Study On The Influence Of Leaching Time On Slope Stability Of A Rare Earth Mine

Nowadays,the mining technology of in-situ leaching is generally adopted in the rare earth mines.But the research on the change of the stability of rare earth mine slope with the leaching time changing is not enough.This paper takes a rare earth slope of an ionic rare earth mine area in Dingnan County as the research object.Through borrowing the soil from the mine and making the simulating column leaching tests in laboratory,this paper measures the physical and mechanical parameters of the rare earth ore in different leaching time and studies the influence of leaching time on the physical and mechanical properties of the samples.And then this paper analyzes the effect of leaching time on slope stability.On the basis of laboratory tests combined with several common methods of current slope stability analysis,this paper selects the No.V ore body as the research object to calculate the safety factor of the rare earth slope after different leaching time and and discusses the applicability of different slope stability analysis methods in analyzing the stability of rare earth mine slope.Through the numerical simulation on the slope stability of the ionic rare earth mine in Dingnan County by using the finite element software FLAC~3DD to get the change of the stress,strain and plastic zone of rare earth slope with the leaching time changing,this paper analyzes the influence of the leaching time on the slope stability.The main conclusions are as follows:(1)With the increase of leaching time,the change of physical and mechanical parameters of ore is obvious that the water content increases about 18%;the density increases from1.7g/cm3 to 2.1g/cm3;the porosity decreases by about 0.04;the nonuniformity coefficient Cu of the sample decreases from 4.18 to 3.97;the coefficient of curvature C_C increase from 0.48to 0.54;the grain composition becomes worse;the cohesion reduces by more than 60%;and the internal friction angle increased by about 8 degrees.The slope stability of rare earth with leaching time growth decreased continuously.(2)This paper simplifies the geometric model of the slope according to the geological data combined with the test results of different leaching time after shear strength parameters and solve the safety coefficient after the test in different leaching time.According to the geological data,the geometric model of the slope is simplified to solve the safety factor of the slope after different leaching time combined with the shear strength parameters with different leaching time testing in the laboratory.The result shows that after 4 days of leaching,the safety factor of slope is less than 1.15,and the slope stability is poor.With the injection of liquid,the monitoring of the slope state should be strengthened,and the amount of liquid injection should be reduced.(3)About the calculation of the safety factor of rare earth mine slope,on the one hand,the safety factor getting from Janbu Method is more conservative which is better to reduce the risk of slope landslide.On the other hand,when using Janbu Method,the sliding surface can be arbitrary shape not to assume arc surface.The upper part of rare earth mine slope is soil,and the lower part is rock.The softness and hardness change greatly,which decides that the sliding surface is not standard arc surface.So the Janbu Method is much more adopted in analyzing the stability of the rare earth mine slope.(4)This paper uses the software FLAC~3D to make a time domain simulation of rare earth slope dip injection.With the increase of leaching time,the shear strength parameters make a reduction according to the results of the sample testing in laboratory in different leaching time.This paper gets the changes of the slope stress field,strain field,displacement field and plastic zone with the leaching time.The result shows that,with the leaching time increasing,the rare earth slope develops from stable state to unstable state.After 4 days of leaching,the shear stress of the landslide zone increases obviously,and the penetrating plastic zone of the slope is formed,which shows that the rare earth slope after leaching occurs slope instability easily.