坚硬顶板沿空留巷巷旁“让-抗”支护机理

Supporting mechanism of “yielding-supporting” beside roadway maintained along the goaf under hard rocks

坚硬顶板条件下沿空留巷,工作面顶板悬顶距大,悬顶时间长,巷旁支护体将承受较大的压力,支护体易发生变形和破坏。通过建立坚硬顶板沿空留巷巷旁支护力学模型及对顶板不同运动阶段支护体内应力分布和围岩变形数值模拟,结果表明:在顶板岩层运动早期支护体应具有较大的可缩量,在保持支护体本身不遭受严重损坏的前提下,允许顶板产生一定下沉,以释放掉一定的顶板压力;在顶板岩层运动后期支护体应具有较高的支护阻力,抵抗坚硬顶板部分重量并进行断顶。提出了不等强充填体(上软下硬材料组合而成)支护方式,在坚硬顶板条件下采用该支护方式能较好地实现沿空留巷开采技术。

When using gob-side entry retaining on the condition of hard roof, roadside support deforms and destroys easily because the length of hanging roof is large, the roof hangs long, and the stress ex- erted on roadside support is large. Mechanical model for gob-side entry on the condition of hard roof was built, and stress distribution of roadside support and deformation of surrounding rocks during dif- ferent movement stages were simulated. Results show that in the early movement stage, in order to re- lease some roof stress, roadside support should have larger yieldable capacity which allows roof to have certain subsidence under the premise that the support is not destroyed severely. In the later movement stage, roadside support should have greater strength to resist the weight of hard roof and cut roof. Based on this mechanism, unequal strength support body which is combined by soft material on the top and hard material in the bottom is put forward, and the field practice demonstrates that gob-side entry re- taining technology on the condition of hard roof can be better achieved by using unequal strength sup- port body.