FROM LABORATORY TO FIELD: QUESTIONING ISOTACH VALIDITY IN PEAT COMPRESSION

Multiple long-term constant rate of strain (CRS) tests were performed on Zegveld peat from the Netherlands. The aim of performing these tests is to check the validity of the classical isotach framework in describing the compression behaviour of peat. Based on parallel equidistant isotachs, the classical isotach framework forms the basis of common settlement prediction models.

The strain rates of different projects built in peat areas are analysed to compare field strain rates with the strain rates applied during conventional CRS laboratory testing. This showed that field strain rates are substantially lower than those applied in conventional CRS testing.

Different isotachs are visualized by changing the applied displacement rate during CRS testing. The trajectories of these isotachs are determined to conclude on both the level of parallelism as well as the mutual distance between different isotachs. From the performed tests it is concluded that the classical isotach framework is inadequate in capturing the compression behaviour of the tested Zegveld peat at low strain rates. This is important since it is concluded that low strain rates best approach field conditions.