Calculation Of Critical Fluid Injection Strength Of Ionic-type Rare Earth Mine Considering Spatial Variability Of Orebody Dry Density

In this paper,the ion-type rare earth mine in Wuping mining area of Longyan City,Fujian Province,is taken as the research object.A line parallel to the ridge line and B line perpendicular to the ridge line are arranged in the mining area to carry out density sampling experiments at different depths.The spatial variability of dry density and pore ratio of rare earth ore body is analyzed by using the knowledge of geostatistics.On this basis,the effects of dry density and pore ratio on saturated permeability coefficient,soil-water characteristic curve and shear strength are analyzed.Finally,based on GeoStudio software,the critical injection strength and potential landslide depth of rare earth mines under different dry densities,as well as the critical injection strength and potential landslide depth of rare earth mines considering spatial variability of ore body dry density,are calculated respectively.The comparison and analysis with field monitoring data show that the spatial variation of ore body dry density is taken into account when calculating critical injection strength of rare earth mines.Necessity of the opposite sex.The following conclusions are drawn:(1)Dry density and pore ratio of rare earth orebodies have moderate spatial correlation at different depths.With the increase of sampling depth,the range of spatial variability of dry density and void ratio in line A increases with the increase of sampling depth.The range of dry density increases from 23 m to 73 m,and the range of void ratio increases from 38 m to77 m.The range of dry density in the direction of B line keeps about 34 m,while the range of void ratio increases gradually from 40 m to 70 m.(2)When the sampling depth is not more than 7 m,the equivalent dry density of ore body increases with the increase of depth,and the equivalent pore ratio decreases with the increase of depth.When the sampling depth is more than 7 m,the equivalent dry density and the equivalent pore ratio of ore body with A and B lines tend to be stable.(3)With the increase of dry density of ore body,the critical injection strength of mine decreases nonlinearly,and the potential landslide depth decreases exponentially.The dry density of ore body increases from 1.35 g/cm~3 to 1.45 g/cm~3,and the potential landslide depth of mine decreases rapidly from 5.64 m to 1.32 m.When the dry density of ore body is greater than or equal to 1.45 g/cm~3,the potential landslide depth of mine is basically stable at about1.2 m.(4)When the injection area is 55%,the actual average injection intensity is 0.25 m~3/(m~2d).When the density of ore body is assumed to be uniform,the average dry density of ore body at all depths is taken.The critical injection strength calculated by the model is 0.38m~3/(m~2 d),which is larger than the actual critical injection strength of field mine,and the error is as high as 56%.When considering the spatial variability of ore body dry density,the ore body is divided into six layers according to the on-site sampling method.When the dry density of each layer is taken as equivalent dry density,the critical injection strength of mine is 0.21 m~3/(m~2 d)with an error of 16%.When the dry density of each layer is taken as average dry density,the critical injection strength of mine is 0.31 m~3/(m~2 d)with an error of 24%.This shows that the calculation is based on the calculation.It is necessary to consider the spatial variability of the dry density of ore body when the critical injection strength of mine is used.