Rock anchors and rock sockets are both utilized in geotechnical engineering to enhance foundation stability, but they serve distinct primary functions with some overlap.
Rock Anchors: These are primarily designed to withstand uplift forces. They consist of steel tendons or bars anchored deep into stable rock formations, providing a tensile resistance that counteracts the upward forces acting on structures like retaining walls, dams, or towers. While they offer some degree of lateral support, their main role is to prevent uplift and overturning.
Rock Sockets: These serve a broader range of purposes:
Vertical Load Resistance: Rock sockets utilize both frictional resistance along the socket walls and end-bearing capacity at the base to support vertical loads from structures. This is especially beneficial in situations where the surface soil layers are weak or unsuitable for bearing large loads.
Lateral Load Resistance: The passive resistance of the rock socket against lateral movement contributes significantly to the overall lateral stability of the structure. This is particularly important in resisting forces from wind, earthquakes, or earth pressures.
Uplift Resistance (with limitations): While rock sockets can resist uplift forces through shaft friction, only 70% of this capacity is typically considered reliable due to the negative Poisson ratio effect. This effect refers to the tendency of the rock to contract laterally under axial tension, potentially reducing the frictional resistance.
In conclusion, rock anchors are primarily designed for uplift resistance, while rock sockets offer a versatile solution for addressing vertical, lateral, and, to a limited extent, uplift forces. By understanding their distinct functions and limitations, engineers can effectively utilize these technologies to create robust and stable foundations for a wide range of structures.