The optimal mix proportion design method of similar transparent materials in soft soil foundation

Transparent synthetic materials with similar physical and mechanical properties to the natural soft soil are fundamental for studying the failure mechanism of tunnel excavation in a soft soil foundation using a visual model test. Therefore, this paper generated a quantitative method for determining an optimal mix proportion of transparent cemented soil. Firstly, Fused quartz particles (coarse aggregate), Nanoscale hydrophobic fumed silica powder (binder), and N-dodecane mixed 15# white oil (pore fluid) were selected as the raw materials to prepare transparent cemented soil, and systematic orthogonal experiments were designed (two influencing factors and three levels). Concurrently, the physical and mechanical characteristics of transparent cemented soil were analyzed in three aspects: physical nature, compressive characteristics, and shear properties. Subsequently, to represent the relationship between various physical and mechanical parameters (unit weight, internal friction angle, cohesion) and different influencing factors (the particle size of quartz sand, the mass ratio between fumed silica and fused quartz) quantitatively, multiple nonlinear regression equations of various physical and mechanical parameters (unit weight, internal friction angle, cohesion) were obtained by fitting the original test data. Finally, the particle size of quartz sand, the mass ratio between fumed silica and fused quartz, and the geometry similarity constant were solved, combining the obtained multiple nonlinear regression equations. In addition, applying the designed method achieves uniformity in properties between the transparent material and natural soil. All the conclusions could provide theoretical support and data reference for transparent soil model test implementation.