Study On The Effect Of Vegetation On Slope Stability Under The Wind Load

Typhoon often occur in eastern coastal area of China during a normal year. Thetyphoon brought heavy rain,and usually accompanied bystrong wind load.Undertyphoon geological hazard, such as landslides and debris flow, are easily induced inweak geological environment of areas. Statistical analysis of the survey data oftyphoon geological hazards in WenZhou region. The result show that the vegetation ofslop is more developed in the ramp of typhoon geological disasters.Therefore, thevegetation and geological disaster of typhoon has some relevance.In this paper, Status of vegetation cover in WenZhou and the date of landslidesinduced by typhoon combine to determined fir, pine and bamboo as a typicalvegetation types. Statistical analysis of relevant literature and research data,According to the distribution characteristics of typical vegetation types in space andrelated physical and mechanical parameters, The simplified model of three kinds oftypical vegetation was bulided. Using AR model to simulate the wind speed curve,andstress analysis on the simplified model. Furthermore,The numerical model of threetypical vegetation slope was establishment, numerical calculation carried out,theinfluence of the vegetation to slope stability under wind load is to be discussed. Thewriter got several conclusions as following:The horizontal shear of bamboo root-soil simplified model get maximal value,thepine take the second place,and the China fir get minimum value. The root system ofBamboo is shallow,the horizontal shear are easily more than the shear capacity of thesoil and root-soil composite, and easily occur shear failure. The horizontal shear of firroot-soil composite were lower shear capacity of root-soil composite and thesurrounding soil.The value of horizontal shear of Masson pine root-soil composite in acertain depth is greater than the shear capcity of the complex and the surroundingsoil.Therefore,it may be shear deformation or damage in root-soil composite and soil.The anti-bending capacity of Bamboo root-soil composite is relatively small,sothe whole root-soil composite prone to slip,resulting in dumping. The anti-bendingcapacity of fir root-soil composite is greatly, the possibility of deformation and failurewas less. The anti-bending capacity of fir root-soil composite is stronger and significantly larger than the moments, so the whole complex less prone to slippage.Roots enhances the mechanical properties of surface soil, changing the stressfiled of the slope. Different vegetation types have different effects of soilreinforcement. The deep of effect of Bamboo root system is shallow, the effect of soilreinforcement only acting on the surface of slope. Influence of Bamboo on slopestability is very small. The root system of China fir and Masson pine is deep, the deepof potential slip surfaces is deeper than the cohesive soil slopes, slope stability hasbeen greatly improved.The horizontal displacement of leeward slope increases gradually under theaction of wind loads. The plasticity district gradually extended from the toe of slope towithin of slope along the depth of root-soil composite, thus they accelerating thedeformation and failure of slope significantly. The response of windward vegetationslope to wind load is limited to the toe of slope, the applied load can’t cause changes,so the impact to the overall stability of the slope has little effect.Under wind loads, the plasticity district of China fir and Masson pine graduallyextended from the toe of slope to within of slope along the depth of root-soilcomposite, the horizontal displacement is gradually increased until keeps constant, sowind load have promotion effect on the deformation and failure of slope. With theapplied load, the process of deformation and failure are different. Comparativelyspeaking, the acceleration time of deformation of China fir slope is later than Massonpine slope.The plasticity district of Bamboo slope concentrated on the surface ofslope, so Bamboo prone to windthrow. so the effect of Bamboo to the overall stabilityof the slope has little effect.In this paper, the research results can provide a reference for the study oftyphoon geological disasters, and provide some guidance for the select of vegetationprotection and prevention of typhoon geological disasters.