Study on floor large deformation and failure mechanism of water-rich soft rock roadway

This study investigates the failure mechanisms and stability control of water-rich soft rock roadways, focusing on the severe floor heave in the north wing main roadway of Hongqi Coal Mine, China. Field investigations and laboratory tests were conducted to analyze the deformation characteristics and the water-rock interaction of the surrounding mudstone. A numerical model was developed using the FLAC3D software to simulate the failure process under varying water pressures from the underlying aquifer, examining the evolution of displacement and the plastic zone. A mechanical model for the composite floor heave mechanism was established based on Rankine’s earth pressure theory, from which the driving force and ultimate failure depth were derived. A novel zoned bolt-grouting support technology, integrating an inverted arch, grouting rocbolts, and grouting cable bolts, was consequently proposed. Field application and monitoring confirmed the effectiveness of this support system in controlling deformation, with floor heave reduced to 33 mm. The findings offer theoretical guidance and a practical reference for supporting similar water-rich soft rock roadways.