Engineering Geology of Glaciated Soils

A research project in being carried out to assess geotechnical soil property anisotropy and principal stress axis rotation in glaciated clays and tills. A glacial process model is proposed which assumes that shearing is the principal means by which these soils obtain their present geotechnical properties. One main outcome of this model is that the assumption of crossanisotropy is not valid for soils affected by glacial action. Review of the literature yields several examples where anisotropic horizontal stresses are measured in glaciated clays.

To verify the proposed model, a series of field and laboratory tests at three sites is proposed. Field testing with a load cell pressuremeter (LCPM) is proposed to measure the possibly anisotropic horizontal stress distribution due to the glacially induced anisotropy. Laboratory testing with a new oedometer designed to measure lateral stress response to axial loading will be used to measure anisotropy of stiffness. Finite element modelling will then be used to link the inferred glacial loading conditions with the measured soil properties as an additional confirmation of the validity of the model.

Preliminary testing in the lateral stress oedometer indicates that horizontal reactions to vertically applied loads are anisotropic in the Pot Clay from the north Netherlands. Further, the orientation (azimuth) of higher horizontal stresses corresponds consistently with the inferred directions of ice advance during the Saalian glaciation.

Additional testing is being carried out to measure horizontal stress anisotropy (in-situ) and the orientation of the principal stiffnesses (in the laboratory).

• Overview

• Problem Definition

• Work Program

• Preliminary Results

• Discussion

• Summary and Conclusions

• References