## 3 Quantitative Analysis of Landslide Deformation Area
### Experimental Results and Analysis
On slopes with confining pressure, the pores between soil particles are small, rainwater infiltration is relatively difficult, and the soil water content is relatively small. Therefore, the degree of compaction of 81.54% of the base soil and the degree of damage of the slope without entrapment pressure is greater. In Figure 4 (6), the slope covered with low-density vegetation was the first large-scale destruction followed by the slope covered with general density vegetation, and finally, the slope covered with high-density vegetation, and the order of slope failure tended to be stable. Vegetation has a certain interception effect on rainfall, prevents the topsoil from being washed and eroded by rainwater, indirectly prolongs the time of slope failure, and the vegetation root system and topsoil interact to form a root-soil complex, which increases the shear strength of the slope, inhibits the development and damage of the slope, and reduces the final damage degree of landslide. The above three sets of experiments with different vegetation coverage obviously proved that slope stability is related to vegetation cover density; under the action of simple rainfall, different vegetation cover densities have different degrees of reinforcement on the slope, and the higher the vegetation cover density, the more obvious the effect of preventing landslides. Comparing the time points of large-scale destruction of area and volume, it can be seen that the volume change lags behind the area change to varying degrees in the time dimension. In Figure 4 (7), the slope damage degree is the greatest under the action of strong typhoon rain followed by typhoon rain, and the slope damage under the action of heavy rain is the smallest, which also proves that typhoons promote instability and damage of the slope, and the higher the wind level, the more likely the slope is to become unstable and the greater the degree of damage, which indirectly points out the limitations of vegetation protection in the presence of typhoons. It can be seen that experimental S11-S16 has an obvious initial failure stage, acceleration stage, and negative acceleration stage, and the change rate curve has multiple peaks, which belongs to the typical progressive retrogression failure. In summary, the degree of slope damage is strongly correlated with the seven influencing factors of the above study. According to the process of multiple groups of experimental damage, it can be found that there are some common points and differences in the process of destabilization damage of rainfall-type landslides. The similarities are as follows: the destabilization damage of the slope starts from the foot of the slope and the surface of the slope; the landslide goes through three stages from the beginning to the end, occurrence, development, and maturity stage; throughout the process of slope instability damage, landslide area changes precede volume stabilization to a certain degree of time; the essential reason of rainfall triggering the landslide, the infiltration of rainwater, on the one hand, leads to the softening of soil, and as the shear strength decreases, on the other hand, the water content of soil increases, the weight of soil itself increases, the sliding force increases, and when the down-sliding force is greater than the antisliding force is, the landslide will be produced. The difference is mainly reflected in that the failure process of the slope is different under different experimental conditions; the area, volume, failure speed, and time of landslide tending to be stable are different; and the failure mode of the slope is also different, which is generally divided into two types: push type and progressive pushback type.