A Study On Evaluation System And Stability Analysis Of Rock Slope In The Open Pit Of Daye Iron Mine

Daye iron mine is the famous domestic iron mine, After the last50yearsexcavation, east open-pit has formed a relatively rare slope of high and steeprock in length, width and feet. Because of the complex geological structure,development joints and fissures, strongly weathering altered rock of rock, withthe mining from opencast to underground, the slope often occurred collapse andlandslide with all size of deformation and failure during the constant processof extending to the deep mining. Especially the collapse area around the toe ofslope and the F9landslide in the north of open pit which dominated by F9faultand F9branch fault, it seriously affects the safety of mining personnel andequipment in the bottom of the the east open-pit of Daye iron mine, and alsothe next step construction of the mine Park. Therefore, the analysis andpredicate the stability of rock slope through the established stability evaluationsystem of rock slope in the open-pit of Daye iron mine has importantsignificance.On the basis of fully studying of previous data and research results, thispaper established the evaluation system of rock slope in Daye iron mine bydirected at the actual situation of east open pit slope, and taking a typical slopesection in VI area as example, with the use of evaluation system to analysis andpredict the rock slope stability in this area. The main thesis and conclusions ofthe study are mainly the following points:（1）Research of engineering geology environmental. The research ofenvironment physical fields, geological structure field, rock mass structure fieldof rock slope in Daye iron mine can be completed by the means of engineeringgeology investigation, interior data analysis and so on. And focuses on theinvestigating and analysis of engineering geological characteristics,underground mining and ground subsidence, which provides the basis for studies of the structural analysis of slope and the numerical simulation about thedeformation and failure in VI area of north Shi zhi hill on the east open pit.（2）Research of stability evaluation system and analysis method of rockslope. By analysis the influence factors of rock slope stability in detail,summarize and conclude the failure mode of rock slope, and classified the rockslope structure to identify the potential failure mode with different index toestablish the stability evaluation system of rock slope, elaborated the analysismethod of slope stability with advantage and defect.(3) The set up of stability evaluation system of rock slope in Daye ironmine. Through the analysis of morphological characteristics、scale of rock slopein VI area, the main influence factors of slope stability has determined asformation lithology, geological structure and underground mining, then classifyand calculate the weights of the three indexes, according to the stabilityevaluation system of rock slope, the stability evaluation index system of rockslope and stability evaluation system of Daye iron mine is set up.(4) The finally stability analysis of rock slope in VI area.According to the stability evaluation system of rock slope in Daye ironmine, the corresponding method which specified to the main three factors canbe used to analysis the stability of rock slope in VI area.①analysis of rockmass structure with stereographic projection method; the analysis results showthat most of the joint surface have small influence on slope stability whichnearly intersected with the slope surface, as the potential structure surface, jointJ4, J5and J6are bad for the slope stability, and F9fault is the main weaknesssurface of slope which go against with the slope stability;②simulate thestress、strain and plastic zone change of slope in underground mining withFLAC3D; in the original state, the maximum principal stress of slope is15MPa,the minimum principal stress is12.5MPa; when mining to the level of▽-60m,▽-84m,▽-120m ore section, the maximum principal stress of slope has beenincreased from27.6MPa to32.4MPa, the minimum principal stress has always been kept at0, the shear stress increases first and then decreases, with theincreasing mining depth the surrounding rock stress have a rapid increase, but toa certain depth and range the amplification slow down very quickly; Though thebackfilling have very good effects on slope stability such as the shrink of plasticarea, the low effect of backfill to reduce the range of plastic zone in surroundingrock, the yield region of elastic are gradually expanded and symmetricallydistributed on the left and right side with the increasing mining depth, the shearfailure emerged in the broken zone of fault and the both bottom sides of hollowarea, and the tensile failure emerged in the surface of open pit slope, yet thebroken zone of fault is completely in the plastic state;③In addition, itcalculates the slope stability factor of the slope in VI area under the current statethrough the Geo-slope software and searches for the most dangerous slipsurface of the slope.