Dynamic Evaluation Method and Application of Slope Stability in Small and Medium Open-pit Mines

Author:Xiao Hai Ping

Supervisor:guo guang li


Degree Year:2019





With the increasing demand for mineral resources in the social economic construction,because of the lack of management and overexploitation on the mines(especially small and medium mines),a variety of large and small geological disasters which have caused major casualties and property losses have been happened in the open-pit slope.So,the effective analysis and evaluation of the slope stability is an important technical means to ensure the management and control of the mine safety production,and also a very important research content in the slope engineering.It provides an important technical basis and policy-making support for the disaster prevention,disaster reduction and disaster relief of the mine slope.In view of this,this paper takes the HP1 slope of the Yuebao Open-pit Mine as the research object,comprehensively uses the technical means and methods such as theoretical analysis,field measurement,mathematical modeling,numerical simulation,comparative analysis,and case verification to solve the excavation of the main influencing factors(evaluating indicator)on the slope,the construction of the risk dynamic evaluation model on the slope,the coupling analysis of the influence factors on the slope stability,repair of abnormal data in deformation monitoring and the analysis of slope prevention and control which have been studied and discussed,and the following research results are mainly obtained.1)Qualitative screening and quantitative screening are combined to excavate the evaluation index of the slope stability.Taking Yuebao Open-pit slope as the research object,on the basis of the qualitative screening,this paper establishes an improved grey relational degree evaluation index mining model taking into account the efficiency coefficient β and reliability coefficient ρ,which improves the validity,stability and reliability of the evaluation index,lays a foundation for the establishment of dynamic evaluation model of slope stability,and also provides a guarantee to improve the accuracy of the slope stability evaluation.On this basis,the strength reduction method of UDEC numerical simulation is adopted,and the convergence of calculation is taken as the basis to judge whether the slope is unstable or not,and the influencing mechanism is revealed,which provides a theoretical reference for the treatment of the slope in the later stage of the paper.2)It overcomes the fixed weight shortcomings of the influencing factors on the slope stability evaluation models in the past.In this paper,the rainfall index factors are taken as the research object,a dynamic variable weight model based on the information entropy is constructed,and the index weights of the factors under different monthly maximum rainfall are calculated.The results show that the influencing factors weights of the slope stability is no longer a fixed value under the different monthly maximum rainfall,but presents a non-linear and dynamic change law,and there is a strong correlation among the maximum monthly rainfall,internal friction angle and cohesion,which lays a foundation for the establishment of the dynamic evaluation model of the slope stability.3)On the basis of the dynamic variable weight model established,the variable weight risk dynamic evaluation model of unascertained measurement is constructed,and the risk importance index q which been quantitative evaluated the slope risk degree is proposed.The results show that the risk importance degree of the slope is gradually increased with the increasing of the maximum monthly rainfall,and the risk grade is increased from grade III to II,that is,the possibility of slope disaster has been raised from general to higher state,and the evaluation results are more consistent with the actual situation of the HP1 slope of Yuebao Open-pit Mine.In addition,taking the two factors of hydrology condition and underground water as the experimental object,the coupling degree between the influencing factors is quantitatively analyzed by introducing the slope risk importance degree q and its relative change rate R(q).The results show that there is a certain weak coupling between hydrology condition and underground water.4)Taking the HP1 slope of Yuebao Open-pit Mine as the research object,the deformation monitoring scheme is designed and implemented to obtain the three-dimensional coordinate data of monitoring points.On this basis,the anomaly of monitoring data is checked by using the 3σ criterion,and the anomalous monitoring data are discarded or eliminated.At the same time,aiming at the abnormal data(including missing or excluded abnormal data)in deformation monitoring,the paper has proposed a spatio-temporal interpolation method for anomalous data of slope deformation monitoring considering point change in order to improve the continuity and integrity of the slope monitoring data.This method is simple,easy to understand and feasible.It can be used for mine survey technicians to solve the problems of abnormal data processing of deformation monitoring.It has important theoretical value and practical significance for guiding the layout of deformation monitoring points and processing abnormal monitoring data.5)Based on the continuous and complete deformation monitoring data obtained by the above spatio-temporal interpolation method,the stability and deformation trend of the slope are analyzed from multiple angles and directions by the method of combining displacement,displacement rate and displacement vector azimuth angle.The change direction of the slope is defined,and the deformation displacement and deformation velocity are calculated.It plays a guiding role in the safety production and management of the mining enterprise,and also provides theoretical basis and important reference for the analysis and research of other slopes and related fields.6)In order to prevent the further disaster of the HP1 slope,two different schemes and measures are put forward,and the investment prediction costs of the two schemes are calculated respectively,and then the comprehensive comparison is carried out to determine the preferred scheme for the slope prevention and control.The dynamic evaluation method of slope danger degree and the safety factor of slope stability are used to analyze and calculate the danger grade and safety factor Fs of HP1 slope under different working conditions.The evaluation grade is IV(the danger of slope is low),and the safety factor Fs is 1.315,which meets the requirements of slope safety design code.The two methods complement each other.By filling and verifying,the stability state of the slope is analyzed more accurately,which provides a reference for guiding the safe production and prevention of the mine slope.The dissertation has 59 figures,31 tables and 188 references.