Abstract:
The shallow-buried coal seams in the Shendong mining area exhibit significant geological heterogeneity. When the traditional method based on an average dynamic load coefficient is used for hydraulic support selection, it fails to accurately reflect the actual load distribution, which may result in inappropriate design of working resistance, induce instability of the support–surrounding rock system, and restrict safe and efficient mining. Taking the
22309 working face of Halagou Coal Mine as the engineering background, this study aims to reveal the controlling mechanism of geological heterogeneity on the dynamic load coefficient and to establish a prediction model suitable for such conditions, providing a theoretical basis for rational hydraulic support selection. Field measurements and theoretical analysis were combined in the research. The influence of bedrock thickness and burial depth in different sections on the dynamic load coefficient was analyzed, and the adaptability differences of hydraulic supports under varying geological conditions were evaluated. Based on the energy equivalence principle and the geological characteristics of “shallow-buried, single key stratum,” the released energy from the rotation of the fractured key stratum was treated as the dynamic load source. A dynamic load coefficient prediction model (DP model) integrating burial depth, advancing length, and bedrock thickness was established, and the Levenberg–Marquardt algorithm was applied to identify the model parameters. The results indicate that the dynamic load coefficient of the 22309 working face presents a stepped distribution, with 1.10 in the first section and 1.21 in the second section, leading to a 5.5% higher safety valve opening rate in the latter. The prediction errors of the DP model for the two sections were 8.95% and 1.59%, respectively, with prediction accuracy improvements of 8.14% and 4.86% compared with the traditional method. When applied to the 22315 working face, the predicted dynamic load coefficient was 1.202, with only 0.98% error relative to the measured value. The required support resistance was calculated as
10165.2 kN, and the ZY12000/25/50D hydraulic support was selected accordingly. Field monitoring confirmed the stable operation of the support system. The DP model can accurately predict the distribution of dynamic load coefficients in shallow-buried coal seams under heterogeneous geological conditions using commonly available geological parameters. It has clear physical significance, achieves high prediction accuracy, and overcomes the limitations of the traditional average method.