Correlation between the slump parameters and rheological parameters of debris-flow

Abstract

Rheological characteristics are important information for understanding or simulating debris-flow movement. Debris-flow movements involves complex and heterogeneous material with grain size distributions ranging from silt to large rocks. Conventional rheometers are usually limited to measure the rheological parameters of debris-flow of fine particles. Slump-tests has been used to evaluate the flow behaviour of fresh concretes which allow the tested concrete slurries to have larger particles. In this study, the relationship between the parameters obtained from rheometer measurements and slump tests for debris-flow slurries with/without big particles were investigated. At the initial stage, we used fine-sediment slurries to conduct rheological experiments to find the relationship between the parameters obtained from the rheometer measurements and slump tests. The rheological parameters of slurries were measured using the ‘Brookfield DV-III rheometer’. The rheological behavior of the slurry samples used in this study follow the Bingham fluid model. Rheological parameters (i.e., yield stress and viscosity) are affected by the concentration of slurry, indicating that the higher the concentration, the greater the value of the rheological parameters. Slump test was then conducted using the same material samples prepared for rheometer test and the slumped height and spreading diameter of the tested sample were measured. The result shows that the slump height ratio and spreading ratio of the tested slurry decrease with the increase of slurry sediment concentration. Experimental sediment slurry samples were prepared by mixing coarse sands of about 1 mm in diameter. Our results show that the parameters obtained by rheometer measurements are closely related with those by slump tests for the slurries used in this study, indicating that there is a high potential to evaluate rheological parameters of debris-flow using a slump test as an alternative method.