Bearing capacity of monotonically installed tapered piles in medium-dense Fontainebleau sand

Tapered piles installation in medium-dense Fontainebleau sand and subsequent loading were performed in the geotechnical centrifuge at Gustave Eiffel University. The physical setup includes models of piles with three different shapes – straight profile (S) and two conical with taper angles of 0.70 degrees (T1) and 1.4 degrees (T2). The aim of the study was to identify the optimal pile shape with respect to installation and load-bearing capacity. After the monotonic installation, the penetration depth and volume were the same for all pile models. Afterwards, the models were subjected to static load tests in compression and then in tension. A considerable increase in shaft friction during tapered piles installation was observed. The maximum average shaft resistance was about six and eight times higher for the T1 and T2 models, respectively as compared with the S pile. The shaft friction in compression was higher for tapered models than for cylindrical ones. Larger peak values of shaft friction in tension were also noticed for tapered piles. Similar shaft friction in tension and compression was found for cylindrical pile. On the contrary, the shaft friction ratio of tension to compression is about 0.33 and 0.14 for T1 and T2 piles, respectively.