# Review on Engineering Application Status of Gob-Side Entry Retaining Technology in China
## 5 Conclusions  
This work statistically summarized the current application status of GSER technology based on 587 practice cases in China, and then the applicable geological conditions and optional technical parameters of GSER technology were clearly presented. And the development status in China and the existing challenges of GSER technology were also systematically described. The following conclusions were drawn:  
(1) After more than 70 years of continuous research and engineering application, China's GSER technology has formed a relatively complete theoretical and technical system. GSER technology can be divided into two main modes: GSER with entry-side filling and GSER with cutting roofs. In recent years, there has been a growing inclination towards amalgamating and integrating these two modes of GSER.  
(2) The application of GSER engineering projects and its technical characteristics indicate that this technology is currently mainly applicable on-site for near horizontal and gently inclined coal seam conditions with an average burial depth of less than 700 m, an average thickness of 1-3.5 m, and an average dip angle of less than 25\({}^{\circ}\). The entry-side structure construction mainly adopts concrete filling and presplitting roof-cutting methods, and the entry-side filling width is generally 1-3 m. The cross-section of the retained entry is mainly rectangular, and the length of the retained entry generally does not exceed 1000 m. The relevant data provide a reference for the applicable geological conditions and optimal technical parameters for the effective implementation of GSER technology in coal mines and the prevention of safety hazards and significant economic losses caused by its failure.  
(3) Although current GSER technology has been successful and widely applied in coal mines, it still encounters many challenges in dealing with complex engineering geological conditions. For instance, the insufficient adaptability of the retained entry surrounding rock control technology and the imbalance between the entry retaining speed and the advancement speed in working face need further research and solutions. In particular, an intelligent GSER technology system compatible with intelligent construction urgently needs to be innovated.  
Conceptualization and Methodology, Y.Z.; writing--original draft preparation and writing--review and editing, Y.Z., J.D. and Q.C.; visualization, Y.Z., J.D. and Q.C.; data curation, Y.Z. and J.D.; funding acquisition, Y.Z.; supervision, Y.Z. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Natural Science Foundation of China (52274146), the National Key Research and Development Program of China (2023 YFC2907600) and Key Research and Development Program of Xinjiang Uygur Autonomous Region (2023B01010).  
Not applicable.  
Data Availability StatementData are contained within the article. Further inquiries can be directed to the corresponding author.  
The authors would like to express their appreciation to the authors who published the papers about 587 application cases of gob-side entry retaining in China from 2000 to 2024, without the data in their published papers, there would be no presentation of this paper.  
The authors declare no conflicts of interest.