Research on surrounding rock control system of double roadway combined with roof cutting gob-side entry retaining and gob-side entry driving

Double-roadway tunneling technology can effectively relieve the mining‐replacement pressure associated with the combined use of double roadways and gob-side entry driving in traditional longwall panels, but it also introduces difficulties in maintaining the stability of the surrounding rock. In this study, numerical simulation, similar simulation tests, and field applications with in-situ monitoring are jointly adopted to investigate, under the combined layout of roof-cutting gob-side entry retaining and gob-side entry driving, the influence of the basic-roof fracture position above the gob-side entry retaining and the width of the coal pillar between the two roadways on roadway stability. The comprehensive analysis indicates that a reasonable interval coal-pillar width is about 8 m, and the key construction parameters of the pre-splitting roof-cutting scheme for the basic roof are: a cutting angle of approximately 75°, a borehole depth of about 8.2 m, and a borehole spacing of about 1.5 m. Compared with the conventional gob-side entry retaining without roof cutting, the optimized scheme yields maximum roof subsidence of about 445 mm and 421 mm for the gob-side entry retaining and gob-side entry driving roadways, respectively, and maximum (peak) sidewall convergence of about 496 mm and 319 mm, indicating that the deformation of the surrounding rock of the two roadways remains within a controllable range. The results show that the combined layout of pre-splitting roof-cutting gob-side entry retaining and gob-side entry driving has good application prospects for alleviating mining-replacement tension and maintaining the stability of the surrounding rock of small-pillar double roadways.