急倾斜采场上盘顶板预应力锚杆条网带支护间距设计方法研究

Study on supporting spacing design method of prestressed bolt bar mesh belt of hanging roof in steeply inclined stope

针对某矿急倾斜采场上盘顶板局部冒落,提出采用2~3排预应力锚杆加条网构成的锚杆条网带沿倾向间隔一定距离支护该顶板。应用材料力学建立该顶板的锚杆条网带支护力学模型,分析其冒落机理,并基于三弯矩方程推导锚杆条网带支护间距设计公式。应用FLAC3D正交数值模拟各种赋存条件下上盘顶板锚杆条网带支护的最佳间距,系统分析矿体埋深、倾角、厚度及顶板岩梁高度对锚杆条网带支护间距的影响,并多元线性回归修正了该支护间距设计公式,最后将修正的公式应用于该矿深部留矿法采场上盘顶板锚杆条网带支护间距设计。研究结果表明:急倾斜采场上盘顶板中央弯矩最大,是冒落控制的关键部位;锚杆条网带支护该顶板具有减跨效应,可以有效减小其中央的集中拉应力,经济有效地避免其冒落。

In view of the local fall of hanging roof at steeply inclined stope in a mine,the bolt bar mesh belt composed of 2—3 rows of prestressed anchor rods and strip belt was proposed to support the stope roof along a certain inclined distance.In the paper,the mechanical model of bolt bar mesh belt support was established by material mechanics in the stope roof,and the mechanism of the roof fall was analyzed,moreover,the design formula of supporting spacing of bolt bar mesh belt was deduced based on the theory of three bending moment equation.Furthermore,the orthogonal numerical simulation of FLAC3D was used to simulate the optimal spacing of the roof bolt bar mesh belt support under various occurrence conditions,and the influences of ore body buried depth,dip angle,thickness,and roof rock beam height on supporting spacing of bolt bar mesh belt were systematically analyzed,meanwhile the design formula of support spacing was modified by multiple linear regression.Finally,the modified formula was applied to the design of the roof bolt bar mesh belt support in deep shrinkage stope.The results indicated that the bending moment in the center of the stope roof was the largest,which is the key part of the caving control.The stope roof supported by bolt bar mesh belt has the effect of reducing span,which can effectively reduce the concentrated tensile stress in the center of the stope roof,and the roof fall can be avoided economically and effectively.