Field tests of rock-socketed monopile in coastal area subjected to lateral cyclic loading

Field tests were carried out to study the lateral cyclic loading characteristics of rock-socketed monopile in coastal area, and the variation law of pile body accumulative displacement, unloading stiffness, and pile body bending moment with the cyclic number and cyclic loading amplitude were obtained by actual measurement. Test results show that the cyclic loading history with sa small amplitude has a certain effect on the cyclic accumulative displacement and the degradation of unloading stiffness, and both the peak bending moment and locking moment of the pile body increase with the increase of cyclic numbers. By using the normalization method and formula fitting method, it is found that, the accumulative rate of cyclic displacement, the degradation rate of unloading stiffness, and the variation rate of peak bending moment of single piles in weathered rock layers are significantly smaller than those of sand foundation or clay foundation. The cyclic p-y curves at different depths are derived, and the different hysteretic characteristics between shallow cyclic p-y curve and deep cyclic p-y curve are explored. Finally, the static load test after cyclic tests was carried out, and it was found that the lateral bearing performance of the rock-socketed monopile was greatly degraded after a total of 3000 times of lateral cyclic loading.

Automated summary

Field tests were conducted to investigate the behavior of rock-socketed monopile under lateral cyclic loading in coastal areas. The studies measured the displacement, stiffness, and bending moment of the pile under different cyclic loading conditions. The test results showed that small amplitude cyclic loading had an impact on the displacement and stiffness degradation, while the bending moment increased with the number of cycles. Moreover, the rate of displacement accumulation, stiffness degradation, and bending moment variation were found to be smaller in weathered rock layers compared to sand or clay foundations. Furthermore, the hysteresis behavior of shallow and deep cyclic p-y curves was explored. Finally, the lateral bearing performance of the rock-socketed monopile was found to degrade significantly after 3000 cycles of lateral cyclic loading through static load tests.