Design of Piles for Lateral Loads

Definition of p and y. (After Reese, L.C., Behavior of piles and pile groups under lateral load. A manual prepared for the U.S. Department of Transportation. Federal Highway Administration. Office of Research. Washington, DC, 1983. Reprinted with permission of ASCE.) 

S is the slope of the elastic curve defined by the axis of the pile 

Soil resistance is a non-linear function of pile deflection and depth below the ground surface. The soil resistance can be expressed as follows  

A detailed discussion of the limitations, advantages, and practical experiences has been presented by Sullivan et al. (1979) and Reese and Wang (1986). Results using the p-y method indicate that the lateral loads at mud-line affect only the upper pile length of 10-15 diameters. The magnitudes of the computed bending moments in the pile are relatively insensitive to variations in the assumed p-y curves along the pile, but the lateral displacements and rotations are clearly affected. 

A pile in a group deflects much more than the same pile isolated when subjected to the same lateral load (Cooke et al., 1979 Matlock et al., 1980). The analysis of pile group behavior is by means of an incremental superposition of the nonlinear single-pile behavior based on a p-y analysis and the interaction from the other piles in the group based on an elastic continuum analysis (Poulos, 1981a). 

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