4SEED H B, REESE L C. The action of soft clay along friction piles[J]. Proceedings of the American Society of Civil Engineers, ASCE, 1955(81): 112 - 118.
5WONG K S, THE C I. Negative skin friction on piles in layered deposits[J]. Journal of Geotechnical Engineering, ASCE, 1995, 121(6): 457 - 465.
6RANDOLPH M F, WORTH C E Analysis of deformation of vertically loaded piles[J]. Journal of Soil Mechanics and Foundations Division, ASCE, 1978(12): 56 - 61.