Compressive Capacity of Conventional and Under Reamed Piles in Soft Clay

Abstract

Abstract Under reamed pile is a well-known solution for carrying roads, light structures, walk sides, communication and electrical tower and rail. In this laboratory study, the compression conduct of conventional pile and undreamed pile with single and double bulbs models with shaft diameter of 10 mm embedded in soft clay soil layer overlaying sand soil was investigated. The sand layer with a depth of 300mm was compacted into six sub layers to relative density 70% in a steel container of a diameter 300mm in size. The depth of soft clay was 250mm and undrained shear strength (Cu) 35 kPa which compacted into five sub layers on sandy soil layer. A series of tests of model are performed on conventional and underreamed pile. Different lengths of piles are manufactured like 250mm, 290mm, 330mm, 370mm and 410mm and with bulb of a diameter 20mm. Moreover, single bulb and dual bulbs were utilized for these piles, a comparison in behaviour between underreamed pile and conventional pile (without bulb) is fulfilled. This study appeared finalize the ultimate compressive capacity of underreamed pile of single bulb is (1.9, 2.6, 3.3, 3.4 and 3.2) times greater than conventional pile while the underreamed of double bulbs is (4.1, 3.7, 4.3, 4.1 and 3.7) times greater than conventional pile for ratios of L/ D (25, 29, 33, 37 and 41) respectively. A proposed relationship used to estimate ultimate compressive capacity for conventional pile and underreamed pile with single and double bulbs when dimensions of pile are known or used to estimate dimensions of pile for specified load capacity.