应力-应变全曲线.结合测得的力学参数计算出相关能量耗散特征参数,分析了不同情况下破坏过程的能量耗散变化规律,并通过数据统计回归建立了各种能量耗散指标与其影响因素的函数关系.实验结果显示:充填体只需吸收极少能量即可满足拉伸破坏所需,拉伸破坏是影响充填体断裂性质的主导因素.为防止充填体处于受拉环境,在矿房回采时应采用边孔控制爆破和不耦合装药,优化爆轰波破岩途径,减少欠挖超挖,保证矿柱形态规整,使充填体处于非拉区域以改善其受力状况;同时在矿房充填时应对需布设工程或应力集中区域等关键部位适当加大灰砂比,以增强充填体吸收破坏能量的能力.

A series of splitting tensile tests were conducted by using an INSTRON testing system to investigate the effect of cement-tailings ratio on the properties of backfill. Based on experimental data, the evolvement laws of energy dissipation under different conditions were presented and some correlative formulae were proposed to describe the relationship between energy dissipation and in- fluencing factors, tt was found that tensile failure acted as the dominant factor for eventual failure of backfill and energy was dissipated less for tensile failure. Several optimized measures were suggested to reduce, even eliminate, the tensile state in backfill. Control blasting of periphery-holes and decoupling charging should be used to reduce under-excavation and over-excavation by optimizing the propagation of detonation wave. Crucial parts, where projects are disposed and stress concentrates, should be reinforced by special backfill with large cement-tailings ratio to improve the energy absorption capacity of the structure.