An experimental exploration on the creep behaviour of fine-grained soils containing diatoms microfossils and insight...

Soils containing diatom microfossils is found in different regions of globally marine environments, and exhibits soil properties defying classical soil mechanics. Although the physical and mechanical properties of such soil have been explored, research on its creep characteristics remains limited, leading the creep deformation mechanism unclear. In this study, an artificial diatomite was prepared using diatom powder, kaolinite, montmorillonite, and illite. Triaxial consolidated undrained shear and creep tests were conducted to explore the hydromechanical and creep properties. The microstructure evolution was observed using laser particle size analyzer, scanning electron microscope, and mercury intrusion porosimeter. Besides, the applicability of the creep component model to diatomite was explored. The results showed that for soils containing diatom powder have a higher coefficient of consolidation (1.0 × 10^-5m²/s) which is independent of confining pressure. Its failure under CU tests exhibited a barreling mode and strain-hardening process. As for the creep behavior, all diatomite soils under different stress level only exhibited attenuation creep, i.e., the strain rate decreased with time and creep strain was eventually stable. Based on these primary findings, it indicated that the hydromechanical and creep properties were influenced by the unique diatom structure. The numerous hollow pores in the skeleton resulted in a large coefficient of consolidation of diatomite. Additionally, due to frictional and interlocking effects between diatom particles, the undrained shear strength of diatomite was proportional to the confining pressure, and the creep curves showed attenuation creep. The fractional Maxwell model showed highest applicability to diatomite for this creep type. Meanwhile, microstructural observations indicated that there was no significant particle breakage before and after tests when confining pressure was lower than 500 kPa.