Research On The Key Technique Of Stability And Safety Control Of The Large Dump In Open-pit Mine

The landslide and debris flows of the dump is related with the safety production of the mine, people’s lives and properties and the environmental protection. As a very common engineering disaster, the unstable landslide of the dump poses a great threat to the high-efficient mine exploit and safe operation. So it will be great scientific research significance and engineering application value to do further research about the dump slope stability and landslide control technique. This thesis takes the second phase of copper mine dump in Jiumen Jiangxi Province for a case study, based on the methods such as limit equilibrium theory, reliability theory, finite difference theory and discrete element theory, an efficient dump stability analytical method and landslide control measures were established to analyze the dump slope stability reasonably and operate production safely by means of field research, laboratory tests, numerical simulations and theoretical analysis. The main research results are as follows:(1) The sensitivity factors affecting the global stability of dump slope were internal friction angle of spoil, earthquake affecting coefficient, mixed spoil cohesion and unit weight in accordance with their significance.(2) The limitequilibrium and reliability analysis indicated that static safety factor and failure probability of the characteristic section E-E of slope were1.050and14.460%respectively at the end of dumping, while the safety factor decreased to0.946with increasing failure probability of53.160%under the impact of earthquake with intensity of7degree. In addition, static safety factor of the slope obtained by strength reduction method was1.07. Hence, the result showed that the slope was mainly stable at the end of dump with low storage of safety factor, which led to contingent landslide in static conditions still.(3) The local strength reduction based on particle flow code showed that the static safety factor of slope in unstable failure was1.12. During the slope failure, micro-factures produced along central section of slope body were in coalescence to slope crest gradually, and expanded towards the slope toe of second bench until penetrated through the slope and developed into interior landslide belt composed of micro-factures.In this process, the tension fracture continued the leading dominance, and the rupture magnitude of acoustic emission caused by landslide distributed in range from-2.47to-4.24. (4) An evidentdecrease in stability of dump slope was caused by different rainfall infiltration such as continuous heavy rainfall and short rainstorm, furthermore, safety factors of the characteristic parts without other improvement and controlling were generally less than those in specifications. On the condition of continuous heavy rainfall, gross head distribution of earth-rock aggregate discharged by upside slope in the later stage was impacted by rainfall infiltration obviously while gross head distribution of earth-rock aggregate dischargedin the earlier period was not. On the condition of short rainstorm, gross head distribution of earth-rock aggregatedischarged by upside slope in the initial stage was impacted by rainfall infiltration, which was not changed obviously as the developing of rainfall. It is due to excessive rainfall capacity in a short time that most rainfall losses along slope surface rather than infiltrate into slope body.(5) The treatment of securing stability by using "rail anti-slide plies+classified dumping", which was of significance to improving the stability of dump slope, and the static safety factors obtained by limit equilibrium and strength reduction were1.18and1.31respectively.Aiming at dump stability analysis and disposal measures of safety, the following innovative achievements have been obtained in this paper:(1)A set of reliability analysis using Latin Hypercube Sampling is established.(2)The local strength reduction method is established based on particle flow theory, and the acoustic emission simulation method is established based on Moment Tensor Theory. Based on these methods, the spatial evolution and the fracture mechanism of the dump slope destruction are investigated from meso-scale.(3)The traditional limit equilibrium theory is modified by the the saturated-unsaturated seepage theory and slope stability analysis theory, which is adapt to the sliding stability analysis of saturated-unsaturated soil. Based on this method, the slope stability in different rainfall condition such as continuous heavy rain and short-time rainstorm is analyzed and the law of effect of rainfall and seepage on the slope stability is revealed.(4)The rail anti-slide piles and classified dumping, which are the safety measures of dump slope stability, have been proposed.The research methods and relative achievements of this paper have significant research sense and practical application value, and they can be function as references for the the research and safety measures of dump slope stability.