Field loading tests on large-diameter rock-socketed bored piles of Wuhan Greenland Center Tower

Wuhan Greenland Center Tower is 636 m high with the average pressure stress 1500 kPa on the bottom of foundation. The test piles with a diameter of 1200 mm and a length of about 55 m are applied to field full scale tests. Large tonnage load tests and measurements of axial force and deformation are carried out so that the status of load bearing and deformation capacity of socketed piles are obtained, and the test results are valuable to the study of the bearing capacity and load transfer mechanism of large-diameter socketed piles in Wuhan area. The results show that the load-settlement curves of the 4 piles are all mild ones, and their bearing capacities are larger than 45000 kPa. The settlements at engineering pile top are 9.7~10.82 mm, and those at pile tip are 2.35~2.83 mm. Side friction distribution and bearing characters of piles embeded in sand rocks are different from those of mudstone. The tip resistance ratios of the 4 piles are 45.3%~58.7%. The calculation method in China's technical code for building pile foundations underestimates the tip resistance of soft rock and very soft rock.