Field test of a floating thermal pile in sensitive clay
Journal article, 2021

The response of floating pile foundations in deep deposits of soft clay is governed by the settlements within the clay deposit surrounding the piles. A long-duration thermal response test (TRT) has been performed to assess the impact of heating and cooling on the geotechnical performance of a vertically loaded slender tubular steel pile in a deep deposit of sensitive clay. The results from the instrumented test site indicate that negligible excess pore water pressures, up to 3 kPa during heating and down to -1ยท1 kPa during cooling, were generated in the soil adjacent to the pile for a 50 W/m heat flux. The heating rate was sufficiently low to facilitate the drainage of pore water. The influence radius for the excess pore water pressures, however, extended beyond the soil volume affected by temperature change. The absence of thermally triggered creep settlements could be explained by the overlap between the remoulded zone resulting from pile installation, the extent of the heating, and the low creep susceptibility of remoulded sensitive clay for moderate temperature changes. Furthermore, no difference in the ultimate bearing capacity was found between the thermal pile and the reference pile, which was only loaded with a serviceability load during the test series. The current test data, therefore, indicate that driven floating piles in a deep deposit of soft clay also function as heat exchanger piles with minimal detrimental effects, for similar operational conditions as used in the TRT. It should be noted, however, that other pile types that do not extensively remould the clay adjacent to the pile shaft may show more significant influence of the thermal changes.

Full-scale tests

Consolidation

Clays

Temperature effects

Piles & piling

Creep

Settlement

Author

Anders Bergström

NCC AB

Saqib Javed

Lund University

Jelke Dijkstra

Chalmers, Architecture and Civil Engineering, GeoEngineering

Geotechnique

0016-8505 (ISSN)

Vol. 71 4 334-345

Development of modeling and simulation tools for geothermal basements and deep foundations in soft clays

Swedish Energy Agency, 2013-06-15 -- 2015-03-31.

Subject Categories

Energy Engineering

Geotechnical Engineering

Manufacturing, Surface and Joining Technology

DOI

10.1680/jgeot.19.P.094

More information

Latest update

4/27/2021