Study On Strength Characteristics And Ratio Design Of High Stage Whole Tailing Cemented Backfill

LiLou iron ore is the larger domestic underground metal mines and uses of 100m high stage cemented filling method.The ore was separated into rooms and pillars.At present,due to the high stage and high sublevel of Li Lou iron ore,the volume of single mined-out area was up to 10?16×104 m3.During the two-step mining process,the stope convergence,the ratio design and strength characteristics,and the stress distribution of high stage cemented backfill,which seriously restricted the safety and economy of the stope.In this paper,the strength characteristics and filling ratio of the cemented backfill were studied based on the multiple methods,which include engineering geological investigation,laboratory mechanics experiment,theoretical analysis,numerical simulation,in-situ strength detection and electron microscopy.The main research works were as follows:(1)Based on the engineering geological investigation and laboratory mechanics experiment,the dominant structure planes and the mechanical parameters of the ore rock were obtained.The mechanical parameters of the rock are obtained by calculating the mechanical parameters of the rock.After the reduction calculation,the mechanical parameters of the related rock mass were used for subsequent numerical calculation and analysis.During the two-step mining of pillars,field survey found that the collapse of the filling body was serious and the distribution of the damaged parts was uneven,which highlighted the effect of the slurry ratio,strength property,spatial distribution of strength and two-step mining time on the second-security mining.(2)Through tailings material performance test of Lilou mine,positive correlation mathematical expressions between the strength of cemented backfill body and the curing age are established.The energy matching coefficient is introduced to show the energy density relationship between the backfill body deformation and the ore excavation at the open stope with the subsequent filling method,which obtain relationships between the coefficient and elastic modulus of ore,the vertical stress,the curing strength of cemented backfill and the curing time of cemented backfill body.Based on that,the excavated time in the second step is quantitatively analyzed.(3)By analyzing the mechanical contact state between cemented filler body and surrounding rock,the three-dimensional mechanical model of cemented backfill under lateral pressure was deduced and the stress distribution law of filling body was revealed.The two-step numerical simulation by FLAC was used to analyze the stress field,displacement field and plastic failure zone of cemented backfill with different matching parameters.Based on the arrangement of mine filling engineering,three-dimensional mechanics model and two-step numerical simulation of mining,the ratio parameter design of high-stage filling stope was put forward.(4)In the Lilou iron mine,the difference strength between the in situ samples and the surface test blocks was analyzed based on the macro-micro coupling.The in situ strength increment of cemented backfill was "hump"morphological distribution.Furthermore,The mechanism of self-weight pressure and drainage arrangement on the curing strength of high stage cemented backfill was revealed from the micro-pore structure development characteristics.At the ratio optimization area of high stage filling stope,to achieve safe mining at the same time,the filling costs was reduced and economic efficiency was improved.