BEHAVIOUR OF PILE GROUPS UNDER ECCENTRIC VERTICAL LOADS IN CLAY

Abstract

The piles are used as foundations to transmit loads from the super-structure through soil of low bearing capacity or water to a lower stratum of adequate bearing capacity. The pil(-s are usually driven in groups. The pile groups may be subjected to eccentric vertical loads which may be due to dead and live load of super-structure as in bri 'ges, wharves , heavy industrial buildings and retaining walls. The safety of stru-cture depends upon the ability of the supoorting piles tc tr.an-smit these loa-'s to the strata of adequate bearing capacity, An cxperimenta 1 investigation was carried out on 9 mm outer diameter an('. 5.9 mm inner diameter aluminium pipe piles in a hcmngenccus clay deposit to study the beh~vicur cf pile groups under eccentric vertical loads. The tests were perfcr-med using riles with emkecier. 1^ngths of 30 times the diameter cf pile cn single piles, 2 and 3' groups as free standing = n•' pile,). foundations. The spacing of oilEs in a group was kept as 3 -times the pile diameter... This was kept constant throughout the investigaii~n. Two different c' nsis ienci s of clay one soft and the other medium were us c1. Tes cs were carried out in woo: en boxes in wzich t-nc soil was deposite and the groups were _-driven along with a single piles.. The measurements of vertical displacement, h,)ri- z ntal displacement and rotation were taken under each incre-ment of load. The single piles and pile groups were tFs te ? ,upt failure. Also some- semi spatial tests were carrier' out to study the point of rotation under eccentric load's'.