Study on Roof Activity Patterns and Control Mechanism of Roof Stability through Resistance-Increasing Effect of Roadside Support in Gob-Side Entry Retaining

Gob-side entry retaining with pillarless mining is an essential strategy for achieving efficient coal resource recovery and reducing roadway development. Its core technology lies in controlling the stability of the roof strata through an effective roadside support structure. The intricate interaction between the roadside support and the roof strata constitutes a key scientific problem restricting the development of gob-side entry retaining with pillarless mining. Through the analysis of roof activity patterns and stability, the primary modes and influencing factors of roof instability in gob-side entry retaining are identified. Using the FLAC ^3D numerical simulation method and considering the resistance-increasing effect of roadside support for roof control,this study reveals the influence mechanism of the early initial support strength of roadside support on the safety control of the roof in gob-side entry retaining. Specifically, the faster the resistance-increasing rate of the roadside support, the better the roof control effect. Based on the zonal characteristics of roof activity, the movement of the roof in gob-side entry retaining is divided into the development zone, the active zone, and the stable zone. In the development zone, the roadside support should achieve full contact with the roof and possess a high resistance-increasing rate to provide timely support and reduce the separation between the immediate roof and the main roof. In the Active Zone, the roadside support cannot alter the overall movement patterns of the overlying strata. While resisting dynamic pressure effects, it must possess a certain allowable convergence to accommodate the “deformation-controlled” behavior of the main roof. In the stable zone, the roadside support should exhibit high load-bearing capacity and structural stability to ensure the safety of the retained roadway throughout its service life. The research results provide a theoretical basis for the selection of roadside support materials and the differentiated design of zonal roof control in gob-side entry retaining.