沿空留巷充填体蠕变特性数值模拟

Numerical Simulation on Creep Properties of Filling Body of Gob-side Entry Retaining

结合沿空留巷井下充填体的力学特性,得出充填体在井下基本呈现单轴压缩力学状态,进而选用FLAC3D数值模拟软件中的Cvisc模型对充填体蠕变特性进行分析,得出充填体在逐级加载条件下先后经历瞬时变形,稳定蠕变和加速蠕变3个阶段。其中,加速蠕变阶段充填体很快破坏,且加载强度基本在其本身强度的70%~72%;然后设计充填强度分别为3 MPa和5 MPa 2种方案对煤矿现场实际开采情况进行模拟,得出在不考虑充填体蠕变特性的情况下,3 MPa的强度就可以满足留巷要求;但引入时间效应后,充填强度为3 MPa的方案在1.6年后充填体承载失效,留巷失败,故最终确定了强度为5 MPa的充填方案。经过现场实践检验,充填体强度合理,留巷取得成功。

Combined with the mechanical characteristics of underground filling body of gob-side entry retaining, it is concluded that the filling body presents uniaxial compressive state in the underground, the creep characteristics of the filling body was analyzed by Cvisc model in software FLAC3 Dnumerical simulation, the backfill has experienced transient deformation, steady creep and accelerated creep three stages in the step by step loading process. Among them, the accelerated creep stage of backfill block damages rapidly and the loading strength is basically 70% to 72% of its own strength; then the designed filling strength of 3 MPa and 5 MPa two kinds of schemes are simulated in the coal mine site, it is concluded that the strength of 3 MPa can meet the requirement of gob-side entry retaining without considering the creep characteristic of the filling; however, after the introduction of the time effect, the filling strength of 3 MPa was lost in the filling body after 1.6 years, and the gob-side entry retaining is failure, finally, the filling scheme of 5 MPa is determined. After practice inspection in field, the filling strength is reasonable and the gob-side entry retaining is successful.