In the context of slope stability analysis using the method of slices, what geometric shape is typically assumed for the critical slip surface in homogeneous cohesive soils?

In the context of slope stability analysis using the method of slices, the geometric shape typically assumed for the critical slip surface in homogeneous cohesive soils is a circular arc. A critical slip surface is the potential failure plane within a soil mass that produces the lowest factor of safety, signifying the most probable path of failure. Homogeneous cohesive soils are characterized by uniform engineering properties, such as shear strength, throughout their mass and possess significant internal bonding, known as cohesion; examples include uniform clay deposits. The method of slices is a limit equilibrium technique that discretizes the soil mass above a potential slip surface into vertical slices to calculate the forces or moments acting on them, allowing for the determination of slope stability. The assumption of a circular arc is highly appropriate for these soils because their relatively uniform cohesive strength often leads to rotational slides, where a block of soil rotates along a curved path. This circular geometry effectively models the path of least resistance for such rotational failure mechanisms in conditions where cohesive strength predominates.