Experimental study on the effects of tree planting on slope stability

Ecological engineering is an effective method to control mountain disasters, in which tree roots play an important role in stabilizing the slope and consolidating the soil in face of the landslide. The use of artificial roots to simulate real root is an important means of experimental research. To explore which tree planting patterns could achieve better stability on slopes of 20°, 35°, 50°, and 60° under extreme climatic conditions (rainfall intensity of 118 mm/h), this paper used an artificial root model to construct four types of slopes, i.e., slope with dense trees planted on wide bands, slope with dense trees planted on narrow bands, slope with equally and sparsely planted trees, and barren slope (control group). Sixteen groups of indoor slope rainfall experiments were carried out. To determine the stability effects of different slopes, the failure process and model of slopes during rainfall were analyzed, and the safety factor values Fs were calculated. The following conclusions are drawn: (1) Trees have different effects on the stability of slopes with different slope gradients. Planting trees on 20° and 35° slopes has good reinforcement effect, but planting trees on 50° or 60° slopes will lead to less stability. (2) The optimal planting patterns are different for different slopes. For example, the optimal planting pattern on the 20° and 35° slopes is wide-band dense planting, while it is not suitable to plant tall trees on the 50° and 60° slopes. (3) The change of slope gradient will not affect the failure mode of barren slopes but will change the failure process for vegetated slopes. (4) Wide-band dense planting pattern on all slopes can effectively intercept sediment, inhibit sediment slide, and prevent collapse. All in all, the research results provide a good theoretical guidance and practice to control landslides with ecological engineering.