Mechanical Property Of Interbeded Filling Body And Its Effect On Stability Of The Retaining Wall

The stability of backfill-wall is one of the key factors restricting safe and efficient mining.Full height non-cementing filling is adopted in high stopes.Even if pillars are not mined,the stability of backfill-wall is difficult to guarantee.The backfill-wall is stable but filling cost is high with full height non-cementing filling.In order to solve this contradiction,interbedded filling can be used(in this paper,interbedded filling specifically refers to the cementing and non-cementing interlayer),but the filling effect is not ideal when applied to engineering practice.The reason is that the physical characteristics of interbedded filling and its influence backfill-wall stability are still unclear,scholars at home and abroad have relatively few studies on interbedded filling,and there is no specific theory to solve practical engineering problems.Therefore,it is urgent to study the mechanical properties of interbedded filling and its influence on the stability of backfill-wall,reveal the rule of stress change in interbedded filling,construct the mechanical model of cementing layer in interbedded filling,investigate the influence of interbedded filling on stability of backfill-wall,propose a new method for structural parameter-designing of backfill-wall,and achieve the purpose of enriching filling theory and solving the problem of the engineering practice.The main contents as follows:(1)The type and relation of stress for interbeded filling are analyzed,and the"floor" effect of the backfill cemented in interbeded is found.It is that the rule of stress change in interbeded can be revealed during filling process,a relation between horizontal stress and vertical stress in backfill-bottom&non-cemented can be obtained.(2)The variation rule of horizontal stress for intermediate cementing layer with thickness and filling height can be obtained,it is from mechanical models which constructed from three layers interbeded and intermediate cementing layer,also the variation rule of cementation thickness with ultimate tensile strength and upper load.Comparing the methods,it is concluded that the interbeded has a function in controlling the pressure.(3)The impact of filling slurry for backfill-wall in initial filling is studied,a dynamic mechanical model for interbeded to the wall can be constructed,the influence rules on dynamic pressure for slurry height and groove bottom gradient can be obtained,and the dynamic mechanical model for slurry can be proved by field test.(4)The variation rule for pressure of interbeded to wall during in process is revealed,a static mechanical model for interbeded to bulkheads is constructed,the rules of static pressure for interbeded to wall with distance and upper load can be obtained,and the model can be proved in situ.Compared with the rules of pressure from filling-wall in different processes,the pressure from interbeded is reduced a lot.(5)A new theoretical method for structure’s parameters-designing of wall is proposed.The mechanical model for wall thickness and wall reinforcement are established based on elastic mechanical model,the relations for thickness with filling-height at one time and tensile strength of wall concrete can be obtained,also the quantity of reinforcement with filling load and thickness of filling-wall.