Summary
The paper outlines some engineering aspects of tills, particularly at Milton Keynes, and demonstrates methods for their investigation. The methods discussed include the display in vertical section of geotechnical index parameters determined for samples taken from a trench, shallow geophysical techniques and large scale in situ testing. These are all seen as complementary to a preliminary geological investigation.
The objects of this specific study were twofold: to establish the variability of engineering properties with its consequent effect on representability of results and necessary sampling interval, and to investigate the presence of depositional features detrimental to engineering operations in tills, particularly at the Milton Keynes site. The variability was found to be so great that borehole methods were not applicable. A pre-existing shear plane extending from ground surface to about 3.5 m depth was also discovered. These considerations prompted the recommendation of special investigation procedures to suit the circumstances.
