Research on High Strength and Pre-stressed Coupling Support Technology in Deep Extremely Soft Rock Roadway

The roof and floor of transportation roadway of S₂S₂ working face of Xiaokang coal mine were oil shale and siltstone. The content of clay mineral in the surrounding rock was about 60–80%, which was easy to softening with water and weathering. The deformation of primary archy support roadway was serious and the repair rate was high. To control effectively the deformation of extremely soft rock roadway of Xiaokang coal mine, A combined support system of circular full closed section + high strength and pre-stress anchor + “W” strip + powerful anchor cable + shotcrete + 360U yieldable steel support + back wall filling support was suggested. By combining numerical calculation and field measurement, the convergence and convergence velocity of new circular support roadway were analyzed after excavating completion and compared with the value of primary archy support roadway. The convergence and convergence velocity of new circular support roadway significantly decreased. The deformation of surrounding rock tended to be convergent in a relatively short time. The new supporting technology was a kind of effective control method for the large deformation roadway of deep extremely soft rock. The experience for reference was provided for the support of roadway of other similar mine.