In view of the complex stress environment of the underlying roadway and the difficulty in ensuring the stability of entry retaining under the combined action of the goaf and the residual coal pillar, this paper takes the auxiliary intake roadway of the 8307 working face in Xinjing Mine as the engineering background and carries out research focusing on two aspects: the determination of the pressure-relief environment beneath the goaf and residual coal pillar, and surrounding rock control through roof cutting and pressure relief. Two conditions, namely the structural basis and the stress basis, are proposed for determining whether a roadway beneath the goaf is located in a pressure-relief environment. For the identification of the stress basis, a floor stress calculation model is established, and the stress calculation method is corrected, thereby clarifying the necessity of entry retaining by roof cutting under a pressure-relief environment. Meanwhile, a FLAC3D numerical model is established to comparatively analyze the stress and displacement characteristics of the surrounding rock of the roadway under roof-cutting and non-roof-cutting conditions, and the results are verified by an in situ industrial test. The theoretical calculation results indicate that the 8307 auxiliary intake roadway satisfies the two conditions for being located in a stress reduction zone. The numerical simulation results show that, after roof cutting, the vertical stress on the solid coal side decreases by 19.7%, and the maximum vertical displacement decreases by 20.6%. The field statistical results show that the average convergence between the roof and floor after entry retaining is 399 mm, the average convergence of the two ribs is 160 mm, and the average deformation rate of the retained-entry section is 17.44%, which satisfies the reuse requirement. The research results can provide a reference for the design of entry retaining by roof cutting under similar goaf conditions.
Zheng et al. (Wed,) studied this question.