Dual effects of supergravity deformation and suction deformation on the determination of soil water characteristic curve by centrifugal testing method

Abstract

The centrifugal testing method for the soil water characteristic curve (SWCC) has found widely used in the fields of soil science, geology, and geotechnical engineering. However, the deformation of samples during the centrifuge testing process, resulting from the combination of matric suction (Ψ) and centrifugal force, introduces an error when compared to other SWCC testing methods. To quantify the influence of sample supergravity deformation on matric suction testing in centrifugal testing methods, a novel combined centrifuge-drying shrinkage testing method is proposed to differentiate the deformations caused by supergravity and Ψ during the centrifugal testing process. Meanwhile, the influence of different deformations on the SWCC of the soil was analyzed. On this basis, the scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) tests were conducted to explain the inherent mechanism of the centrifuge influence on soil water retention and deformation behaviors under supergravity conditions. The results indicate that, the drying shrinkage rule of the soil is different from the existing test rule. The SWCCs of soils with different initial dry densities (ρ_d) obtained through the combined centrifuge-drying shrinkage testing method follow the same desiccation path. Microscopic morphology and pore size analysis revealed significant influences of centrifuge dynamic disturbance and supergravity environment have great influence on soil pore structure during dehumidification.