Study On The Reinforcing Effect Of Plant Roots On Embankment Slopes

The implementation of the strategy of ecological protection and high-quality development of the Yellow River Basin provides a once-in-a-lifetime opportunity for ecological restoration and water and sand control in the Yellow River Basin.The stability of the channels and embankments has become an important factor affecting the safety of flood control.The ecological fragility of the middle and upper reaches of the Yellow River basin,the complex geological conditions and the uneven distribution of rainfall cause scouring damage on the backwater side of channels or embankments,resulting in disease in channels and embankments.Plants can effectively inhibit soil erosion and shallow landslides and act as a natural protective barrier for the soil.The root system of plants can strengthen the soil and improve the stability of the slope on the backwater side of the embankment,while the root system also absorbs water from the soil particles to reduce the pore water pressure,thus enhancing the soil’s resistance to damage.Research on the effects of plant slope protection,slope stabilisation,soil conservation and erosion reduction on the backwater side of embankments in the middle and upper reaches of the Yellow River is of great scientific significance in guiding ecological restoration and preventing embankment sliding in the Yellow River basin.In this paper,a triaxial shear test was conducted to quantify the reinforcing effect of roots on the slope of a root-bearing loess at different water contents.The analytical solution for the slope safety factor under rainfall conditions was derived and compared with the numerical simulation results.Soil moisture sensors and matrix suction meters were used to monitor the changes in matrix suction in the middle and foot of the slope under different rainfall intensities and to analyse the erosion of the slope surface and the water holding capacity of the slope under different rainfall periods.The analytical solution is compared with the model solution.The results show that.(1)Comparing the change curves of water content 8% and 10%,it can be seen that as the water content increases,the peak residual strength is increased and the time to peak is delayed,the strain softening phenomenon is weakened at 14%-17% water content and a stable peak strength can be maintained;the closer the specimen is to the optimum water content,the more obvious the root reinforcement effect is,and at the same water content,as the perimeter pressure increases,the peak partial stress is reached after adding the root system Under the same water content,the time to reach the peak partial stress is delayed with the addition of roots,and the larger the perimeter pressure is,the greater the proportion of roots to improve the mechanical parameters of the soil.(2)The shortest flow production time is 6 minutes on bare slopes and the longest is 12 minutes on bermudagrass slopes,the shorter the flow production time,the less water infiltration and the easier it is to enter the erosion stage of the slope;the slope is adjusted to 30 degrees,45 degrees and 60 degrees for comparison experiments,the steeper the slope,the shorter the flow production time,the earlier the turbidity of rainwater and the earlier the time from turbidity to clarity;the rise of the slope causes the slope surface The increase in the slope causes an increase in the runoff velocity and strengthens the water resistance of the slope.The maximum mass of sediment washed from the bare slope in 24-36 minutes was 15.2g at the test slope of 30 degrees,while it was 14.7g at 60 degrees.(3)The displacement caused by rainfall on the slope is related to the rainfall seepage,and the shape of the wetting front shows an obvious cumulative effect of rainfall,after the rainfall ends,the slope undergoes obvious overall damage,the top of the slope collapses,the foot of the slope rises and deflects,and the greater the rainfall,the greater the displacement and deformation of the landslide body.Under the condition of rainfall intensity of 160ml/min,3000 mL of rain fell,including surface runoff of 1890 ml,infiltration of 1110 mL,infiltration rate of 37%;under the condition of rainfall intensity of 160ml/min,3000 mL of rain fell,including surface runoff of 1941 ml,infiltration of 1059 ml,infiltration rate of 35.3%.(4)The longer the rainfall time in the early stage and the greater the rain intensity,the greater the difference between the safety coefficient of the slope after the rain and before the rain after 24 hours.Under the same rainfall holding time,the more obvious the concave curve of the slope safety factor under heavy rainfall intensity is,the longer it takes for the slope to return to the safety factor before the rainfall.The slope safety factor under each rainfall duration cannot rise to the pre-rainfall safety factor after 24 hours.(5)The slope safety coefficient decreases with the increase of rainfall,and the safety coefficient decreases to 2.84 after 24 hours under heavy rainfall,and the rate of decrease accelerates with the increase of rainfall intensity.With the increase of rainfall,the difference between the model solution and the analytical solution gradually decreases,the model solution is larger than the analytical solution at the beginning of the rainfall under medium rainfall intensity,and the model solution is smaller than the analytical solution after 15 hours,the analytical solution is always smaller than the model solution under heavy rainfall intensity,and the difference between the two increases with the increase of rainfall,the maximum difference between the analytical solution and the model solution is 0.06 under the continuous effect of heavy rainfall.(6)The safety coefficient decreases faster in the early stage of rainfall and slows down gradually in the later stage;the greater the rainfall intensity,the faster the slope safety coefficient decreases;the decrease of soil matrix suction under the action of heavy and torrential rainfall is obviously faster than that under the action of light and medium rainfall;the greater the rainfall intensity,the faster the rate of rainfall infiltration and the more adequate the rainfall infiltration.