High Slope Stability Assessment Of The Southern Section Of Lanshan Iron Mine Of Panzhihua

The iron mine of Lanshan in Panzhihua is typical of artificial open pit. Afternearly50years of mining, excavation has entered the stage of deeply surface miningand the mining depth increased year by year. Currently, the mine has formed a slopeof415m height. Ground elevation is1180m.the mine will eventually form an artificialhigh slope of550m height. However, it also has50-year term of service. Theengineering geological conditions of Lanshan mine are relatively complex. Joints andfissures are widely distributed. Slope stability issues directly affect their futureeconomic of exploitation even a threat to Human life and property safety.Combined with the actual situation of iron ore, Firstly, the article investigated theengineering geological conditions of the field area in detail. Combined withhigh-density electrical geophysical prospecting, this paper identified the adversefactors to the excavation stability existing in the area. That is fault fracture zone FXand hornblende schists weak interlayer ω6. With the help of3D laser scanningtechnology, we statistic jointed occurrence and its regional development lawaccurately. Finally, by the means of laboratory tests, we determine the physical andmechanical parameters of rock and soil and identify the various factors that affectslope stability analysis which provides the basis for the further condition.We take the measure of fuzzy comprehensive evaluation based on AHP and3DEC numerical simulation program to evaluate of the overall stability of the slopeand evaluate of the stability of a typical cross-section in the southern section atdifferent stages of excavation.Research results:Combined with the actual situation of iron ore, the article established the stabilitycriteria of sub-item rating scale factors. Based on the actual conditions of the highslope of Lanshan iron mine, the article judged the membership of individual factors.Finally, fuzzy comprehensive evaluation was carried out. Evaluation results: Undernatural conditions, each level of membership of slope stability factors is (0.240.250.210.190.11). Based on the principle of maximum degree of membership, The evaluation results are grade Ⅱ. The slope is in a relatively stable state. In extremerainfall conditions, Each level of membership of slope stability factors is (0.190.250.240.210.11). Based on the principle of maximum degree of membership, Theevaluation results are grade Ⅱ. The slope is also in a relatively stable state.3DECdimensional numerical simulation results show that the maximum displacement of theslope is2.4mm. the result shows that the slope is in a relatively stable state and itverifys the reasonableness of fuzzy comprehensive evaluation results.UDEC Simulation results show that rock excavation prompted toe stressconcentration. Outward displacement along the downslope, it formed a continuousplastic zone at the foot of the slope. With the deepening of the excavation, the plasticzone becomes larger, the displacement becomes larger. Excavating to1290m, due tounloading at the toe of the slope, the horizontal displacement focuses on the level ofexcavation, and mainly distributed in the lower part of the shallow, the maximumhorizontal displacement is2cm, the maximum vertical displacement is0.3cm.Excavating to1270m, the maximum horizontal displacement is2.4cm, the maximumvertical displacement is0.6cm. Excavating to1250m, the maximum horizontaldisplacement is up to4cm, the maximum vertical displacement is up to1.2cm.Displacement Monitoring curve shows the slope eventually reach equilibrium. Thisshows that these are normal strain deformation, the whole slope stability does not lose.The slope is basically stable state. The great displacement magnitude attention shouldbe paied for and we should take control measures, such as support, anchorreinforcement.