崩矿步距对回采进路围岩稳定性的影响

Influence of Caving Distances on the Stability of Surrounding Rock of Mining Drift

为揭示无底柱分段崩落法开采时,崩矿步距对回采进路围岩稳定性的影响,以辽宁某铁矿为例,在该矿现有的采场结构参数下,设定5种不同的崩矿步距,采用数值模拟的方法,研究了崩矿后的进路围岩位移和塑性区分布。不同崩矿步距下崩落矿石后,进路围岩均处于压应力状态,且随距端壁面距离的增加,最大主应力与最小主应力均呈现出先增大后减小的态势,最大主应力在距端壁面2 m处达到最大值,而最小主应力在距端壁面4~5 m的范围内达到最大值。增大崩矿步距有利于改善进路的围岩应力状态。以不同崩矿步距崩落矿石后,在进路的两侧帮及拱肩处形成了“蝴蝶状”的位移区域,在进路顶部形成了“下沉”位移区域。增大崩矿步距,围岩位移量均略有增长,但改善了位移的分布特征,缩小了位移范围。崩落矿体后,围岩内部的塑性区以剪切塑性区为主,张拉塑性区分布范围很小。崩矿步距增大后,剪切塑性区体积及其增幅远比张拉塑性区的大,围岩易发生剪切破坏。

In order to reveal the influence of caving distances on the stability of surrounding rock of mining drift during mining with non-pillar sublevel caving method,an iron mine in Liaoning Province was taken as the research example.Under the existing mining structure parameters of this mine,five different caving distances were set,and numerical simulation methods were used to study the displacement and plastic zone distribution of the surrounding rock after the caving.After the ore caving at different caving distances,the surrounding rock of the drift was in a state of compressive stress,and as the distance from the end wall increases,the maximum principal stresses and minimum principal stresses showed a trend of first increasing and then decreasing.The maximum principal stress reached its maximum value at a distance of 2 meters from the end wall,while the minimum principal stress reaches its maximum value within a range of 4-5 meters from the end wall.Increasing the caving distances was beneficial for improving the stress state of the surrounding rock in the drift.After caving the ore at different caving distances,a“butterfly shaped”displacement area was formed on both sides and arch shoulders of the drift,and a“sinking”displacement area was formed at the top of the drift.Increasing the caving distance resulted in a slight increase in the displacement of surrounding rock,but improved the distribution characteristics of displacement and narrowed the range of displacement.After caving the ore body,the plastic zone inside the surrounding rock was mainly as shear plastic zone,and the distribution range of tensile plastic zone was very small.After increasing the caving distance,the volume of the shear plastic zone and its increase are much larger than those of the tensile plastic zone,and the surrounding rock was prone to shear failure.