Study on Damage Energy Consumption Characteristics and Mechanical Behaviour of Mixed Aggregates Cemented Backfill Before Peak Stress

Abstract

Mixing coarse aggregates into cemented paste backfill can significantly affect its mechanical properties. Many mixed aggregates cemented backfill samples were carried out uniaxial compression tests to see how the coarse aggregate replacement rate affects its uniaxial compressive strength, and analyze the influence on the damage energy consumption characteristics of the backfill before peak stress based on damage mechanics theory. Then taking Jinchuan No. 2 Mine as an example, study the stability and mechanical behaviour of the backfill in the stope by means of numerical simulation. The results show as following: The uniaxial compressive strength of the backfill at different curing ages has a quadratic function curve relationship with an increasing coarse aggregates replacement rate. This indicates that there exists an optimal replacement rate of 60%. When the content of coarse aggregate exceeds the optimal value, the strain value of the backfill sample corresponding to the peak stress damage value decreases, which means that the more the content of coarse aggregate, the more the backfill sample is prone to brittle failure. The peak stress specific energy increases first and then decreases with increasing coarse aggregate replacement rate, shows a similar change with its uniaxial compressive strength, so the backfill with the higher uniaxial compressive strength have stronger energy storage mechanism. The numerical simulation results show that the backfill with the optimal coarse aggregate replacement rate can effectively relieve the stress concentration of the rock mass in the stope, however the filling body has obvious tensile damage due to the mining activities.