深部硬岩截割特性及可截割性改善方法

Fragmentation characteristics of deep hard rock and improvement for rock cuttability

深部硬岩的截割特性受到岩石特性、截割参数、应力环境等众多因素影响。利用TRW−3000型岩石真三轴电液伺服诱变(扰动)试验系统研究了受限应力条件、截齿加载方式、岩石力学特性、人为诱导缺陷等对硬岩截割特性的影响。研究发现:在单轴受限应力下,随受限应力增大岩石截割由易变难再变易,高单轴受限应力反倒有利于截齿破岩,但当单轴受限应力过高时,截齿破岩扰动易引发岩爆;动静组合破岩时,截齿预静载越大破岩能力越强;随着岩石脆性指数的增大,岩石可截割性先降低后升高;诱导加卸荷损伤、临空面切槽、临空面钻孔等人为诱导缺陷可提高硬岩的可截割性。同时,获得了深部硬岩可截割性改善方法,提出了深部硬岩矿体非爆机械化开采模式。采矿试验证明,开挖诱导巷道致裂矿体形成松动区后利用掘进机破岩和在矿柱底部开挖预切槽后利用高频破碎锤破岩,可将非爆机械化采矿效率从32.6 t/h分别提高到107.7 t/h和158.2 t/h。

Cuttability of hard rock is influenced by many factors, such as rock properties, cutting parameters, and stress conditions. Using TRW-300 true triaxial electro-hydraulic servo system, the influences of confining stress conditions, loading mode of conical pick and rock properties(brittleness and artificially induced defect) on rock breakage were investigated. Under uniaxial confining stress condition, the rock cutting difficulty initially increases and then decreases with increases in uniaxial confining stress, and the high uniaxial confining stress instead improves the rock cuttability. However, the ultra-high uniaxial confining stress may induce rock burst. The high preload applied on pick can achieve the high cutability. Rock cuttability presents decrease followed by increase with increases in rock brittleness. In addition, excavation-induced fractures, pre-slit and pre-borehole in rock mass can improve hard rock cuttability. Moreover, the improvement measures of rock cuttability were achieved, and the non-explosive mechanized mining mode in deep hard rock was proposed. The mining tests prove that the efficiencies of non-explosive mechanized mining improves from 32.6 t/h to 107.7 t/h and 158.2 t/h, respectively,with cuttability improvement measures of the excavation of induced entryway to pre-fracture orebody cut by roadheader and the excavation of pre-slit in pillar broken by high-frequency crushing hammer.