# Study on the Evolution Law of Overlying Rock Collapse Induced by Mining Based on BOTDR
## 1 Introduction  
During coal mining, the deformation, failure, and collapse of overlying strata are inevitable, leading to a redistribution of stress and strain. Therefore, rock movement and mining-induced stress-strain evolution are closely interconnected. Investigating the stress-strain evolution of overlying strata during coal mining is fundamental to optimizing coal mining technologies [1, 2]. To enhance the accuracy and efficiency of monitoring roof collapse during coal mining, researchers have introduced distributed optical fiber sensing technology into traditionalmonitoring methods. Compared to mechanical or electronic sensors, distributed optical fiber sensors offer advantages such as fully distributed measurement, long-distance transmission, and high sensitivity [3; 4; 5]. As a result, this technology has become a research hotspot in coal mining monitoring. In terms of its application in overlying strata deformation monitoring, [PERSON] and [PERSON] [6; 7] analyzed the coupling characteristics between optical fibers and rock-soil interfaces through pullout tests. [PERSON] [8] used fiber optic grating to study the coupling of loess deformation and developed a loess deformation prediction model. [PERSON] [9] utilized distributed optical fiber sensors to investigate coal seam deformation and failure mechanisms. [PERSON] [10] developed a strain-sensitive optical fiber sensor based on optical fiber sensing technology to monitor the strain evolution of surrounding rock in tunnels. [PERSON] [4; 11; 12; 13; 14] combined theoretical analysis with field optical fiber measurements to analyze the three-zone deformation characteristics of slope surrounding rock, identify the failure location of the key aquire layer, and determine the damage depth and stress-relief range of the coal seam floor after mining. [PERSON] [16] studied cantilever thin plates, establishing a correlation between optical fiber strain and deformation while proposing an error correction strategy, thus laying the foundation for optical fiber sensors in structural deformation monitoring. These studies demonstrate the significant potential of distributed optical fiber sensing technology in ensuring coal mine safety [17; 18]. Due to its cost-effectiveness, controllability, and visualization capabilities, laboratory-based physical similarity simulation has become an essential method for investigating overburden movement in coal mining [7; 19; 20]. Consequently, researchers have incorporated distributed optical fiber sensing technology into similarity simulation experiments to improve monitoring accuracy and applicability. For instance, [PERSON] [21] employed fiber Bragg gratings in an experimental model to detect rock deformation. [PERSON] [22] conducted similarity simulation experiments and compared optical fiber strain monitoring systems with digital image correlation (DIC) techniques to validate the coupling characteristics between rock and optical fibers. [PERSON] and [PERSON] [23; 24] investigated the strain curve variation patterns of horizontally and vertically deployed optical fibers and explored their relationship with the deformation, failure, and movement processes of overlying strata in the stope. [PERSON] and [PERSON] [25; 26] developed a model correlating roadway roof strata subsidence with optical fiber strain, confirming the feasibility and reliability of optical fiber-based monitoring in coal roadway roofs. In summary, distributed optical fiber sensing technology has been widely applied in coal mining monitoring, and significant progress has been made in investigating overburden movement and optical fiber strain monitoring. However, the intrinsic relationship between optical fiber monitoring of surrounding rock strain and stope overburden collapse remains insufficiently explored. Therefore, this study employs laboratory and similarity simulation experiments using distributed optical fiber sensing technology to investigate the strain evolution of surrounding rock and the overburden collapse mechanism.