粉煤灰膏体充填置换条带煤柱强度研究

Study on the Strength of Fly Ash Paste Filling Replacing Strip Pillar

针对过去"三下"开采遗留的大量保护煤柱,因地制宜地提出了粉煤灰充填体整体置换回采条带煤柱的方法。依据采场上方"裂断拱"时空演化规律并结合裂断拱内岩石自重计算充填条带初期强度应大于0.49MPa,后期强度应大于4.42MPa。为了获得充填体的最优配比,设计了正交试验,分析了石灰含量、石膏含量和水泥含量对不同龄期强度的影响程度。结果表明:水泥含量是影响膏体前期1,3,7d抗压强度的主要因素;石灰含量是影响膏体后期28d抗压强度的主要因素。综合多种因素考虑,最终选择粉煤灰∶生石灰∶石膏∶水泥为68%∶15%∶12%∶5%的配比为最优配比。

Aimed at lots of residual safety pillars in coal mining under water body,building and railway,the method of using fly ash filling body to replace strip pillars was put forward.According to the spatio-temporal evolution of the"fracture arch"above the stope and the self-weight of rock in the fracture arch,the initial strength of the filling strip should be greater than 0.49 MPa,and the later strength should be greater than 4.42 MPa.In order to obtain the optimum proportion of filling body,orthogonal tests were designed to analyze the influence degree of lime content,gypsum content and cement content on the strength at different ages.The results showed that the cement content were the main factor affecting the initial compressive strength of paste in 1 d,3 dand 7 d,and the lime content were the main factor affecting the late compressive strength of paste in 28 d.Combining various factors,the optimum proportion of fly ash,quicklime,gypsum,and cement was selected as 68%∶15%∶12%∶5%.