Abstract: The visual physical model testing technology based on transparent soils is playing an increasingly important role in the study of deformation and failure mechanism in geotechnical engineering. The preparation of transparent soils with high transparency, stable physical and mechanical properties, and suitable for simulating different natural rocks and soils is the basis for the development of this technology. Given the lack of transparent materials for clays and soft rocks, a transparent cemented soil has been formulated. The transparent cemented soil is synthesis using fused quartz as the skeleton particles, nano-level hydrophobic fumed silica powder as the cement and mixed mineral oil of n-dodecane and #15 white oil as the pore fluid. By changing the content or proportion of the cement, the particle size or gradation of the skeleton, a series of transparent cemented soils with similar refractive index and varying strength characteristics can be obtained. For the factors influencing the soil strength, such as cement content and skeleton gradation, 11 groups of controlled experiments were designed and corresponding triaxial shear tests were conducted to study the strength characteristics. Results show that: 1) The shear strength varies complexly with the changes of the particle size and gradation of the fused quartz, the content and proportion of the silica powder, etc., but overall the poor quality of quartz gradation and the rich proportion of silica powder reduces the shear strength. 2) By changing the preparation formulas, a series of transparent cemented soils with cohesions ranging from 5 to 65 kPa and internal friction angles ranging from 25° to 44° can be prepared, which provides a basis for the selection and preparation of transparent materials in physical model experiments using natural clays and soft rocks.

Key words: transparent cemented soil, preparation method, fused quartz, hydrophobic fumed silica powder, triaxial shear test, strength characteristics