When excavating, which factor is crucial when determining slope stability?

Soil type is a crucial factor in determining slope stability during excavation because different types of soil have varying physical and mechanical properties, such as cohesiveness, density, and angle of internal friction. These properties directly influence how well the soil can support itself and resist collapse when excavated. For example, clay soils may have high cohesion and support steep slopes, while sandy soils may be less stable and require flatter slopes to avoid failure. Understanding the soil type allows engineers and excavation teams to assess the risks associated with excavation activities and implement appropriate safety measures, such as selecting the right slope angle or using reinforcement systems to ensure stability.