Which protective system is designed to prevent cave-ins during excavation work?

The protective system specifically designed to prevent cave-ins during excavation work is trench boxes. These structures are utilized in excavations to support the walls and prevent soil from collapsing, ensuring the safety of workers inside the trench. Trench boxes provide a rigid framework that holds the soil back, allowing workers to safely operate below ground level.

In contrast, scaffolding is used to provide support and a safe working platform above ground, primarily for tasks such as painting or construction at height, and does not address subsurface safety. Netting serves to catch falling debris but does not prevent cave-ins in excavations. Basic shoveling, while a fundamental excavation task, does nothing to enhance worker safety against potential cave-ins. Therefore, trench boxes are the appropriate choice for preventing cave-ins during excavation work.