Combinations of In Situ Tests for Control of Ground Modification in Silts and Sands

This paper investigates the use of in situ test data to characterize the changes in stress and density induced by ground improvement. Testing comprised seismic cone penetration tests, full displacement pressuremeter tests and resistivity cone penetration tests. After ground treatment, changes were observed in tip resistance, pore pressure response, shear wave velocity, the characteristics of pressuremeter curves and bulk resistivity. Some of these changes can be caused by changes in lateral stress as well as by density increases. The results generally indicate that the use of a combination of in situ tests will improve our understanding of the changes in soil behaviour achieved by ground treatment. The improved understanding of soil behaviour obtained from combinations of tests may allow ground improvement specifications to be written in terms of a desired post-treatment stress-deformation response. However, further research is required to develop reliable methods of characterization of stress-deformation behaviour.