| Rainfall is one of the most important causes of instability and destruction of fill embankments.Landslides caused by rainfall are of common occurrence.As a natural engineer,plants have the function of preventing surface erosion and shallow landslides.And they are a low-cost,high-efficiency and environmentally friendly slope protection method.On the one hand,the root system of vegetation can reinforce the soil,on the other hand,they can also change the distribution of water and suction in soil through transpiration,and further change the soil strength.Taking the fill embankment as the research object,the construction section of Haizhou 2 of 204 National Highway was selected as the engineering background.Based on the finite element analysis software COMSOL Multiphysics,the influence of vegetation roots on the seepage and stability of the fill embankment was studied.The main research results are as follows:(1)The numerical simulation of seepage and stability analysis of unsaturated fill embankment considering rainfall was carried out.Based on the finite element analysis software COMSOL Multiphysics,the finite element calculation model of unsaturated fill embankment was established.The effects of three main factors,such as rainfall intensity,rainfall duration and rainfall type,on the seepage and stability of fill embankment were considered.The results show that when the rainfall duration and rainfall type are constant,the greater the rainfall intensity,the greater the pore water pressure and saturation in the slope,and the greater the displacement.When the intensity and type of rainfall are constant,the soil saturation and the displacement will gradually with the time passing by.When the total amount and total time of rainfall remain unchanged,the increase of saturation under intermittent rainfall is larger,and the pore water pressure and displacement are larger than that under continuous rainfall.(2)Taking Bermuda grass as slope protection plant,considering its transpiration and reinforcement,numerical simulation of seepage and stability of unsaturated fill embankment under rainfall with vegetation effect was carried out.Based on the finite element analysis software of COMSOL Multiphysics,the finite element calculation model of unsaturated fill embankment with vegetation was established.The influence of three main factors on seepage and stability of vegetated fill embankment is considered,including rainfall intensity,rainfall duration and rainfall type.The results show that the roots of plant can evaporate water into the air on the one hand and absorb water in the soil on the other hand.At the same time,plant roots can exert an additional cohesive force on the soil and improve the shear strength of the soil to a certain extent.As a result,compared with the bare soil,the pore water pressure and saturation of vegetation soil will decrease,and the displacement of vegetation soil will be smaller.Under the condition of short-term strong rainfall,the comparative analysis of seepage,displacement of vegetated and non-vegetated fill embankment was conducted.By comparing the displacements of the slope surface and the interior of the slope under different rainfall conditions,the most easily displaced place of the slope was obtained,and the relevant suggestions were put forward for practical engineering. |
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