Cyclic p-y curves of monopiles in dense dry sand using centrifuge model tests

Abstract

In this study, centrifuge model tests were used to examine the lateral behavior of a monopile embedded in dry sand through cyclic lateral loading tests. The soil specimens used in the tests were dry Jumunjin sand with a relative density of 80% and a friction angle of 38°. A static loading test was performed once, and cyclic loading tests were performed four times using four magnitudes of cyclic load (30%, 50%, 80%, and 120% of static lateral capacity). The experimental cyclic p-y curve was obtained through the tests, and the maximum soil resistance points that were found for each load were used to find the cyclic p-y backbone curve for each depth. The two variables which are needed to define the cyclic p-y backbone curve, i.e., the initial modulus of subgrade reaction (kini) and ultimate soil resistance (pu), were suggested as functions of the soil's physical properties and the pile. The cyclic p-y curve of the first cycle and the 100th cycle were formulated to present the upper limit and lower limit. The suggested cyclic p-y curve had an overestimated soil resistance compared with the existing API (1987) method, but the initial modulus of subgrade reaction was underestimated.