Deformation Mechanism And Stability Analysis Of High Steep North Slope Of Jin Duicheng Mining Field

Shanan Xi Jin Duicheng molybdenum is the largest mine in China’s nonferrous metal, themining field has been excavated to form higher than200m high slope. Since the north slopeare in Yan Menao fault zone, north slope rock has been broken loose, developed secondaryfaults and joints, makes some steps collapsed, and local appeared serious phenomenon ofdeformation failure. If slope continue to excavation, will seriously affect the safety of themine production. It is necessary to study the deformation failure mechanism of north slopeand evalution of it’s stability.This paper studied the north slope of Jin Duicheng mining field. Through the datacollection, the filed exploration, indoor test and simulation method, studied the engineeringgeological conditions of north slope and Yan Manao fault zone, came to the deformationmechanism and failure mode of north slope, analyzed the stability of north slope withFLAC2D,finally put forward some suggestions of treatment measures, the main achievementis listed as follows:(1) There are four kind of tectonites in Yan Menao fault zone:cleavaged andesiticporphyriete, tensional breccia, piezotropy breccia and cataclasite.Yan Menao fault has thecharacteristics of multi-period activity, it is tensional in first, in the later period of piezotropyand compresso-shear.(2) The whole north slope will not downslide along the structure surface, in the sectionof piezotropy breccia outcropped, the single step has poor stability, and easy to instability andfailure. The upper slope will undraw along fault zone, lower along the maximum shear stressbelt cut out.(3) Simulated slope with FLAC2D software, considered the nature, long-term rainfall,long-term rainfall and blasting vibration of the three conditions, calculated the stability ofcurrent slope (1130m),the excavation to the platform of1010m and910m,Due to the slopehappened instability and failure when excavate to the platform of910m,we setted up wideplatform of30m,40m,50m in1130m platform, to re-analysis of stability for excavation to1010m platform. According to the simulation result, the factor of stability of current slope is1.22,the slope has poor stability, and the Fos is1.06in conditions of long-term rainfall and blasting vibration, the slope has basic stability. With the future excavation of the slope, thestability will decrease, even the whole slope will happen instability and failure, engineeringtreatment must be carried out in order to continue the excavation of production.(4) According to the result of FLAC2D,to improve the stability, we suggest to takemeasures of setting up wide platform in the local area, reducing blasting vibration and draingto the slope.