Research On Mechanical Properties And Reinforcement Of Backfill With Weak Interlayer

Soft interlayer of backfill is a weak structure which affects the integrity of backfill and weakens the quality of backfill.In the actual production of mines,the existence of weak interlayer may lead to the strength of backfill can not meet the strength requirements of filling mining method,and lead to the collapse or even collapse of backfill,affecting the ore recovery index and threatening the safety of underground production.Aiming at the influence of weak interlayer and quality of backfill on mechanical properties of backfill,the concept of reinforcement of backfill is put forward,aiming at strengthening the strength of backfill and improving the stability of backfill.In order to reveal the mechanical properties and failure mechanism of backfill with weak interlayer and reinforced backfill,this paper takes backfill with weak interlayer and reinforced backfill as the research object,and studies the influence of weak interlayer and reinforced backfill on the mechanical properties and failure mechanism of backfill by means of theoretical analysis,laboratory simulation test and data analysis.Firstly,through the theoretical analysis of the mechanical mechanism of the weak interlayer and the backfill with the weak interlayer,the causes of the formation of the weak interlayer,the failure modes,the ultimate load under extrusion conditions and the coupling mechanism of the weak interlayer weakening the mechanical properties of the backfill are revealed.On the basis of theory,the effect of thickness,strength and inclination of weak interlayer on the mechanical properties of backfill under uniaxial compression test was studied,and the strength reduction rate was used to characterize the mechanical properties of backfill.Secondly,theoretical analysis and uniaxial compression test are carried out to reveal the coupling mechanism between reinforcement and backfill and the failure mode of reinforced backfill.The theoretical study shows that the reinforcement mechanism of reinforced backfill is the coupling effect of reinforcement and backfill,which improves the cohesion of backfill without changing the friction angle of backfill.The experimental results show that the mechanical properties and failure modes of backfill are changed by reinforcement of backfill.The peak strength of failure is increased by 1.07-1.35 times and the modulus of elasticity is increased by 1.08-4.42 times.Finally,based on the backdrop of upward filling mining method in a mine,field application of filling reinforcement is carried out,and the effect of Filling Reinforcement on improving the strength and stability of backfill is verified by field application effect.