HPMC viscous fluid for centrifuge modelling

Abstract

Dynamic pile installation is a challenging aspect of the realization of offshore infrastructure. Due to the large-scale and specialized hardware involved, researchers have resorted to centrifuge modelling to study this process at a manageable scale and in a controlled environment. However, in centrifuge models, a discrepancy between the dynamic and diffusive timescales is introduced. By using a viscous fluid, the discrepancy is mitigated, thereby synchronizing both timescales. Hydroxypropylmethylcellulose (HPMC) is a versatile and affordable thickening agent, widely used in centrifuge modelling of dynamic processes. However, the rheological behavior of HPMC solutions can vary based on the type of HPMC and the solution concentration. This study investigates how the rheological behavior of HPMC solutions is influenced by the concentration and the type of HPMC. We present a detailed preparation protocol for preparing aqueous HPMC solutions and propose a generic powerlaw function that unifies experimental results from our study and those of previous works. We investigate the implications of varying degrees of shear thinning, as observed across different HPMC products, by examining the pore pressure response during the dynamic installation of a pile in dense sand saturated with fluids of similar dynamic viscosity. Our findings support the use of viscous fluids for studying dynamic events in the centrifuge but also emphasize the importance of selecting a viscous fluid whose rheology does not vary considerably within the range of expected shear rates. In broader terms, this work streamlines the manufacturing of viscous fluids for use in the centrifuge and advances research efforts related to modelling dynamic phenomena in geotechnical engineering.