模拟降雨作用桩锚-加筋土组合结构加固边坡研究

Study on Simulated Rainfall Effect on Pile-anchor-reinforced Soil Combined Structure for Slope Reinforcement

桩锚-加筋土组合支挡结构在治理大型复杂滑坡中发挥越来越重要的角色。以某高填方山区机场滑坡为原型,进行降雨作用对桩锚-加筋土组合支挡结构加固边坡稳定性的模型试验研究。结果表明:①桩顶位移随注水时间产生三个阶段的变化:初期平缓发展阶段、突变增加阶段、再次平缓发展阶段。后排悬臂式桩桩顶位移变化量明显大于前排埋入式桩,因此,多排锚索抗滑桩加固边坡设计时,在后排桩悬臂情况下,宜考虑后排桩比前排桩截面尺寸大、锚索间距小来减小其桩顶位移,增强坡体稳定性;②填方边坡位移随注水时间变化,坡顶一级边坡位移量最大,随边坡级数增加,位移量减小,因此多级边坡加固可适当增加边坡锚索框架;③填方坡体沉降量随注水时间表现出后缘大、前缘小的趋势;④加筋土的变形与边坡坡体的变形一致,表明加筋土能够增强填方边坡的整体性;⑤各监测曲线最终均趋于平缓,表明桩、锚和加筋土组合支挡结构体系性能发挥良好。

The composite retaining structure with pile,anchor and reinforced earth plays more and more important role in the treatment of large and complex landslides.In this paper,considering the airport landslide in a high fill mountain area,a model test is carried out to study the rainfall effect on the composite retaining structures with piles,anchors and reinforced soil,which is used to enhance the stability of the slope.The test results show that:(1)There are three stages for the development of pile top displacement with the change of water injection time:the initial gradual increase stage,development stage,secondary gradual increase stage.The top displacement variation of the rear cantilever pile is larger than that of the front embedded pile.Therefore,when multi-row anchor piles are used to reinforce a slope and the rear row piles are cantilevered,it is recommended to install rear piles with larger cross-sectional areas than the front piles,and the spacing between anchor cables should be smaller,so as to reduce the pile top displacement and enhance the slope stability.(2)The displacements of the fill slope change with the water injection time,the displacement of the top slope level is the largest,and displacement decreases with the increase of slope levels.Therefore,the reinforcement of the multistage slope can appropriately increase the number of the anchor lattice beams.(3)It shows that the back edge of the filling slope has larger settlements that the front edge.(4)The deformation of the reinforced soil is consistent with that of the slope mass,indicating that the reinforced soil can enhance the integrity of the filling slope.(5)All the monitoring curves tend to be flat eventually,indicating the excellent performance of the pile-anchor-reinforced soil composite structure system.