Estimating in situ compression parameters from remoulded and field test data

Richard Kelly


Conventional sampling and testing procedures cause disturbance of soft clays during sampling, transport and testing resulting in inaccurate measurement of in situ compression parameters. A pilot study has been performed to assess the feasibility of a method for estimating in situ parameters from the results of routine laboratory tests on remoulded soil and in-situ measurements of sensitivity. The computed parameters are compared with data back-analysed from embankments that settled more than anticipated. The results of the study were in reasonable agreement with the back analysed values and were greater than design values adopted from the results of conventional laboratory tests. Piezocone data can be used to develop a continuous profile of coefficients of compression with depth once a profile of plasticity index with depth for the soil is known. Further work is required to increase confidence in the method.