What characterizes general shear failure in soils?

General shear failure in soils is characterized by a sudden and complete loss of shear strength, which typically occurs when the soil reaches its peak strength under increased loading. This type of failure is marked by clear and well-defined failure surfaces, resulting in a rapid and often catastrophic structural failure. As the load increases, the soil will resist deformation until it reaches a critical point, at which it fails suddenly. This behavior is crucial for understanding the stability of foundations and earth structures, as it can lead to significant and rapid failure without much prior warning.

The other options do not accurately represent general shear failure. For instance, gradual failure is more characteristic of other types of shear failures such as direct or punching shear in soils, where the failure might occur progressively rather than suddenly. While general shear failure can occur in both saturated and unsaturated soils, it is not limited specifically to saturated conditions. Additionally, it affects all types of soil, including sandy, silty, and clayey soils, thus making it inaccurate to state that it only impacts clayey soils. Understanding these distinctions is crucial for geotechnical engineering and soil mechanics.