## 2 Introduction to the Experiment  
### Test Material and Apparatus Arrangement  
This paper derives from a practical construction project and its test prototype parameters, as detailed in Table 1. To enhance the simulation of an authentic tunnel construction process and capture the effects of variations in the mechanical behavior of peripheral rock support, the indoor physical model test is conducted at a scale of 1:45. The similarity ratios for stress, elastic modulus, and cohesive force can be deduced by integrating the three fundamental theorems of similarity theory with the basic equations of elasticity: \(C_{\sigma}=C_{E}=C_{C}=45\). The displacement similarity ratio is \(C_{\delta}=45\). The strain similarity ratio is \(C_{\varepsilon}=1\). The internal friction angle similarity ratio is \(C_{\varphi}=1\).  
Following an examination of analogous materials in the surrounding rock, quartz sand was selected as the filling material, whereas lower-strength materials like clay or barite powder were chosen as the cementing material. Multiple sets of straight shear tests were conducted, and using iterative comparisons and analyses of model materials, the proportions of quartz sand, clay or barite powder, lubricant, and water were adjusted within a defined range to establish mechanical indices. The basic physical parameters of the tested soil are presented in Table 2.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Stratigraphy** & \multicolumn{2}{c}{**Physical Indicators**} & \multicolumn{2}{c}{**Mechanical Indicators**} \\ \hline \multirow{2}{*}{\
\begin{tabular}{c} Moderately \\ weathered \\ muddy siltstone \\ \end{tabular} } & Natural Density & Modulus of \\  & (kN/m\({}^{3}\)) & elasticity/(MPa) & Poisson’s ratio & Cohesion (kPa) & Angle of internal friction (\({}^{\circ}\)) \\ \multirow{2}{*}{
\begin{tabular}{c} Moderately \\ friction (\({}^{\circ}\)) \\ \end{tabular} } & \multirow{2}{*}{23.5} & \multirow{2}{*}{1758} & \multirow{2}{*}{0.34} & \multirow{2}{*}{654} & \multirow{2}{*}{33.21} \\  & & & & & \\ \end{tabular}
\end{table}
Table 1: Physico-mechanical parameters of a moderately weathered rock stratum.  
Following multiple tests, it was observed that the lining composed of barite powder exhibited a low modulus of elasticity and failed to meet the required similarity ratio. Consequently, the lining model material was altered to a mixture of gypsum, water, and a small amount of cement. The modulus of elasticity of the lining's analogous materials varies with the mass ratio of gypsum, water, and cement. To achieve the stipulated similarity ratio, unconfined uniaxial compressive strength tests were conducted on the lining's similar materials with different mix ratios, utilizing an electronic universal testing machine. The stress-strain curves and modulus of elasticity were measured, and after several tests, it was determined that the gypsum: water: cement ratio of 1:0.75:0.25 met the similarity requirements. The finalized mix yielded a similar material modulus of elasticity of 558.66 MPa.  
The primary objective of this test is to analyze the loading and deformation patterns of perimeter rock support induced by various construction sequences. The measured parameters encompass surface deformation, perimeter rock stress, and lining stress. Surface deformation is quantified using a percentage meter with a range of 0-10 mm and an accuracy of 0.01 mm, as depicted in Figure 1. The D