Study On Macro-meso Mechanical Properties Of Gangue Cemented Filling Body

With the rapid development of industrialization in China,green mining has become an inevitable choice for the development of mining enterprises.As an important part of green mining system,gangue cemented filling mining has been paid more and more attention by scholars for its advantages of effectively controlling the displacement of overlying strata and surface subsidence in goaf.Therefore,in this paper,the gangue cemented filling body as the main research object,through the experimental research,theoretical analysis and numerical simulation method of gangue cemented filling body macro meso-mechanical properties research,the optimal proportion of gangue cemented filling body optimization,analysis of different sizes of gangue cemented filling body macro damage mechanical properties,research of gangue cemented filling body mesolevel mechanical properties and structural damage characteristics and crack evolution.The main research results are as follows:(1)Through orthogonal experiment,the best mix ratio test of gangue cemented filling was carried out.The particle size distribution,slurry concentration,sand-ash ratio,fly ash content,slump,bleeding rate and uniaxial compressive strength of gangue cemented filling slurry were studied.The results showed that the best mix ratio of gangue cemented filling was particle size distribution K = 0.2,slurry concentration L = 76%,sand-ash ratio S = 4 and fly ash content F = 25.(2)Through the uniaxial compression test on different sizes of gangue cemented filling,it is found that the compressive strength of the gangue cemented filling body with the size increases first and then decreases the trend,according to the experimental results to establish a gangue cemented filling body size effect degree formula to provide a certain reference for its size effect research.(3)Through acoustic emission test,the uniaxial compression process of gangue cemented filling body is redefined as four stages;The changing law of ringing count and energy in different stages of gangue cemented filling samples with different sizes was analyzed.the research indicated that the sudden change of acoustic emission ringing could be used as the precursor to determine the failure of gangue cemented filling.the size mainly had great influence on the formation and expansion of internal cracks of gangue cemented filling,thus leading to the difference of acoustic emission events.(4)Based on the strain equivalent theory and the introduction of the compaction coefficient,the damage constitutive equation representing the uniaxial compression process of coal gangue cemented backfill is established,which provides some reference for engineering analysis and design.(5)The mechanical model of coal gangue cemented filling is established by using particle flow software,and the influences of parameters of cemented filling body,such as the stiffness of cemented material,parallel tensile strength,cohesive force and friction coefficient,on the mechanical properties and structural failure characteristics of the filling body are analyzed from the meso level;the uniaxial compression process of gangue cemented filling body is reproduced and compared with the macroscopic test.It is found that the first damaged area of waste rock cemented filling is between the waste rock particles and cementing material.There were 41 graphs,22 tables and 86 references in this paper.