Settlement below embankments: factors controlling the depth of the deformation zone

The issue of settlement and the calculation of the thickness of the deformation zone are addressed in this paper. A short overview is given concerning the thickness of the deformation zone values used in general practice; the available soil models are also briefly introduced. A particular problem is used to compare the results of obtained depth of the influence zone calculated by available formulae and estimated by finite element analyses with different soil models, such as the “hardening soil”, the “Cam-Clay” and the “hardening soil with small strain” models. The deformation zone of a soft clay layer beneath a 10 m-high and 80 m-wide embankment is evaluated, and the results are compared. Special attention is given to the soil models and their capabilities and drawbacks for calculation of deformations due to large embankments

Correlation of undrained shear strength and CPT resistance

The correlation of CPT resistance and undrained shear strength of soft Holocene clays is discussed in this paper. This soil type, covering significant part of Hungary is frequently involved in different geotechnical engineering problems such as building of highway embankments. Soil samples of eight different sites have been studied, samples were taken at each site and cone penetration tests were performed. The samples were tested by means of unconfined compression and consolidatedundrained triaxial compression tests. The correlation of the determined undrained shear strength and the experienced CPT results was evaluated and the empirical cone factors (Nk, Nkt , Nke, NΔu) were determined for each tests. The back-calculated cone factors have been compared with the values suggested by earlier works in this field. The possible correlations between cone factors and different soil properties (such as index of plasticity, pore pressure coefficient etc.) are also discussed in the paper and recommendations are given for estimation of undrained shear strength of Holocene clays