Spatiotemporal correlation of multi-depth rock mass deformation and mining-induced subsidence: A case study of the Shagoucha Coal Mine

Abstract

To address the insufficient understanding of the dynamic coupling between surface subsidence and multi-depth rock mass deformation induced by underground mining, this study focuses on the 520109 working face of the Shagoucha Coal Mine in Shaanxi Province. Most existing subsidence prediction models rely heavily on surface deformation data and often overlook the temporal evolution of deep rock mass responses, limiting their predictive accuracy under complex geological conditions. In this context, we implement a fully integrated GNSS-borehole monitoring system to obtain high-frequency continuous GNSS observations and internal deformation time series at three key depths (14 m, 92 m, and 132 m). To reveal the dynamic correlation between strata deformations and surface subsidence across multiple time scales, cross-wavelet transform (XWT) analysis is applied to quantify both amplitude and phase relationships in the time-frequency domain. The results demonstrate that surface subsidence consistently lags behind deep rock mass deformation, with the deepest monitored stratum (132 m) showing the earliest and largest deformation. The 92 m layer (primary subsidence deformation zone) also displays a leading response, particularly in high-frequency bands, indicating its role in stress redistribution and transmission. In contrast, the shallow 14 m loess layer exhibits a lagging and hydrologically sensitive behavior, responding passively to overlying subsidence. These results highlight the stratified and frequency-dependent nature of deformation evolution, emphasizing the significance of deep rock mass signals as early indicators of subsidence progression. By integrating multi-depth deformation monitoring with time-frequency correlation analysis, this study provides novel insights into the temporal hierarchy of mining-induced subsidence. It provides theoretical support for refining subsidence prediction models and early warning systems. Compared with previous studies that focus primarily on surface or single-depth data, our approach provides a more comprehensive framework for interpreting the spatiotemporal dynamics of stratified deformation processes in mining areas.

Keywords

Mining-induced subsidence / GNSS / Deep rock mass deformation / Stress adjustment / Cross wavelet transform (XWT) analysis / Time-frequency correlation

CRediT authorship contribution statement

Dongdong Cao: Methodology, Conceptualization. Jun Zhang: Data curation. Ming Li: Project administration. Baoqiang Chen: Formal analysis. Jia Li: Investigation. Xiaolong Wu: Writing - original draft.

Author agreement and Acknowledgement

All authors agree for this publication. The authors would like to express their sincere appreciation to the editorial board and anonymous reviewers for their constructive comments and valuable suggestions, which have greatly improved the quality of this manuscript.

The authors declare that there are no conflicts of interest regarding this publication.

Declaration of competing interest

The authors declare the following financial interests (e.g., any funding for the research project)/personal relationships (e.g., the author is an employee of a profitable company) which may be considered as potential competing interests: Dongdong Cao, Jun Zhang, Ming Li, Baoqiang Chen and Jia Li are currently employed by China Coal xi ‘an Design Engineering co., Ltd. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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