风驱雨作用下植被斜坡稳定性响应研究

Response of vegetated slope stability under wind-driven rain conditions

闽东南高植被覆盖区台风暴雨型滑坡频发,探索在植被、降雨、强风作用下的滑坡失稳演化及其规律对揭示高植被覆盖区台风暴雨型滑坡的成灾机制、监测预警具有重要的理论及实际意义。以福建省永泰县洋斜滑坡为研究对象,对斜坡上的毛竹进行拉拔试验以及对根土区进行单环入渗试验,结合Green-Ampt模型和无限边坡模型,研究在台风暴雨作用下植被土坡的稳定性响应规律及其稳定性分析方法。结果表明:(1)毛竹抵御的极限风速主要在18~30 m/s的范围之内,对应8~11级风力范围。(2)毛竹迎风区土体入渗能力随着风速的增长而增长,0~12 m/s内入渗能力基本不变,12 m/s以上入渗能力迅速增长。(3)根土区湿润锋的迁移速度随着风速和降雨强度的增大而加快,台风通过植被扰动土体形成优势渗流,对入渗的影响主要在于加快了湿润锋的迁移速度。风−雨−植被协同作用下,风速是影响土体入渗能力的重要因素。(4)台风暴雨作用下风荷载通过植被加快根区土降雨入渗,从而增大湿润锋迁移速度,是台风暴雨型滑坡孕灾、成灾的重要环节。

Landslides frequently occur in heavily vegetated areas of southeast Fujian Province due to typhoon rainstorms.Investigating the failure mechanisms and evolution patterns of landslides influenced by vegetation,rainfall,and strong winds is crucial for disaster mechanism,monitoring,and early warning of typhoon-induced landslides in densely vegetated regions.This study focuses on the Yangxie landslide in Yongtai County,Fujian Province,investigating response patterns and analysis methods for vegetated slope stability under wind-driven rain conditions.Pulling tests on moso bamboo and single-ring infiltration tests were conducted,integrating the Green-Ampt model and infinite side slope model.Detailed main results include:1)Bamboo’s maximum wind resistance ranges from 18 m/s to 30 m/s,corresponding to wind forces of 8 to 11.2)Soil infiltration capacity in the windward area increases with wind speed,remaining constant at 0-12 m/s but rising rapidly beyond 12 m/s.3)The wetting front’s migration speed in the root-soil zone accelerates with increasing wind speed and rainfall.Typhoons disturb soil by swaying vegetation to create preferential flow,mainly accelerating the wetting front’s migration speed.Wind speed significantly impacts soil infiltration capacity under wind,rain,and vegetation interactions.4)During typhoon rainstorms,wind loads enhance rainfall infiltration in the root-soil zone through vegetation,thereby speeding up the wetting front’s migration.This process is critical for typhoon-induced landslide occurrence and development.