Enhancing the Lateral Behavior of Piled Rafts Over Soft Clay by Strengthening the Soil and Enlarging the Pile Diameter

This paper aims to evaluate the potential enhancement of the lateral capacity of piled rafts in soft clay by adopting one or both of the following scenarios: (1) soft clay improvement by either jet grouting or soil replacement and (2) enlarging the pile diameter. Three-dimensional finite element analyses were carried out on a validated model in which a piled raft was constructed on a deep layer of soft clay underlain by sand. The study mainly investigated the impact of varying the depth, width, and location of the improved clay with or without increasing the pile diameter. A detailed comparison was carried out between the outcomes of the present study, and the mechanism of improving the lateral capacity was discussed. The study reveals that grouting the clay obtains the highest level of improvement in the lateral resistance of piled rafts compared to the other soil improvement methods. No worthy increase in the lateral resistance was observed when the depth of replacement sand was less than twice the pile diameter (2D(p)). If the clay was enhanced beside the raft only, the lateral resistance was enhanced by increasing the enhanced depth to 6D(p), beyond which there was no further rise in the lateral resistance. Enlarging the pile diameter up to 1.0 m is effective if the required load improvement ratio (IR) is not more than 1.27, beyond which a soil improvement technique is a must to achieve a higher IR.