Technical cross-section diagram of a massive rock roof over an underground elliptical cavity. The roof is subjected to a distributed uniform vertical load from above. Illustrate the 'Global Bending Failure' mechanism: show the roof sagging downwards into the cavity, with visible red-highlighted 'tensile fracture zones' at the bottom-center of the span and at the top-corner abutments where the roof meets the cavity wall. Add schematic arrows representing downward pressure and inward-pushing reaction forces at the cavity walls. Mehr sehen