Experimental study on proportioning of similar transparent materials in soft soil foundation on orthogonal design

A visual model test is an effective method to study the failure mechanism of tunnel excavation in a soft soil foundation, and the transparent synthetic materials with similar physical and mechanical properties to the natural soft soil is the premise. Therefore, this paper proposed a collocation method for similar materials. Firstly, fused quartz sand (coarse aggregate), nanoscale hydrophobic fumed silica powder (binder), and n-dodecane mixed with 15# white oil (pore fluid) were selected to prepare transparent cemented soil. Subsequently, a systematic orthogonal test (2 factors 3 levels) was designed, and the main physical and mechanical parameters (unit weight γ, internal friction angle φ, cohesion c, compression modulus Es) were obtained by density and oil content test, standard consolidation test and consolidation fast shear test. Concurrently, the feasibility of transparent cemented soil was verified in three aspects: physical nature, compressor characteristics, and shear properties. Finally, variance analysis and range analysis were used to analyze the sensitivity of each factor, and the adjustment measures were developed to ensure the parameters of the transparent similar materials were consistent with the determined parameters. The research results provide theoretical support and data reference for the transparent similar material collocation used to simulate natural soft soil.