Failure control method based on large deformation full path of GSED with thick, soft roof: Source limitation, path blocking, and environmental reinforcement

• Three thick, soft roof failure modes in roadway driving/maintenance are identified, with their failure evolution clarified. • The failure control of “stress source control - transmission path blocking - acting environment reinforcement” is proposed. • Cut off the hanging roof of the pillar side, improve the rock structure, block stress transfer, and strengthen the support. • Two-way controlled blasting for roof-cutting and bolt-cable-metal mesh-steel beam support for reinforcement were adopted. Gob-side entry driving (GSED) is widely used in China’s mines for its high recovery rate. Herein, the geological characteristics and parameters of the roof are critical to gob-side entries (GSE). The thick and soft immediate roof (TSIR) often deteriorates significantly under multi-round mining-induced stress, causing failure in controlling GSE and stope surrounding rock. When TSIR exceeds three times the mining height and bolt length, GSED projects are directly impacted. Field geological surveys and comprehensive borehole detection identified three TSIR failure types with varying degrees during roadway excavation and maintenance, and their failure evolution mechanisms were clarified. Based on the “source control-path blocking-environment reinforcement” concept, a dual pre-control method is proposed: roof-cutting for pressure relief and reinforcement for roadway protection. It severs the end-hanging roof of the key masonry beam on the coal pillar rib to improve surrounding rock structure, blocks mining-induced stress transmission, and reinforces GSE support simultaneously. Refined theoretical calculations and simulation comparisons verified the dual-control parameters: roof-cutting depth (over 6.2 m, penetrating the entire TSIR), 5° angle, and an 8-m narrow coal pillar (enhancing bearing capacity and limiting rib bulging). Simulations showed that under these parameters, ground pressure behavior of the coal pillar ahead of the GSED face was lower than that of solid coal, with the solid coal stress increase coefficient controlled within 1.6. Bidirectional cumulative energy-controlled blasting was employed for roof-cutting and pressure relief, with bolt-cable-metal mesh-steel beam combined support for roof reinforcement. Field observations revealed clear bidirectional crack propagation in boreholes post-roof-cutting, with effective control of GSE and stope surrounding rock. This research provides practical, effective control strategies for GSED support failure under TSIR deterioration.