Mechanical Properties Of Expansive Filling Material And Its Influence On Stratum Control In Stope

With the increasing demand of economic development for mineral resources,the mining depth of mine is gradually increasing.Under the background of strict requirements of various standards such as environmental protection,resource recovery and safety production,filling mining method has been widely used in metal mines because of its advantages of controlling surface subsidence and solid waste utilization.However,due to filling technology and slurry bleeding characteristics,the roof jointing effect of roadway filling is often not ideal.With the expansion of mining scale,the exposed area of stope roof increases,which brings hidden dangers to mine safety production.Based on the engineering background of Baixiangshan Iron Mine,this paper deeply analyses the influencing factors of non-roof-jointing in mine filling,and solves the problem of non-roof-jointing in mine filling by introducing foaming agent.Based on the study of filling materials,the mix ratio optimization and basic mechanical properties tests of expansive filling materials were carried out.Combined with damage mechanics theory and numerical analysis,the evolution law of mechanical damage of expansive filling materials and the influence of filling materials on stope formation control were systematically studied.The main work and research results are as follows:(1)Expansive filling material test and mix proportion optimization.Based on the tests of the basic properties of filling materials,slurry fluidity and expansibility,the two major factors affecting the non-roofing of Baixiangshan Iron Mine are analyzed.The results show that foaming agent has the advantages of improving slurry fluidity,expansibility,mass concentration and reducing bleeding rate,and lay a foundation for the subsequent study of the basic mechanical properties of expansive filling body.(2)Basic mechanical properties of expansive backfill.Based on the expansive filling after mixing,the basic mechanical properties of expansive filling under different loading conditions were tested.The evolution law of the mechanical properties of expansive filling with curing age,mass concentration,lime-sand ratio and foaming agent addition was revealed,and the basic physical and mechanical parameters of the filling were obtained.(3)Strength parameters and damage analysis of expansive filling.Based on the experimental study of mechanical properties of expansive filling body,the damage mechanics evolution law of expansive filling body is deeply analyzed.Combining with the theoretical basis of damage mechanics,the damage constitutive model of expansive filling body is constructed,and the damage parameters of filling body are analyzed.The damage evolution law of expansive filling body under different stress states is revealed.(4)Influences of expansive filling on stratum control in stope.Based on the analysis of the influencing factors of surface subsidence in mines,a mechanical model was established to reveal the influence of the height of non-roof filling on surface subsidence and roof stability.The numerical analysis of the influence of expansive filling on stope stability is carried out,and the evolution law of stope stability under the influence of different filling rate,roof joint rate and strength of roadway filling is revealed.