Mechanism and control strategies of asymmetric floor heave under dynamic pressure in roof-cutting gob-side entry retaining: a case study

Abstract

Abstract Roof cutting for gob-side entry retaining actively modifies the structural configuration of the roof and the two ribs, which intensifies the inherent asymmetry in both the surrounding rock structure and the stress distribution. This structural evolution makes asymmetric floor heave under dynamic pressure a critical challenge. In this study, the mechanisms and control strategies for asymmetric floor heave in roadways under dynamic pressure were investigated through physical model tests, theoretical analysis, and field measurements, followed by a successful engineering application at the Zhaogu No. 1 Mine. Physical model tests verified the advantages of roof cutting in controlling surrounding rock deformation and revealed the evolutionary process of tensile strain in the roadway floor from shallow to deep strata. A mechanical model of asymmetric floor failure under mining-induced dynamic pressure in roof-cutting gob-side entry retaining was established, and the failure depth and plastic zone width after roof cutting were derived using Rankine’s earth pressure theory. Furthermore, a pressure-equalizing support scheme was proposed, incorporating roof pre-splitting, constant resistance & large-deformation (CRLD) support for the roof and coal ribs, and inverted floor beam support for the floor. Field results demonstrated that, compared to the unrestricted floor control scheme, this pressure-equalizing support scheme reduced floor heave by 46.1%. The effectiveness and feasibility of the proposed integrated control scheme were systematically verified through theoretical analysis, physical similarity simulation, and field validation.