Which of the following contributes to reduced shear strength in a potentially unstable slope?

The choice related to the disturbance of sensitive materials is significant in understanding slope stability because sensitive materials, such as clays, can lose their shear strength when disturbed. When these materials are disturbed, often through human activities such as construction or natural processes like heavy rainfall or earthquakes, they may become more susceptible to failure.

Disturbance can lead to changes in moisture content or structure, which can dramatically decrease the material’s cohesion and frictional properties, essential for maintaining slope stability. This loss of effective stress in sensitive materials is critical, particularly in areas where fine-grained soils are present, as they can transition from a stable to an unstable condition with relatively little provocation.

In contrast, the other options relate to factors that can influence slope stability differently. Removal of underlying support refers to the undermining of a slope, which can create a direct cause for instability. Surcharging involves adding weight to the top of a slope, which increases the driving forces acting against the resisting forces. Lateral pressure pertains to forces acting parallel to the slope face that may cause sliding or lateral movement. While each of these factors can contribute to slope failure, the disturbance of sensitive materials specifically address a critical mechanism that directly alters shear strength.