## 3 Results and Discussion
### ITS Response of Slope Anchorage System  
The variation of anchor bolt axial force at monitoring points ITS-1-ITS-3 during the model test is shown in Figure 8c. The monitoring points ITS-1-ITS-3 exhibited ITS response. Axial force reduction was observed during Stage-1 and Stage-2. At 20 min, anchor bolt axial forces at monitoring points ITS-1-ITS-3 decreased by 24.7%, 20.4%, and 40.2%, respectively, compared to their initial values. These reductions were caused by runoff-induced erosion at the interface between the retaining structure and slope (Figure 8a), combined with the unevenness of the physical model laying, which amplified force variations at monitoring point ITS-3. By 50 min, the axial force change rates at monitoring points ITS-1-ITS-3 were 4.4%, 2.6%, and \(-\)5.1%, respectively, relative to the values at 20 min, indicating that the surface erosion effect is close to the upper limit [36]. Within 5 min of Stage-4 initiation, hydraulic fluctuation caused the expansion of the structural planes, weakening the stability of the rock blocks in the anchoring section of the anchor bolt; therefore, the anchor bolt axial force showed a decreasing trend [9]. Groundwater pressure variations increased sliding forces in heavily weathering rock blocks. When sliding forces exceeded anti-sliding forces, fractured rock blocks began to slide, causing abrupt axial force surges at monitoring points during 59-60 min. The unloading response of ITS components shows that the slope  
Figure 7: Variation of pore water pressure and slope failure characteristics: (**a**) Initial state; (**b**) Plane failure of slope; (**c**) Variation of pore water pressure. deformation exceeded 2.2 mm. Notably, the peak axial force at ITS-1 aligned with the unloading response observed in the uniaxial tensile test. Figure 8b confirms that torsional deformation of the retaining plate generated ITS-compatible displacement patterns. During 60-90 min, rock sliding rates gradually declined, and axial force fluctuation was caused by surface runoff. The variation of anchor bolt axial force at monitoring points ITS-4-ITS-6 is shown in Figure 9c. The ITS response characteristics appear at ITS-4 and ITS-5. After 10 min loading of Stage-1, axial forces at monitoring points ITS-4-ITS-6 exhibited reductions of 19.7%, 70.2%, and 31.7%, respectively, compared to the initial state. As shown in Figure 9a, a local erosion pit was caused by inhomogeneity during the model construction process. During Stage-2 and Stage-3, axial forces at monitoring points ITS-4-ITS-6 exhibited consistent reductions. By 50 min, the axial forces at monitoring points ITS-4-F-6 had decreased by 23.8%, 20.2%, and 21.3%, respectively, compared to  
Figure 8: Variation of axial force at monitoring points ITS-1, ITS-2, and ITS-3 and slope failure characteristics: (**a**) Slope surface characteristics during block sliding; (**b**) Plane failure caused anchor bolt tension; (**c**) variation of axial force. Figure 9: Variation of axial force at monitoring points ITS-4, ITS-5, and ITS-6 and slope failure characteristics: (**a**) Slope surface erosion characteristic; (**b**) Tension crack caused by block slide; (**c**) Variation of axial force. their measurements at 10 min. Rainwater softening and runoff scouring were identified as the primary contributors to persistent preload degradation. Figure 9 demonstrates a significant deepening of the seepage-induced damage zone at 50 min. The overall sliding of the anchoring system and the rock block occurred at 59 min. As shown in Figure 9b, the rock blocks slid and formed tension cracks in the weathering transition zone. The axial force at monitoring points ITS-4-ITS-6 did not increase significantly due to the failure of the local anti-sliding effect. The variation of anchor bolt axial force at monitoring points ITS-7-ITS-9 is shown in Figure 10c. The ITS response characteristics were observed at monitoring points ITS-7-ITS-9.