矸石胶结充填体单轴压缩损伤破坏尺寸效应研究

Study on damage size effect of cemented gangue backfill body under uniaxial compression

为了研究尺寸对矸石胶结充填体损伤破坏的影响,制备尺寸为70.7,100,150,200和300 mm的立方体试件进行单轴压缩试验,监测试件在受载过程中的声发射及电阻率变化,并采用扫描电镜观测充填体的微观形貌,探讨不同尺寸矸石胶结充填体的损伤演化规律及破坏特征。结果表明:矸石胶结充填体的单轴抗压强度随尺寸的增大而减小,充填体的破坏形式随尺寸的增大从劈裂破坏逐渐转化为剪切破坏。尺寸较小的充填体在初始压密阶段比峰后破坏阶段呈现出更强的声发射活动特征,可以将声发射振铃的突变及电阻率的稳定阶段作为判定充填体破坏的前兆。根据试验结果建立矸石胶结充填体抗压强度的尺寸效应律计算公式及不同尺寸矸石胶结充填体的损伤模型及本构方程,可以为结构充填中充填体的设计提供参考。

In order to study the influence of size on damage and failure of cemented gangue backfill body(CGBB),cube specimens with sizes of 70.7,100,150,200 and 300 mm were prepared for uniaxial compression test.The acoustic emission(AE)and resistivity values of specimens during loading were monitored,and the micro morphology of the specimens was observed by scanning electron microscope.The damage evolution and failure mode of CGBB with different sizes were discussed.The results show that the uniaxial compressive strength of CGBB decreases with increasing the size,and the failure mode of CGBB gradually changes from splitting failure to shear failure with increasing the size.The smaller CGBB shows stronger AE activity in the initial compaction stage than in the post-peak failure stage.The sudden change of AE ringing and the stable stage of resistivity can be used as the precursor to judge the failure of CGBB.According to the test results,a calculation formula of size effect law of the compressive strength of CGBB and a damage constitutive model of CGBB with different sizes were established,which can provide reference for the design of backfill body in structural backfill.