## 3 Quantitative Analysis of Landslide Deformation Area
### Experimental Results and Analysis  
The damage areas of 16 groups of landslide experiments were quantitatively identified, and the quantitative analysis curves of landslide deformation areas were drawn, as shown in Figure 4. The longitudinal axis direction is divided into four parts, namely, a-cumulative area percentage curve, b-cumulative volume percentage curve, c-area rate of the change curve, and d-volume rate of the change curve. The horizontal axis direction is divided into seven parts, which are the seven influencing factors studied: (1) rainfall intensity (S1--30 mm/h, S2--65 mm/h, S3--140 mm/h), (2) slope angle (S4--30\({}^{\circ}\), S2--45\({}^{\circ}\), S5--60\({}^{\circ}\)), (3) slope crest (S2--20 cm, S6--none), (4) base soil compaction (S7--75.71%, S8--81.54%), (5) confining pressure (S9--yes, S10--none), (6) vegetation cover density (S11--low density, S12--general density, S13--high density), and (7) typhoons (S14--none, S15--typhoon, S16--strong typhoon). Table 2 summarizes the characteristic points of 16 groups of landslide experimental failures, which are the time point of landslide onset, the time point when the damage tends to stabilize, the maximum value of area and volume after the failure tends to stabilize, and the peak value of area and volume change rate. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Experiment**} & **Start of Damage** & **Damage Tendency** & **Area** & **Volume** & **Peak Area Change** & **Peak Volumetric Rate** \\  & **Time (min)** & **Time (min)** & **Maximum (\%)** & **Maximum (\%)** & **Rate (\%/min)** & **of Change (\%/min)** \\ \hline S1 & 92.5 & 112.5 & 97.42 & 11.13 & 16.15 & 2 \\ S2 & 37.5 & 72.5 & 99.97 & 12.93 & 15.14 & 2.25 \\ S3 & 2.5 & 37.5 & 99.99 & 35.68 & 19.99 & 3. In Figure 4 (1), the greater the intensity of rainfall, the sooner the slope undermines and stabilizes. After the slope became stable, the slope surface of the three groups of experiments was completely destroyed, resulting in the landslide area accounting for nearly 100%, but the proportion of landslide volume after stabilization was different. After the shallow damage of the slope, the higher rainfall intensity made the slope go deeper to the direction of destruction, and the secondary damage occurred on the slope under the  
Figure 4: Quantitative identification curves of landslide: (**a**) represents the cumulative area percentage curve, (**b**) represents the cumulative volume percentage curve, (**c**) represents the area change rate curve, and (**d**) represents the volume change rate curve. action of 140 mm/h rainfall intensity, and the landslide volume accounted for the highest proportion in all experiments, reaching 35.68%. The instability mode of the progressive failure led to a single peak except for the double peak curve of the volume rate of change corresponding to the 140 mm/h rainfall intensity. In Figure 4 (2), the larger the foot of the slope, the earlier the slope would be damaged on a larger scale. The 60\({}^{\circ}\) slope also collapsed, and its final damage area was close to 100%. Among the three different slope angle slopes, the 45\({}^{\circ}\) slope finally had the largest failure volume, and 30\({}^{\circ}\) was the smallest. The 30\({}^{\circ}\) landslide was a progressive receding failure, and the corresponding area change rate and volume change rate had multiple small peaks. In Figure 4 (3), the landslide area and volume of the slope roof platform are much larger than those without the slope crest, which is also echoed by the landslide area change rate and volume change rate, indicating that the existence of the slope crest will seriously affect the stability of the slope. In Figure 4 (4,5), 75.71% of the compaction degree of the base soil corresponds to the situation of confining pressure. Lower base soil compaction makes it easier for rainwater to infiltrate the base layer than higher soil compaction, resulting in relatively low water content in the shallow layer of the slope.