Small-Scale Testing of Laterally Loaded Non-Slender Monopiles in Sand

In current design of offshore wind turbines, monopiles are often used as foundation. The behaviour of the monopiles when subjected to lateral loading has not been fully investigated, e.g. the diameter effect on the soil response. In this paper the behaviour of two non-slender aluminium piles in sand subjected to lateral loading are analysed by means of small-scale laboratory tests. The six quasi-static tests are conducted on piles with diameters of 40 mm and 100 mm and a slenderness ratio, L/D, of 5. In order to minimise scale effects, the tests are carried out in a pressure tank at stress levels of 0 kPa, 50 kPa, and 100 kPa, respectively. From the tests load-deflection relationships of the piles at three levels above the soil surface are obtained. The load-deflection relationships reveal that the uncertainties of the results for the pile with diameter of 40~mm are large due to the small soil volume activated during failure. From the load-deflection relationships normalised as H/(L2D') and y/D indicates that the lateral load, $H$, is proportional to the embedded length square times the pile diameter, L2D. Furthermore, by comparing the normalised load-deflection relationships for different stress levels it is seen that small-scale tests with overburden pressure applied is preferable.