Backfill mining alternatives and strategies for mitigating shallow coal mining hazards in the western mining area of China

The mining induced subsidence and strata deformation are likely to affect the stability of the aquiclude, resulting in loss of water resources in the mining area. In order to reduce the disturbance of coal mining to the overlying strata and to preserve the water resources in the coal mining area, the roadway backfill mining (RBM) method was trialed in Yuyang coal mine in Northern Shaanxi, China. Based on pressure arch theory and ultimate strength theory, a mechanical model was developed to analyze the stability of coal pillars. Then the maximum number of vacant roadways between the mining face and the backfilling face was determined according to the stability of coal pillar and filling body. The method to calculate aquiclude subsidence and deformation was also proposed. Furthermore, as indicated by FLAC3D numerical simulations, the maximum tensile stress subjected by the aquiclude was 0.14 MPa, which is smaller than its tensile strength; the horizontal deformation was 0.24 mm/m, which is also smaller than the critical deformation of failure. Field monitoring data demonstrated a maximum of 2.76 m groundwater level drop in the mining area after mining. The groundwater level was determined to be 4.45~10.83 m below surface, ensuring the normal growth of surface vegetation and realizing the water-conservation coal mining (WCCM).

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

Advances in Civil Engineering ◽

10.1155/2020/6876453 ◽

2020 ◽

Vol 2020 ◽

pp. 1-12

Author(s):

Baiyi Li ◽

Nan Zhou ◽

Wenyue Qi ◽

Ailing Li ◽

Zhizhong Cui

Keyword(s):

Coal Mining ◽

Mining Area ◽

Filling Ratio ◽

Surface Subsidence ◽

Integral Model ◽

Resource Exploitation ◽

Machine Material ◽

Deep Mining ◽

Backfill Mining ◽

Surface Subsidence Control

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.

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