Abstract: The plastic tube pile applied to soft ground treatment of highway, is comprised of pre-driven plastic tube filled with concrete. According to the steel stress gauges embedded in plastic tube pile, the load transfer mechanism of plastic tube pile under embankment load is completely measured during the periods of construction and precompression. And the modified method of steel stress gauge is proposed. The test results show that under the static load of single pile, the axial load of plastic tube pile decreases with the depth increasing, and there is no negative skin friction; under the embankment load, the axial load of plastic tube pile increases first and then decreases, and the distribution of negative skin friction is in the upper 3/5 of pile length; with the increasing of embankment load, the negative and positive skin frictions are gradually increased; however, the location of neutral point of negative skin friction stay the same during the observation period.

Key words: plastic tube pile, pile supported embankment, mechanical behavior, load transfer, negative skin friction