Research On 3D Modeling, Stability And Treatment Of Complex Cavities Under Open-Pit Mine

In some open-pit mines of China, there are large amount of unprocessed cavities left due to small-scale underground mining before surface mining and private mining. Because of the influence of ground pressure, rock weathering and blasting vibration, most of the cavities collapsed in different degrees. Varied size and height of cavities result in the difficulty of the determination of the location and size of the cavities. In the progress of mining in the open-pit, those irregular cavities with complex shape became a serious threat to the safety of mining personnel and equipment. Therefore, for the open pits with complex and irregular cavities, some key problems including 3D visualization of cavities, the stability of cavities, the effect of the blast load on the cavity stability, effective measures of the cavities treatments should be deeply investigated. In the view of this, the main contents of this paper are as follows:1,Collecting, processing and analyzing the original data of the cavities in the open pits of Dabaoshan Mine. Building 3D solid models of the surface, cavities, and the mining as a whole model by MIDAS-GTS software, so that the three-dimensional space relationship between cavities and mine can be obtained.2,Analysising and evaluating the stability of cavities under the action of the step excavation process with simplified numerical model. Through the analysis of the stress, displacement, plastic zone of the cavities, the effects of excavation of the steps on the stability of cavities can be obtained. 3,Investigating the stability of cavities under blast loading by numerical method.The effects of the amplitude and the location of blast loads effect on the displacement, velocity, acceleration of rocks mass around cavities can be obtained.4,Cavities under the open-pit limit of Dabao Mine, according to the characteristics of ore and rock, the difficulty of treatment. By considering the angle of the factors of actual production, the results of numerical simulation, and the evaluation of the cavity stability, a standard for judging whether the cavities need to be treatment is proposed.The principles and the effective steps of the cavities treatment are concluded.