Study On Security Management And Control Of Complex Gob At Open Pit Mine Turned From Underground

Nowadays there are many open pits which were underground mines in the past.So there are usually many gobs which have different figures, overlap up and down.They usually are not located accurately in space. Due to self-weight, weathering andblasting, the stability of rock around gobs decreases constantly. Cracking, deformationand collapse could occur at uncertain time. It is a dangerous thing for the production ofsurface mining. This is a major hidden danger to production of this surface mines.With the view of existing safety problems caused by those gobs, there is asolution proposed in this paper. Using geology, computer graphics,3D construction,visualization, rock stability analysis methods and safety system engineering and so on,many fields studies on gob has been proposed, for instance, detection and positioningof complex gob, data preprocessing, ore body modeling, stability analysis of the safetyisolation in gobs, real-time monitoring ground pressure at risks area and safetyproduction management and control above some typical gobs so on.The results of gobs in this paper have been developed as follows:1. The detection and positioning of group underground gobs. With the view ofunknown gob’s position below the bench, a seismic wave inversion imaging method hasbeen taken to get the accurate position and roughly outlines of gobs. When the accuratepositions have been obtained, the genetic algorithm is used to calculate the detectionholes’ position. Then three-dimensional laser scanning is used to get the gob’s outlinedata. Lastly, the gob boundary of3D points cloud database was built and the outlinedata is used to construct gob space model2. The processing of gob point cloud data. Firstly, all the gobs point cloud data is divided into many horizontal planes according to height. The point data near thehorizontal line should be kept and others between two different horizontal lines areignored. All the kept point data is seen as the same horizon. The least squares curvefitting method is adopted to reduce discrete point cloud data. Secondly, the sphericalprojection uniform grid and median filtering algorithm is adopted to reduce the floor’sand roof’s point cloud data. After the above processing, a lot of point’s data is ignoredand a new3D gob point data collection can be built to reflect the real constructing ofgobs.3. The construct of three-dimensional complex gob model. Using the reduced floorand roof point data and different horizontal point collection, a triangulation grid methodis proposed based on Triangulated Irregular Network. The triangulated algorithm ofadjacent horizontal outline and the inner triangulated algorithm in the gob’s floor androof are put forward. Especially, the triangulated methods of irregular shape, concavesection lines and complex concave section inside are proposed. The3D complex gobmodel was built. Finally, a Boolean operation method for complex group gobs isproposed to calculate solid model based on Oriented Bounding Box.4. The stability analysis of gob’s roof safety isolation. Considering the weight ofheavy equipments, rock and the upper loose gravel and the vibration of blasting in theopen pit, a numerical simulation analysis method is proposed to analyze the stability ofcomplex gob in space. The gob’s roof safety isolation layer stress, displacement andchanges of plastic zone are studied in this paper. The analysis results are provided tokeep production safe.5. The thickness calculation of gob’s safety isolating layer. For the gobs whichhave simple construct in space, traditional theoretical calculation methods andnumerical analysis are used in different thickness roof. The roof safety thicknessdiagrams of uncover and normal gob size is developed. In daily production, the gobinformation is collected firstly and then the gob’s span is calculated. The safetyisolation thickness can be calculated soon. Then the calculated thickness is compared tocurrent thickness and the manager can make a decision whether the production can becontinued.6. The real-time monitoring and warning of gob ground pressure. Based on all digital micro seismic technologies, the gob ground pressure can be monitoring in realtime. Then the pressure data is processed by wavelet theory. The time series data ofaccumulative apparent volume is predicted by trend method. On the basis, thepre-warning method is designed and developed. The automatic warning is realized assoon as possible based on monitoring data.7. The safety management, planning and control of complex gobs. With the view ofmining and gob management in Sandaozhuang open pit, the framework of safetymanagement, planning and control is proposed. The gobs of open pit are divided intodifferent area to manage. Using the technologies of positioning and detection, solidmodeling, stability analysis of roof, safety thickness calculation, monitoring andwarning and so on, mining activity and gob processing can work simultaneously. Theapplication has shown that remarkable economic and social effects have been achieved.The safety management and control of complex gobs can be applied in other similarmine.