# Experimental Study on the Permeability of Ecological Slopes under Rainfall Infiltration Conditions
## 1 Introduction  
Rainfall is one of the main factors inducing slope instability [1; 2]. Under the action of rainfall, the slope failure type is shallow landslide. Most landslides occur during or after rainfall, and the critical time of landslide is related to the unsaturated permeability coefficient and shear strength of soil [3]. In order to reduce the occurrence of geological disasters such as slope instability, some scholars have studied the influence of anti-slide piles on slope stability [4; 5]. Therefore, the theory of pile foundation is also constantly improving and developing [6; 7; 8; 9]. At the same time, many scholars have put forward the method of ecological slope protection [10; 11]. Plant stems and leaves transpiration and root water absorption would reduce the water in the soil, increase the matrix suction of the soil, reduce the unsaturated permeability coefficient of the soil, and increase the shear strength so as to achieve the purpose of improving slope stability [12]. Therefore, it is of great theoretical and practical engineering significance to study the influence of different kinds of plants on slope permeability under rainfall. Up to now, a large number of scholars have carried out experimental research on soil permeability and achieved certain research results. [PERSON] et al. [13] designed an erosion test of rainwater on the slope and explored the rainfall erosion mechanism of argillaceous sandstone residual soil slope. [PERSON] et al. [14] carried out indoor rainfall tests on densefine-grained slopes and loose gravel slopes and systematically analyzed the effects of vegetation coverage on slope stability. [PERSON] et al. [15] studied the reliability of slope with a dominant seepage layer under rainfall infiltration. Taking a slope in Guangxi as an example, the reliability analysis of rainfall infiltration of the slope under rainfall was carried out. [PERSON] et al. [16] developed a one-dimensional soil column vertical infiltration model test device and proposed a new method for calculating the permeability coefficient of unsaturated soil. [PERSON] et al. [17] constructed a large-scale loess cover test base to carry out a series of rainfall tests and found that the permeability coefficient of the vegetation root growth area was higher than that of the non-vegetation. [PERSON] et al. [18] and [PERSON] et al. [19] established three vegetation cover layers and monitored the changes in water content and matric suction in each vegetation cover layer during the active period of rainfall and evaporation. It was found that the permeability coefficient of the straight root plant cover layer was the largest and the fibrous root plant cover layer was the smallest. [PERSON] et al. [20], [PERSON] et al. [21], and [PERSON] et al. [22] found that vegetation roots would enhance the permeability of the soil and the presence of vegetation under rainfall conditions would improve the stability of the slope. [PERSON] et al. [23] investigated the influence of slope gradient and compaction degree on the infiltration rate of slope rainwater by self-made rainfall and monitoring system. [PERSON] et al. [24] conducted rainfall experiments with different rainfall intensities for the loess slope model and explored the relationship between rainfall intensity and volumetric water content and matric suction. [PERSON] et al. [25] analyzed the influence of two common slope protection plants on slope rainwater infiltration through in-situ monitoring of engineering slopes and numerical simulations. [PERSON] et al. [26] carried out the seepage characteristics test of a fissured red clay slope by the fluorescence tracer method and explored the variation in the wetting front, transient saturation zone, and soil moisture content during rainfall.