Abstract
Sandstone-roofed roadways are susceptible to deformation and failure caused by reservoir-water-induced disturbances, thereby compromising human safety. Using rock-mechanics testing techniques, numerical simulations, and engineering principles, this study investigates the strength, deformation, and pore-structure characteristics of sandstone roofs as well as means to support the surrounding rock structure. The results obtained in this study reveal that the residual strain is proportional to the pore-water pressure, which, in turn, causes a significant reduction in the elastic modulus during the unloading phase. Furthermore, an increase in the pore-water pressure causes the shear failure of specimens in compression. The delay between crack initiation and specimen-volume expansion decreases. Moreover, the specimen demonstrates increased deformation and failure responses to changes in the confining pressure, thereby resulting in accelerated conversion. Changes in water inflow can be correlated to crack initiation, propagation, and fracture. This water inflow gradually increases with an increase in the osmotic pressure. Correspondingly, the volumetric strain required for maximum water inflow undergoes a gradual decrease. The increased water inflow can be considered a precursor to specimen failure. In addition, fractures in the surrounding rock structures are mainly caused by joint dislocations. The increase in pore pressure promotes the development of dislocation fractures in the deep surrounding rocks. Subsequently, these fractures overlap with their open counterparts to form large fractures; this increases the roadway-roof subsidence and layer separation of the shallow surrounding rocks, thereby further increasing the fracture count. Lastly, the use of high-performance rock bolts, cable-bolt reinforcements, and W-shaped steel bands is expected to ensure the stability of rocks surrounding sandstone-roofed roadways subject to water-pressure disturbances.
Highlights
Sandstone-roofed roadways are susceptible to deformation and failure caused by reservoir-water-induced disturbances, thereby compromising human safety
Using rock-mechanics testing techniques, numerical simulations, and engineering principles, this study investigates the strength, deformation, and pore-structure characteristics of sandstone roofs as well as means to support the surrounding rock structure. e results obtained in this study reveal that the residual strain is proportional to the pore-water pressure, which, in turn, causes a significant reduction in the elastic modulus during the unloading phase
The volumetric strain required for maximum water inflow undergoes a gradual decrease. e increased water inflow can be considered a precursor to specimen failure
Summary
En, the axial pressure was loaded with a predetermined value set to 70% of the conventional triaxial compressive strength (around 23 MPa). The confining pressure was unloaded at 0.1 MPa/min until the specimen fractured. Combined with the actual site data of the embedded depth of the roadway of around 300 m, a confining pressure of 4.0 MPa was determined. E triaxial compressive strength was obtained as σc 32.5 MPa, which provided the basis for the unloading test; the loading rate during the test was 0.2 MPa/min. (3) Five pore pressure gradients (0, 0.1, 0.2, 0.4, and 0.6 MPa) were applied to the sandstone samples during the triaxial unloading test to simulate the different water pressures resulting from changes in the reservoir water levels at specific embedded depths. (3) Five pore pressure gradients (0, 0.1, 0.2, 0.4, and 0.6 MPa) were applied to the sandstone samples during the triaxial unloading test to simulate the different water pressures resulting from changes in the reservoir water levels at specific embedded depths. e axial and confining pressures were
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
