龙滩矿沿空留巷顶板突变式变形规律与复合支护切顶技术

Sudden deformation characteristic and cutting-roof support technology for double-used roadways in Longtan Mine

针对沿空留巷顶板卸压效果难以保障、围岩控制效果差等问题,以龙滩矿沿空留巷为工程背景,通过对沿空留巷顶板变形规律进行全过程监测,揭示了沿空留巷采动影响期间的顶板突变式变形规律,获取了顶板发生突变式变形的关键时机。结果表明:在切顶爆破卸压条件下,测站处沿空留巷顶板最大下沉量虽然在工程允许范围内,但都出现了2次明显的突变现象,主要是由超前支承压力的影响和留巷区域顶板悬顶结构失稳导致。据此,形成了分阶段复合支护切顶技术,以对抗2次顶板变形突变,第1阶段采用增效锚固切顶长锚索,第2阶段采用切顶支柱与半封闭式小型框式切顶支架。工程监测结果表明,复合支护切顶卸压效果良好,留巷围岩可较好的保持稳定。

Double-used roadways suffer high abutment pressures,leading to severe roadway deformation which may not be mitigated using traditional stress relief technologies.A case study was performed at a double-used roadway of Longtan Mine.A cutting-off technology was used to deal with the strong roof of the double-used roadway for stress relief.The deformation of the roadway was monitored during the entire service period.It shows that the roadway exhibited a sudden deformation pattern.Two times of sudden deformation occurred and the maximum roof deformation was acceptable.The critical timing of the sudden deformations was captured.It is found that the sudden deformation was due to the influence of the abutment pressure and the instability of the suspended roof structure in the roof area of the roadway.A two-stage cutting-off strategy was proposed to deal with the two sudden deformations.The first stage was using long cable bolts with extra bond strength to support the roadway roof.The second stage was using a combination of standing pillars and semi-closed small frame brackets for supplemental support.Field monitoring data suggests that this support strategy successfully controlled the deformation of the double-used roadway.