장기 반복하중을 받는 모래지반의 축방향 누적소성변형률 평가

Abstract

Offshore wind turbines have been constructed extensively throughout the world. These turbines are subjected to approximately 108horizontal load cycles produced from wind, waves, and current during their lifetimes. Therefore, the accumulated displacement of the foundationunder horizontal cyclic loading has significant effects on the foundation design of a wind turbine. Akili(2006) and Achmus et al.(2009) performedcyclic triaxial tests on dry sands and proposed an empirical model for predicting the accumulated plastic strain of sands under long-term cyclicloading. In this study, cyclic triaxial tests were performed to analyze the cyclic loading behaviors of dry sands. A total of 27 test cases wereperformed by varying three parameters: the relative density of the sands, cyclic load level, and confining stress. The test results showed that theaccumulated plastic strain increased with an increase in the cyclic load level and a decrease in the relative density of the sand. The confining stresshad less effect on the plastic strain. In addition, the plastic strain at the 1st loading cycle was about 57% of the accumulated strain at 1,000 cycles. Finally, the input parameters of the empirical models of Akili(2006) and Achmus et al.(2009) were evaluated by using the relative density of thesand and the cyclic load level.