Evaluation of the relative influence of major parameters for laterally loaded piles by three dimensional finite element models.

摘要

Three dimensional finite element models are developed to evaluate the relative influence of major parameters for laterally loaded piles. The models include a layer of nonthickness interface elements between the pile and the soil elements which provide for no force transmitted across the interface upon separation and for frictional stick/skip behavior when the surfaces are in contact. Two perfect plasticity constitutive laws, the Von Mises and the Extended Drucker-Prager, are used to model soils. The Von Mises constitutive law is used to model clay soil subjected to undrained loading and the Extended Drucker-Prager constitutive law is used to describe the behavior of sand soils subjected to drained loading.; The models are observed to capture the essential elements of the laterally loaded pile problem in the field. Hence, the models are thought to provide a reasonable basis for the parametric study of pile response. The major parameters include, the soil strength and stiffness, the nature of interface elements, the unit weight of soil, the initial horizontal stress of soil, load reversal, pilehead fixity, pile spacing (both in a row of piles and in multiple rows of piles), and the degree of slope of the soil near the pile.; The results of analyses are evaluated in terms of the load vs deflection relationships, of bending moment vs pile depth and of soil resistance (p) vs pile displacement (y). The p-y curves are derived from the bending moment vs pile depth relationship in a way similar to that used for physical experiments.; Among the major parameters, the pile spacing is found to have a potentially large effect on the pile response. In the case of the pile group with pile spacing parallel to the lateral loading, the maximum soil resistance in the trailing row of piles may reduce as much as 50%. The P-multiplier was used to quantify the reduction of the soil resistance in the trailing row of piles and recommendations for design are proposed.; On some occasions, piles are imbedded in the sloping ground. The effect of the sloping ground on pile response is examined. It is found that sloping ground has a significant effect on the soil resistance in the down slope direction.