Determination of the movement and deformation areas of strata when exploiting longwall of Seam 11 under the open-pit mine at Ha Lam Coal Mine, Vietnam

Abstract

Exploiting the face under the finished open-pit area always has potential risks of unsafety. It can be the risk of water flowing into the face or the occurrence of water cracking and mud, which is a very dangerous phenomenon in mining. The larger the dimension of the influence area of exploiting the face is, the greater the risk of water problems entering the face is. Through the assessment and analysis of the coal exploitation at the synchronized mechanized face of Seam 11 located under the open pits that have finished exploitation at the Ha Lam coal mine, the article has determined the movement and deformation areas of strata in the surrounding area to assess the influence of water in the open pit into the face. In order to avoid the risk of water cracking, the impact of these risks on the workers’ safety and the exploiting process, the determination of the movement and deformation areas of surrounding rocks when exploiting the longwall face of the coal Seam 11 is very necessary for the Ha Lam coal mine. By collecting and analyzing geological conditions of the rocks around the face, combined with numerical modelling methods, the author has determined the dimension of the collapse and cracking areas when exploiting the face. The results of the research from this article have helped the Ha Lam coal mine take the initiative to choose and organize a rational mining solution. On that basis, it is possible to prevent the influence of water in an open-pit mine to ensure safety during exploiting the face of coal Seam 11.