深部矸石充填体黏弹性效应及顶板时效变形特征

Viscoelastic effect of deep gangue backfill body and time-dependent deformation characteristics of roof in deep mining

深部充填开采矸石充填体的黏弹性特征对顶板长时变形具有重要影响.采用矸石充填体侧限压缩试验系统测试了矸石充填体的黏弹性,建立了矸石充填体分数阶蠕变模型和分数阶蠕变地基梁模型,给出了分数阶黏弹性地基梁的挠度表达式,结合工程案例分析了顶板时效变形特征,认为深部环境下矸石充填体具有显著黏弹性效应,而顶板会随充填体的蠕变不断产生变形,且其时效变形可采用矸石充填体分数阶黏弹性地基梁模型预测.结果表明:矸石充填体在分级加载下,总蠕变应变随蠕变时间和最大应力的增加而不断增长,应力达到20 MPa时,应变增幅为2.86%;识别了矸石充填体分数阶蠕变模型参数,参数识别精度R2均大于0.99;根据分数阶黏弹性地基梁挠度表达式计算得出顶板10 a蠕变量较1 a蠕变量在采场充填区中心位置增加2.73%;分数阶黏弹性地基梁顶板变形理论值与新巨龙1302N工作面直接顶下沉实测值相对误差为4.29%.

The viscoelastic characteristics of the gangue backfill body of deep filling mining have an important influence on the long-term deformation of the roof.The viscoelasticity of gangue backfill body was tested and analyzed using the confined compression test system of gangue backfill body.The fractional viscoelastic creep model of gangue backfill body and the mechanical model of fractional viscoelastic foundation beam were established.And the deflection expression of the fractional viscoelastic foundation beam was given.The time-dependent deformation characteristics of the roof were analyzed based on engineering cases.It is believed that the gangue filling body has a significant viscoelastic effect in the deep environment,and the roof will continue to deform under long-term aging with the creep of the gangue backfill body,and its aging deformation can be predicted by the gangue backfill body fractional viscoelastic foundation beam model.The results show that the total creep strain of the gangue is continuously increased with the increase of the creep time and the maximum stress under the staged loading.When the stress reaches 20 MPa,the strain increases by 2.86%.The parameters of the fractional creep model of the gangue backfilling body are identified,and the parameter identification accuracy R2 is all greater than 0.99.According to the deflection expression of the fractional viscoelastic foundation beam,the 10 a creep of the roof increases by 2.73%compared with the 1 a creep at the center of the stope filling area.The relative error between the theoretical roof deformation of the fractional viscoelastic foundation beam and the measured direct roof subsidence of Xinjulong 1302 N working face is 4.29%.