LATERAL LOAD CAPACITY OF ROCK SOCKETED PIERS

Abstract

Often the foundations of heavy structures like multi-storeyed buildings, bridges and dams are placed on rock mass. Rock masses in nature contain numerous discontinuities as cracks, joints, cleavages, beddings and/ or even faults. Deformation and failure of rock mass are greatly dependent on the presence of such geological discontinuities. For this reason, greater degree of conservation is exercised in the estimation of load carrying capacity and resulting deformation of rock mass. Foundations are designed to be safe against these essential requirements. Generally, the bearing capacity of rocks is higher than that of soils. The compressive strength of an intact rock could vary from 1 MPa to more than 200 MPa (Ramamurthy, 2007). Due to presence of defects in the rock mass, compressive strength and modulus are considerably lower. At shallow depth where stresses are low, the failure of the intact rock material is minimal, and the behaviour of the rock mass is controlled by sliding along the discontinuities (Hoek, 2000). The compressive loads from the structures whether vertical, inclined or horizontal will have to be transmitted to the rock mass through individual spread footing, strip, mat, caisson or pile shaft and its tip. Rock sockets are provided as foundation of bridge piers and estimation of lateral load capacity of rock sockets is a challenging task till date. In present dissertation an attempt has been made in this direction