The existing method to design laterally loaded piles in medium stiff clay using p-y curves has been re-examined based on the results from a series of field tests in Shanghai, PRC. An improved method is proposed in this paper for the design of laterally loaded single piles in cohesive soils. The p-y curves have been related to the hyperbolic constitutive relationship of clays derived from triaxial tests. A relationship between the strain f50 at the triaxial tests and the deformation y 50 at the laterally loaded piles has been derived. It is recommended to reduce the shear strength to reflect the actual behaviour of overconsolidated clays.
The design of the piles supporting e.g. drilling and production platforms is often difficult since these structures are mainly subjected to very high lateral loads caused by wave, wind and ice forces. The lateral resistance of the piles is usually calculated using p-y curves. This method is used in many countries for the planing, design and construction of fixed offshore platforms (e.g. API, 1975, 1989). A number of lateral load tests with single piles have been carried out in both cohesive and cohesionless soils where the piles have been subjected to both static and cyclic loading (e.g. Matlock, 1970 and Reese et aI., 1975a). There are also some investigations of laterally loaded pile groups (e.g. Prakash, 1962, Poulos, 1971, and Reese, 1986). The method using p-y curves which initially was proposed by Matlock (1970) and Reese et al. (1975a) is based on the results from field tests. This method is an extension of the method proposed by McClelland and Focht (1956) where a nonlinear p-y relationship in the elastic range is used and of the method to predict the ultimate lateral resistance of soils in the plastic area (Broms, 1964a, 1964b, 1965).