A Substitute Pore Fluid for Seismic Centrifuge Modeling

In seismic centrifuge modeling, a time-scaling conflict exists between dynamic and dissipative phenomena. To help alleviate this fundamental problem, a substitute pore fluid consisting of powdered methylcellulose (known commercially as Metolose) dissolved in water was studied. The methylcellulose-water mixtures are referred to as "metolose" in general from here on. To examine the suitability of this substitute pore fluid, an experimental program was conducted using water- and metolose-saturated sand specimens. The program included triaxial compression tests, permeability tests, and a seismic centrifuge experiment on level ground models. In addition, modeling of models type experiments were conducted on metolose-saturated embankment and retaining wall models. Results from the triaxial tests indicated that the constitutive behavior of the saturated sand specimens was not significantly altered with metolose as the pore fluid. Results from the permeability tests showed that the scaling requirements of the centrifuge environment were satisfied. The centrifuge experiments demonstrated clearly that the conflict between the dynamic and consolidation time scales exists and reinforced the need for a substitute pore fluid in tests designed to model prototype behavior. Based on this experimental program, metolose was found to be an acceptable substitute pore fluid.