DISCRETE ELEMENT ANALYSIS ON ROCK WEDGE FAILURE CONSIDERING TENSILE-SHEAR COMPOSITE FAILURE OF ROCK BRIDGES

This study investigates the mechanism of rock wedge failure by considering the tensile-shear composite failure of rock bridges through three-dimensional discrete element model (3D-DEM) simulations. The DEM model was verified using uniaxial compression, Brazilian indirect tension, and central crack Brazilian disk tests. Subsequently, the tensile strength and failure patterns of the DEM rock models with multiple existing fractures under different distributions were examined. Finally, an actual case of rock wedge failure was studied, and possible wedge failure areas were identified. According to the results, the following conclusions can be drawn: (1) The DEM model can accurately simulate laboratory tests in terms of compressive and tensile strength and their failure modes. (2) The tensile strength of the rock bridge at various rock bridge angles exhibited a U-shaped curve that was significantly affected by the rock bridge angle, spacing, and continuity. (3) The actual slope analysis shows that the tensile strength required to resist wedge failure at different rock bridge angles exhibits an inverted U-shaped curve. The upper part of the inverted U-curve was defined as a safety zone, whereas the lower part was defined as a failure zone. For low rock bridge angles ranging from −20° to 20°, rock wedge failure is prone to occur. (4) Possible wedge failure areas along an expressway were identified. Ultimately, the field investigation results agreed with the slope analysis