Discussion of 'A Comparative Study of Suction-Induced Seepage Consolidation Versus Centrifuge Consolidation' by R. G. Robinson, T. S. Tan, and F. H. Lee

摘要

The authors have presented a valuable study with high quality experimental data on the use of seepage to preconsolidate a clay specimen prior to placement in a geotechnical centrifuge for final consolidation. As a result of this technique, considerable centrifuge time is saved in the preparation of normally consolidated clay beds for subsequent centrifuge testing. The authors conclude that the use of water suction on the bottom of the specimen during seepage consolidation is more effective in preventing hydraulic fracturing than the use of high water pressure on top of the clay, even though the two methods produce identical effective stress profiles (Fig. 1). We are curious as to the physical mechanism that is responsible for this effect. One possibility is that high water pressure on top causes expansion of the walls of the strong box, which thereby facilitates channeling of water down the sidewalls. Another possibility is that the propensity for water channeling is related to pore pressure rather than effective stress at the sidewalls. Under conditions of high water pressure on top, the water uses any tiny irregularity in slurry level or density as an access point and then propagates downward due to reduced effective stress at the tip of the channel. Any comments from the authors on this issue would be welcome.