Triaxial response of clays reinforced with granular columns

Abstract

The response of soft clays that are reinforced with granular columns is expected to be affected by the rate of loading and drainage conditions. The objective of this paper is to bracket the range of loading conditions in the field by analysing the results from 114 drained and undrained triaxial tests that were compiled in a state-of-the-knowledge database. For a given reinforcement condition, the percentage improvement in load-carrying capacity was found to be higher for undrained conditions than for drained conditions. The variation in the magnitude of the percentage improvement in strength with area replacement ratio indicated that, for drained conditions, there could be an upper bound area replacement ratio beyond which the benefits of increasing the area ratio become economically unjustifiable. The database was also utilised to test the validity of the concept of the critical column length. For both drained and undrained tests, results showed clear evidence that the rate of the percentage improvement in strength decreases significantly as the ratio of the column height to diameter increases beyond values of 5·0–6·0 for undrained tests and 7·0–10·0 for drained tests.