Full-scale embankment failure test under simulated train loading

Abstract

A full-scale embankment failure experiment was conducted in 2009 in Perniö, Finland. A small, extensively instrumented railway embankment on a soft clay foundation was brought to failure by loading over a period of 30 h. Instrumentation consisted of over 300 different measurement points, including 37 piezometers and nine automatically monitored inclinometer tubes. The relatively rapid loading simulated a heavy train coming to a standstill on the embankment. The primary purpose of the experiment was to gather field data of a failure caused by a rapidly applied load, with an emphasis on the pore pressure response in the clay foundation layer. The test was also used to assess the suitability of various instruments for real-time stability monitoring. The embankment failure was an asymmetric bearing capacity mechanism that is hypothesised to have been triggered by an undrained creep rupture. During the last 2 h of the experiment, pore pressure and displacements increased at an accelerating rate while the external load was kept constant. The time-dependency of the pore pressure and displacement responses was a key factor in the experiment. With regards to monitoring of similar in-service train embankments, proper placement of instruments according to predicted failure mechanisms was found to be important.