Experimental Investigation of Eccentrically Loaded Piled Raft Resting on Soft Cohesive Soil

Abstract

Piled rafts have been used successfully in a wide variety of geotechnical applications. However, behaviour of piled raft placed in cohesive soil is not extensively studied. The present research paper describes the performance of eccentrically loaded square rafts connected to short piles and resting on soft cohesive soil. The load was applied with varying eccentricity (e) to raft width (B) ratios of 0.05, 0.1 and 0.2. Experiments were conducted with two different raft sizes of 180 mm × 180 mm and 220 mm × 220 mm connected to 0, 2, 3, 4 and 5 numbers of piles in different cases. The results showed that in general as compared to unpiled rafts, the average bearing pressure increased almost two times for piled rafts having 5 piles corresponding to e/B = 0.2. For rafts with 5 numbers of piles the average settlement reduced to almost one-third in most cases as compared to rafts without pile corresponding to identical e/B ratio. The foundations were also proved to be greatly effective in reducing the tilt. For e/B = 0.05, on increasing the number of connected piles from 0 to 5, the tilt reduced from 2.00° to 0.19° in case of 180 mm × 180 mm raft, and from 2.15° to 0.10° corresponding to 220 mm × 220 mm raft respectively.