The effect of a soft layer on the cone resistance of a sand layer has been studied extensively, but the same cannot be said for the case of multi-layered deposits with many (thin) alternating soil layers. For geotechnical analyses based on cone penetration test data it is difficult to estimate a representative value of the cone resistance when encountering alternating thin layers of clay or peat and sand. This paper presents physical modelling tests to understand the ‘value’ of the cone resistance in thinly multi-layered soil deposits. The test results are compared with existing analytical methods. It is concluded that the characteristic resistance of the individual layers, the layer thicknesses relative to the cone diameter and the number of layers within the zone of influence of the cone affect the cone resistance in deposits containing multiple thin soil layers. Suggestions for practical implementation are also given.

This paper presents the results of an experimental 1 and numerical investigation on the collapse of dykes involv-2 ing soft soils. Nine centrifuge tests were carried out to in-3 vestigate the dyke-subsoil interaction. The tests consisted in 4 placing a dyke made out of Speswhite clay or Baskarp sand 5 on a subsoil. The dykes and the subsoils were alternatively 6 changed to explore the different contrast in stiffness ranging 7 from stiff dykes on soft subsoil to soft dykes on stiff sub-8 soils. The small scale models were placed in the centrifuge 9 and were progressively accelerated up to a maximum of 100 10 G. The video recordings, which were then processed by Par-11 ticle Image Velocimetry (PIV), offered an insight onto the 12 deformation and failure mechanisms. The results showed 13 that dykes placed on a stiff subsoil underwent brittle fail-14 ures with the development of slip surfaces whereas the same 15 dyke placed on a soft subsoil underwent large deformation 16

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