三软煤层沿空留巷顶板结构模型及合理支护研究

Research on Roof Structure Model and Reasonable Support of Gob-side Entry Retaining in Three-soft Coal Seam

为了揭示三软煤层沿空留巷围岩变形机理,探索适用于三软煤层巷道围岩控制的新技术,通过切顶沿空留巷物理相似模拟实验,研究了不切顶普通支护、切顶高强支护和切顶普通支护3种条件下顶板岩层断裂演化过程,构建了三软煤层切顶留巷顶板结构力学模型,给出了支护阻力计算方法,在韩城矿区象山煤矿进行了现场工业性试验验证。研究表明:切顶技术切断了顶板的应力传递,巷内采用高强支护,使顶板形成稳定的“短悬臂-砌体梁”结构。现场监测结果显示,不切顶普通支护的留巷顶底板平均移近量1000~1200 mm,两帮平均移近量600~700 mm;切顶高强单体支护的留巷顶底板平均移近量200~300 mm,两帮平均移近量200~300 mm;切顶组合式支架支护的留巷顶底板平均移近量50~100 mm,两帮平均移近量100~200 mm。组合式支架高强支护能够较好地控制三软煤层沿空切顶留巷围岩变形,可实现留巷二次复用无返修。

In order to reveal the deformation mechanism of surrounding rock in three-soft coal seam with gob-side entry retaining,and explore new technologies about strata control in three-soft coal seam.Through physical simulation experiment of gob-side entry retaining,the roof strata fracture evolution process under the three conditions of no roof cutting general support,roof cutting high-strength support,and roof cutting general support is simulated,the roof structure mechanical structure model of roof cutting gob-side entry retaining in the three-soft coal seam is established,and the calculation method of support resistance are given.On-site industrial tests were carried out and verified at Xiangshan coal mine in Hancheng mining area.The research shows that based on the overburden characteristics in three-soft coal seam,the roof-cut technology cuts off the stress transmission of the roof,and high-strength support is adopted in the roadway,therefore the roof can form"short cantilever beam-voussoir beam"structure.The on-site monitoring results show that under the condition of no roof cutting general support,the average approach distance of the roadway roof and floor is 1000-1200 mm,and the average approach distance of the two sides is 600-700 mm.Under the condition of roof cutting high-strength support,the average approach distance of the roadway roof and floor is 200-300 mm,and the average approach distance of the two sides is 200-300 mm.under the condition of roof cutting combined support,the average approach distance of the roadway roof and floor is 50-100 mm,and the average approach distance of the two sides is 100-200 mm.Therefore,the combined high-strength support can better control the serious deformation of the surrounding rock of the gob-side entry retaining in three-soft coal seam,and the remaining roadway can satisfy the secondary reuse with no repaired.