Hydrologic And Mechanical Effects Of Vegetation On Slope In Yellow River Basin

In recent years of heavy rainfall caused by geological disasters caused the attention of people,for the slope protection,plant slope protection is governance landslide and debris flow disasters such as slope instability of important ecological methods,different with the traditional slope protection method,it greatly protects the slope of the original natural ecological environment,in accordance with the Yellow River basin ecological protection in China and development strategy of high quality.At present,domestic and foreign studies on plant soil fixation and slope protection generally focus unilaterally on the hydrological effects of vegetation,such as slowing rainwater infiltration and changing soil pore water pressure,or the mechanical effects of plant root reinforcement and anchoring,while relatively few studies have considered the hydrologic and mechanical effects.In addition,there are many kinds of common slope protection vegetation in different regions,and the effect of soil fixation and slope protection of that vegetation is better.There is no relatively perfect evaluation system,and the lack of research on these theories restricts the application of slope geological disaster prevention and slope protection in engineering.In this paper,three common slope protection plants in the Yellow River basin were selected,namely,Festuca arundinacea,Ligustrum lucidum,and Ophiopogon japonicus.Firstly,the rainfall infiltration test device was used to test.The moisture content distribution and suction distribution were measured by sensors,and the soilwater characteristic curve was fitted and the permeability coefficient was calculated.Then,direct shear test and root pull test were carried out on the three plants,and the variation rules of cohesion and internal friction Angle of the root soil complex were obtained,and the relationship between root diameter and maximum tensile strength and tensile strength was obtained.Finally,the commonly used geotechnical engineering software GeoStudio is used for simulation,and the two modules of SEEP/W and SLOPE/W in the software are coupled.Firstly,the unsaturated soil infiltration simulation of SEEP/W module is carried out to obtain the SLOPE pore water pressure,which is then applied to SLOPE/W module as the initial condition.The variation rule of slope safety factor with rainfall duration was obtained under different plant slope protection conditions.The study concluded as follows:(1)Plant roots can effectively reduce the peak value of soil volumetric water content,slow down the infiltration rate in rainwater soil,slow down the decline rate of suction,and increase the rainfall intensity,and improve the effect of infiltration.The SWCC data were fitted,and it was found that the air inlet pressure of Ophiopogon japonicus was the highest,the lowest in bare soil,and Festuca arundinacea and Ligustrum lucidum were in the middle.As for the permeability coefficient,the difference between the main regions of roots was obvious,the permeability coefficient of bare soil was the largest,and that of grass along the rank grass was the smallest.(2)The cohesion of bare soil and the three plants decreased with the increase of the saturation of root soil complex,and the cohesion of Festuca arundinacea root soil complex was significantly proportional to the root content,but the cohesion of Ophiopogon japonicus root soil complex and Ligustrum lucidum root soil complex increased first and then decreased with the increase of root content.The internal friction Angle has no obvious relation with the saturation and root content of the root-soil complex.The tensile strength of the three plants was negatively correlated with root diameter as a power function,and the tensile strength was also directly correlated with root water content.(3)Steady seepage is carried out under the boundary condition of annual average rainfall,The results show that the pore water pressure distribution on the surface of bare soil and three planted slopes is roughly the same.For the transient infiltration of rainstorm intensity,the effect of reducing the infiltration of Ophiopogon japonicus is the best.For slope protection effect under short-duration rainfall conditions:Ligustrum lucidum>Ophiopogon japonicus>Festuca arundinacea>Bare soil;For slope protection effect under long-duration rainfall conditions:Ophiopogon japonicus>Ligustrum lucidum>Festuca arundinacea>Bare soil.