Settlement predictions of embankments on organic soilsin engineering practice

摘要

Analysis of both laboratory and field measurements on Dutch organic soils are presented usingtwo isotache type settlement models. The a,b,c model based largely on the work of Den Haan (1994) usinga natural strain formulation and a Bjerrum model mainly based on the work of Bjerrum (1967, 1973) andYin and Graham (1989-2002) with both "linear strain" and "void ratio as state parameter" formulations, arecompared. The theoretical background of both models and the main differences are briefly discussed, followedby a parameter determination from laboratory data and back analysis of parameters and reliability determina-tion using field measurements. Application of these models during embankment construction is discussed forseveral projects. These embankments are typically built using a staged construction method with applicationof vertical drains for increasing the rate of consolidation, and preloading for reduction of the post-constructionresidual settlements. The back calculated values for consolidation and compressibility parameters clearly indi-cate that good approximations can be obtained while using the observational method in combination with arelatively simple consolidation and compressibility model. Finally, various recommendations are presented forthe improvement of the predictability of consolidation and settlement behaviour of embankments in engineer-ing practice, after discussing various aspects like sample disturbance, finite strain consolidation and residualsecondary compression after preloading.