Surface Subsidence Control during Deep Backfill Coal Mining: A Case Study

Deep resource exploitation is imperative, but it is facing with more complicated mining environment and more dangerous mining disturbances to induce the potential catastrophe process. Solid backfill technology, which can control the strata movement and prevent potential hazards, has been used as the primary method in deep mining for surface subsidence control and ecosystem protection. In this study, taking backfill mining area no. 930 in the Tangkou coal mine as background, the probability integral model was adopted to predict the surface subsidence at different mining depths and filling ratios. The filling ratio was designed for deep mining based on the regression analysis of the predicted surface subsidence results. The study shows that the backfilling ratio at the Tangkou deep coal mining area should be controlled at a level greater than 82.5%, and the mining damage to the surface under this condition was analyzed. Furthermore, control strategies for deep backfill mining are proposed in which the backfill density can be enhanced by optimizing the tamping machine, material composition, and tamping process. Finally, the measurement of the backfill mass and surface subsidence showed that the actual filling ratio was controlled at 82.57%, which ensures adequate protection of the surface buildings during the mining process.

Surface Subsidence Control Mechanism and Effect Evaluation of Gangue-Backfilling Mining: A Case Study in China

Comprehensive mechanization solid backfilling mining is a new technology developed in China for coal mining and surface subsidence control. Based on a gangue-backfilling project in the Yangzhuang Coal Mine, the characteristics of underlying strata and surface deformation were studied by similar-material simulation method. When the ratio of the sponge to foam was 1 : 3, the mixture can simulate well the deformation characteristics of gangues in the similar-material model. On this basis, the movement and deformation characteristics of the overlying strata caused by gangue-backfilling mining were studied. The findings indicate that compared with caving mining, the expansion coefficient of overlying strata, the interlayer fracture, and the subsidence value were smaller in backfilling mining, with the integral overlying strata subsidence occurring. Meanwhile, the reduction ratio of surface subsidence after backfilling mining was more than 85%, verified by the subsidence-monitoring results. The research outcomes in this paper have significance for coal resource exploitation of similar mines around the world.

New Technology of Surface Subsidence Control and Environmental Protection Research in Coal Mining Region

In combination with the geological conditions of Tie'er mining area in Tangshan coal mining, this paper not only analyzes the evolution of overlying strata structure in stope and the development law of overlying strata separation, also proposes a new continuous grouting technology with large flow and high concentration slurry. The industrial test showed that, when the grout-mining ratio of the whole mining area is 25.3%, the reducing subsidence ratio is 51.5%, the effect of reducing the surface subsidence is good. According to the chemical analysis of water quality ingredients of slurry, the test result showed, heavy metals contents in fly-ash slurry water do not exceed the standard, which has no bad effect on the fissure water in the bedrock.