Centrifugal Model Test Study On The Influence Of Vegetation Roots On Slope Stability

In recent years,the slippage of unsaturated soil slopes with roots under rainfall has become a hot topic in environmental geology and environmental geotechnical engineering research.A large number of data related to geological disaster accidents show that rainfall is the most common environmental factor that induces landslides and reduces slope stability.Therefore,it is of great exploration value and practical significance to conduct experimental research on the shallow landslides covered by vegetation under rainfall conditions and analyze the effects of vegetation roots on slope stability.This paper starts with the vegetation root system and uses a combination of theoretical analysis,centrifugal model test and numerical simulation to thoroughly study the deformation method and direction of root-bearing slope under the action of seepage,direction,movement route and scale,and discusses the opposite root forms The impact of slope stability.The main results obtained are as follows:(1)Developed a set of test equipment that can increase the water level in the centrifuge and simulate the root transpiration.The device includes a slope water level control system,a root transpiration simulation system,and a slope instability recording system..The monitoring and recording of stress and strain,seepage path,displacement and deformation,and matrix suction change in the slope during the whole test are realized,and the test process can be adjusted remotely through the real-time observation screen.(2)In the experiment,the wet front gradually moved from the back of the slope to the slope.Under the action of seepage,the unsaturated slope soil gradually transitioned to saturation,and the matrix suction of the soil continued to decrease,which reduced the effective stress and shear strength of the soil.The model occurred damage.Summarize the destruction process and phenomenon characteristics of each group,and the model of vegetation slope damage triggered by water level rise can be defined as a progressive damage that starts from the middle and lower parts of the slope and extends upwards,and can be divided into slow according to the characteristics of the damage There are four stages of deformation,rapid instability,small deformation after failure and stability.(3)The model roots were made with three typical root forms of tap,plate,and heart as representatives,and tested in groups.By comparing the apparent instability,water migration,and deformation characteristics of each group,the existence of the root system improved the slope stability Nature,limiting the scope of landslide instability and delaying the time of landslide occurrence.The influence of the different root types on the slope stability is mainly reflected in the reinforcement depth and the ratio of the reinforcement area to the slope area.The increase in the reinforcement depth will delay the time of the failure of the slope.The larger the reinforcement area,the initial settlement of the slope top Will be smaller.(4)Based on the Saito model,a classic landslide early-warning model,in-depth analysis of the slope displacement and deformation yields a 20 mm / d landslide displacement and deformation early-warning threshold,that is,when the slope continuously generates a deformation rate of 20 mm / d,the Issue a 3-day alert.If the slope has root reinforcement,the warning interval will be prolonged,the time for tap root and plate root will be extended to 5days,and heart root will be extended to 13 days.(5)On the basis of the model test,according to the parameters such as the depth and scope of the root system reinforcement,the soil-soil characteristic curve of the slope body,etc.,the geotechnical numerical simulation software used to restore the test loading process by reasonably setting the boundary conditions.The transpiration was simulated to quantify the stability improvement of the slope body under the reinforcement of the root system,and the determined safety factor value was obtained.It is found that the transpiration effect is very obvious to improve the stability of the slope body.At the same time,comparing the three root systems,the Heart type root has the best reinforcement effect due to the maximum reinforcement depth and reinforcement range,and the safety factor of the reinforced slope body is relative to the tap type The roots and plate-type roots were significantly improved by22.7% and 89.7%.