## 2 Experimental Investigation
### Preparation of Soil Slope  
Referring to the international standard sand and the sand used in the typical fault dislocation model test [57; 58; 59; 60], the standard sand of the test soil sample in this study was determined, with its particle size distribution curve obtained through a sieve analysis, as shown in Figure 2. The coefficient of uniformity (Cu) was 2.73. The internal friction angle of sand is 28\({}^{\circ}\) by direct shear test. Through the compaction test (vibration hammer test), the maximum dry density of sand is 1675 kg/m\({}^{3}\). The relative density of sand is 67%. The slope model was created by first compacting the soil to form a level ground and then excavating it into a slope. This process involved incrementally placing the soil sample into the model box in batches. Based on the designed damping number determined from preliminary tamping tests, each 15 cm layer of soil was leveled and then compacted to 10 cm using a tamper (Figure 3a). This layered compaction process was repeated uniformly until the overlying soil layer reached a thickness of 100 cm (Figure 3b). The slope contour was then marked on an acrylic glass plate to ensure that the completed model slope exactly matches the dimensions of the conceptual model. Finally, the soil near the marked contour was excavated, and the slope was shaped until the preparation was complete, as illustrated in Figure 3. To minimize the boundary effects on soil deformation patterns, we specifically designed the experiment by incorporating low-friction materials--specially designed PVC films--applied to the inner side of the soil box to reduce the influence of friction on soil movement. \begin{table}
\begin{tabular}{c c c} \hline
**Physical Quantity** & **Similarity Relationship** & **Similitude Parameter** \\ \hline L: Geometric dimensions & \(C_{L}\) & 40 \\ \(\rho\): Density & \(C_{\rho}\) & 1 \\ g: Gravity & \(C_{g}\) & 1 \\ \(\tau\): Soil pressure & \(C_{\tau}=C_{L}\cdot C_{\rho}\cdot C_{g}\) & 40 \\ a: Slope acceleration & \(C_{a}\) & 1 \\ \hline \end{tabular}
\end{table} 
Table 1: Similarity relationship table of a slope physical model. Before the formal commencement of the experiment, we conducted physical and mechanical parameter measurements of the test soil. Initially, we performed the moisture content and particle size distribution analyses of the test soil to ensure the uniformity of its  
Figure 3: Preparation of a soil slope cross-bedrock fault: (**a**) Layered compaction; (**b**) Tamped to 100 cm; (**c**) Slope preparation; (**d**) Slope forming. Figure 2: Particle gradation curve diagram of the procured sand. moisture content and particle gradation. Subsequently, we conducted vibration hammer tests (for sand) to obtain the maximum dry density of the test soil. Following the steps and operations of the compaction test, we poured the test soil into the soil box and leveled it to a depth of 15 cm, then compacted it with a homemade tamper to a depth of 10 cm, and compacted it in layers to a depth of 1 m. A random soil layer was sampled with a ring cutter for direct shear tests and compaction tests, since the study aims to simulate the abrupt dislocation of active faults of bedrock under strong earthquakes and analyze the seismic damage response of buildings and the deformation and destruction of the covering layer site. That is, the shear strength parameters of the test soil were determined through quick shear tests. Finally, the compaction coefficient was obtained based on the ratio of the actual measured dry density in the box to the maximum dry density obtained from indoor compaction tests. Taking into account the impact of the compaction of the upper soil layer on the lower soil layer, we sampled the lower soil layer for compaction coefficient determination after each layer was compacted.