微型桩–加筋土挡墙的模型试验和数值模拟分析

Model test and numerical analysis of micropile-MSE wall

微型桩–加筋土挡墙是一种适用于山区陡坡地带公路工程的新型路基支挡结构,为了初步检验其工作机制和效果,通过模型试验,并结合有限元模拟,对微型桩加固前后的斜坡加筋土挡墙在多级附加荷载下的静力响应进行对比研究。结果表明:数值计算手段能够较好地再现模型试验结果;在2~10 kPa附加荷载下,实测微型桩–加筋土挡墙的沉降比加固前减小11%~40%,面板侧向位移减小50%~66%,且附加荷载越大,减小的比例越大;同时,基底压力和侧向土压力也比加固前明显降低;倾斜桩对挡土墙变形的限制发挥着更为重要的作用,实测2~10 kPa附加荷载导致的倾斜桩身弯矩比竖直桩高出25.9%~40.3%,因而有必要采用较高强度的微型桩作为倾斜方向的加固构件。研究结论初步验证了微型桩–加筋土挡墙的有效性,可为其在实际工程中的应用提供指导。

The micropile-meehanically stabilized earth（MSE） wall suitable for roadway construction in steep terrain of mountainous areas is a new type of earth retaining structure. To validate its working mechanism and effect, model tests and numerical simulation were conducted to study the multilevel surcharge induced static response of MSE walls on slope before and after the micropile reinforcement. The results indicate that the numerical method can simulate the model tests well. Under the surcharge loadings of 2 - 10 kPa, the measured subsidence of micropile-MSE wall is reduced by 11% - 40% compared to that of unreinforced model, whereas the wall deflection is reduced by 50% - 66%. The higher the surcharge loading, the larger the reduction is. The base and lateral earth pressures are also decreased notably. The inclined micropiles in the micropile-MSE wall play a more important role in the deformation control, which lead to a 25.9% - 40.3% higher bending moment in the inclined piles than in the vertical piles under the surcharge loadings of 2 - 10 kPa. Therefore it is necessary to use the micropiles of higher strength as the inclined reinforcement in the MSE wall. Thus, the reliability of the micropile-MSE wall is verified preliminarily.