| Founded in 1958,Pingzhuang West Open-pit Mine is located in the southeastern border of Chifeng area.As the first self-designed and built open-pit mine of China,it has formed a sunken open pit on the hillside with a slope of about 4.5km in trend from east to west and a width in inclination about 1.5km from north to south.Due to the mining of high-strength mineral resources for nearly half a century,the slope of the open-pit mine is unsTable,and there have been geological disasters such as slope landslides,small collapses and slope landslides of different scales.According to records since the construction of the mine,There were more than 70 landslides,of which top slope landslides accounted for half of the total numbers.According to statistics,the total amount of accumulated lost rocks,rock cuttings and topsoil exceeded to 4.2 million m3.A landslide occurred again in Pingzhuang West Open-pit Mine on April 17,2013.According to engineering geological survey,the azimuth projection area of the sliding body is about 94,000 m2 with the average thickness about 35m,and the volume about 2.79 million m3,which means it is a giant deep rock landslide.Although the top slope landslide did not cause any casualties in the open-pit mine,the open-pit mine suffered economic losses because it hindered the development of the production plan.The thesis relies on the "Pingzhuang West Open-pit Mine 4.17 landslide area landslide area and slope treatment optimization plan" and "Open-pit coal mine down-dipping soft rock slope instability time and space evolution mechanism and stability calculation method",On the basis of the 4.17 landslide case in Pingzhuang West Open,the basic characteristics and evolution process of the landslide,as well as the type of landslide warning and failure time prediction research are carried out.This paper first uses several comprehensive survey techniques,such as engineering survey,landslide feature survey and mapping,and landslide dynamic deformation monitoring,to find out the environmental engineering geological conditions of the Pingzhuang West Open-pit Mine,and clarify the geomorphic structure,shape characteristics,and perimeter development of the landslide.The distribution range and the stratigraphic sequence of the slope structure further clarify the geological structure of the landslide based on the description of the landslide overview.According to the comprehensive deformation monitoring results,the failure mode is analyzed,the mapping relationship between the monitoring information and the landslide disaster evolution stage is established,and the dynamic process of the landslide sliding is simulated by the meso-large deformation numerical calculation method.Secondly,based on the deformation characteristics and monitoring results,criteria are proposed and an early warning model established.Finally,a landslide time prediction method for the 4.17 project case of Pingzhuang West Open-pit Mine was proposed.The main research results are as follows:(1)Research on geological environmental conditions of the top landslide area of Pingzhuang West Open-pit Mine.The top slope of the Pingzhuang West Open-pit Mine has a relatively large elevation difference,and the inclination of the strata is opposite to the top slope,and the overall structure of the slope is anti-dip layered.Most of the top slope of Pingzhuang West Open-pit Mine is covered by the Quaternary,and some parts of the Neogene Pliocene basalt are exposed.The underlying bedrock is a regional metamorphic rock mixed with a variety of gneiss.the top slope stability Mainly controlled by the weak layers of the diabase roof A and A4,the weak structural surface of the A4 layer above the diabase and the joint fracture surface in the upper basalt rock mass form potential sliding zones due to shearing and crumpling.The sliding zone is composed of three parts:weak layer A,the measured back wall of the landslide and a continuous curved arc.The slip mode is a typical "folded landslide" in the cross section of the main axis of the landslide.The rock mass joints,fissures and weak structural planes are relatively developed.Combined with the displacement change rate of the 27 monitoring points arranged in the top slope landslide area,the research on the cause mechanism of landslide deformation and failure also provides a verification basis for constructing landslide warning and landslide time prediction models.(2)Numerical simulation of the dynamic process of 4.17 landslide in Pingzhuang West Open-pit Mine.The failure process of sliding in the 4.17 landslide case is analyzed by the discrete element numerical simulation method.In the dynamic analysis,the velocity field distribution cloud image and the energy field partial cloud image during the failure sliding process were obtained respectively.A band-shaped high-heat zone is obviously generated near the sliding zone,which continuously expands to the bottom of the slope along with the sliding process of the sliding body,and the heat gradually disappears as the process of landslide ends.During the entire sliding process,the gravitational potential energy of the slope system converts into heat,kinetic energy and elastic potential energy during the instantaneous movement of the landslide;as the sliding body moves downward,the gravitational potential energy continues to decrease and the kinetic energy gradually increases.The kinetic energy of the landslide in the acceleration phase is the main source of energy input,and the frictional heat of the sliding belt dissipates the kinetic energy during the entire landslide movement.(3)Combining the quantitative data provided by the 4.17 landslide dynamic deformation monitoring of the Pingzhuang West Open-pit Mine,based on the classic criterion of acceleration a>0 in the landslide dynamic monitoring sample path,the landslide criterion is carried out from the perspective of the random process.A new characterization,based on the Markov chain decision theory and the classification idea of the system clustering algorithm,regards the displacement velocity in the landslide process as a Markov process,and uses cluster analysis to convert the GPS speed observation signal into a state signal.The goal is to study the sequential decision-making process in which the displacement velocity state transition probability is the subject and the displacement change rate state is the object,and a systematic clustering coupled weighted Markov chain landslide warning method is proposed.For the existing landslide warning theories and methods generally exist Model prediction performance is low,the error rate of output source is high,and the delay in sending early warning information is obvious.While avoiding the delay deviation in the transmission of landslide warning information,it also considers the improvement of the signal to noise ratio of the early warning model.The ability and decision-making coverage credibility level and many other requirements,proposed to use the early warning area sensitivity,early warning accuracy rate and prediction consensus rate output evaluation function indicators to test the correctness and effectiveness of the landslide early warning model.(4)By analyzing the characteristics of the deformation time curve of the 4.17 landslide in Pingzhuang West Open-pit Mine,it is proposed to quantitatively analyze the displacement change rate curve based on the VMI model,and construct three filter model pairs of short-term smooth transition,long-term smooth transition and exponential smooth transition.The representative monitoring point data is filtered and analyzed;the accuracy and practicability of the model under the influence of strong and weak noise and under different displacement scales are compared;finally,a hierarchical warning is established. |
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