Which of the following is most prone to slope failure?

Correct option is B

1. Dipping Fractured Limestone on a Clay Bed:
· Fractured limestone is inherently weak due to the fractures, and when it rests on a slippery clay bed, the entire unit becomes unstable.
· Clay has low shear strength, and the dipping orientation creates a favorable plane for sliding, especially when saturated with water.
2. Other Options:
· (a) Conglomerate:
· Typically consists of well-cemented coarse-grained material, making it relatively stable. It is less prone to slope failure unless highly weathered.
· (c) Horizontally Bedded Quartz Sandstone:
· Horizontal bedding provides structural stability as there are no inclined planes for sliding.
· (d) Basalt Dike:
· Basalt is a dense and strong igneous rock. While dikes may weather over time, they are less prone to slope failure compared to fractured or layered rocks.
3. Factors Leading to Slope Failure in (b):
· Fractures: Create planes of weakness in the limestone.
· Clay Bed: Becomes slippery when wet, reducing friction.
· Dipping Orientation: Promotes downhill sliding along the inclined surface.
Thus, the combination of fractured limestone, a clay base, and dipping orientation makes (b) the most prone to slope failure.
Information Booster: 1. Slope Failure Factors:
· Weak materials (e.g., clay or fractured rock).
· Water saturation reducing shear strength.
· Steep slopes or dipping layers.
2. Common Slope Failure Types:
· Rotational slides, translational slides, and debris flows.
3. Prevention:
· Proper drainage to reduce water content.
· Reinforcement of slopes with retaining structures.
· Avoiding construction on inherently weak geological formations.