Abstract: 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:① Under 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.② When 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.④ The 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.

Key words: composite filling structure,bearing,strength,stressstrain,damage and failure