复合充填结构体承载破坏演化特征

Bearing Failure Evolution Characteristics of Composite Filling Structure

针对力学性质存在差异的材料组合而成的复合充填结构体在承载过程中内部应力分布不均的现象,开展了由不同强弱介质组合而成的复合充填结构体的单轴压缩试验。结合声发射特征分析,研究了复合充填结构体的承载特征、损伤演化和破坏特征。研究表明:①单轴压缩状态下复合体内部应力分布不均,强介质内部应力大于弱介质内部应力,整体荷载主要由强介质承担;②当复合体中强介质强度一定时,复合体整体强度与弱介质强度呈正相关;③当弱介质强度小于等于3.21 MPa时,复合体应力—应变曲线出现两个弹性阶段,且第一弹性阶段的斜率大于第二弹性阶段,随着弱介质强度增加,第一弹性阶段增长、第二弹性阶段缩短,当弱介质强度大于3.21 MPa时,第二弹性阶段消失;④声发射信号演化特征表明:两个弹性阶段的拐点处弱介质出现大量损伤破坏,弱介质先于强介质破坏,当弱介质强度大于3.21 MPa时,损伤主要发生在压密和屈服后阶段,弱介质与强介质同时破坏。研究成果可为地下采场复杂应力场控制措施研究提供基础。

Aiming at the phenomenon that the internal stress distribution of composite filling structure,composed of materials with different mechanical properties,is uneven in the bearing process,uniaxial compression test of composite filling structure composed of different strong and weak media were carried out.Combined with the analysis of acoustic emission characteristics,the bearing characteristics,damage evolution and failure characteristics of the composite filling structure are studied.The results show that:①Under uniaxial compression,the internal stress distribution of the composite is uneven,the internal stress of the strong media is greater than that of the weak media,and the strong media bearing the overall load.②When the strength of strong media is constant,the overall strength of the composite sample is positively correlated with the strength of weak media.③When the strength of the weak media is lower than a certain critical value,the stress-strain curve of the composite has two elastic stages,and the slope of the first elastic stage is greater than that of the second elastic stage.With the increase of the strength of the weak media,the first elastic stage increases and the second elastic stage decreases.When the strength of the weak media exceeds the critical value,the second elastic stage disappears.④The evolution characteristics of acoustic emission signal show that at the deflection point of the two elastic stages,a large number of damage occurs in the weak media,and the damage of the weak media precedes that of the strong media.When the strength of the weak media is higher than the critical value,the damage mainly occurs in the compaction and post yield stages,and the weak media and the strong media are destroyed at the same time.The research results can provide a basis for the study of the control measures of complex stress field in underground stope.