In 1985, a section of a New Hampshire roadway located over a deposit of peaty organic soil 20 ft (6 m) thick was widened and raised. On the basis of vane shear strengths, the required embankment height increase of 5 ft was implemented in three stages over a 6-month period. Two years after the initial loading, more than 6.5 ft (2 m) of vertical displacement was observed. This paper presents the results of various in situ tests conducted following these events in material located away from and below the road embankment. The tests included plate load tests, self-boring and full-displacement pressuremeter tests, standard penetration tests, field vane tests, and dilatometer tests. Assessment of the effectiveness of these tests in evaluating useful geotechnical soil parameters for embankment design over very soft peaty organic soils is discussed.
Samenvatting