碎石桩与抗滑桩联合加固斜坡软弱地基路堤的工作机理分析

Working Mechanism of Embankment over Sloped Weak Ground Reinforced by Combination of Gravel Piles and Slide-resistant Piles

为进一步明确碎石桩与抗滑桩联合加固斜坡软弱地基路堤的工作机理,本文建立无加固措施、碎石桩加固、抗滑桩加固及碎石桩与抗滑桩联合加固斜坡软弱地基路堤的FLAC3D数值分析模型,研究4种工况土体的水平位移、竖向沉降及抗滑桩桩身内力与变形。结合正交设计方法,探讨斜坡软弱层土体重度、黏聚力和内摩擦角对抗滑桩桩身最大弯矩的影响权重排序。碎石桩、抗滑桩加固斜坡软弱地基分别可以明显约束竖向沉降、水平位移,而碎石桩与抗滑桩联合加固能同时削减竖向沉降及水平位移。碎石桩加固斜坡软弱地基,潜在滑动面一定程度上移;联合加固时抗滑桩桩身内力及变形较直接进行抗滑桩加固有较大幅度衰减,斜坡软弱层土体内摩擦角的变化对抗滑桩桩身最大弯矩的影响远大于黏聚力与重度变化。所获结论有益于碎石桩与抗滑桩联合加固斜坡软弱地基路堤时抗滑桩设计技术改善。

To further make clear the working mechanism of embankment over sloped weak ground reinforced by combination of gravel piles and slide-resistant piles, a numerical model of embankment over sloped weak ground was established based on FLAC3D software. The soil horizontal displacement, vertical settlement, the internal forces and deformation of slide-resistant piles under four kinds of working conditions were discussed, including embankment without reinforcements, embankment reinforced by gravel piles, embankment reinforced by slide- resistant piles and embankment jointly reinforced by gravel piles with slide-resistant piles. Orthogonal experi- mental design method was conducted to study the order of influence weights of unit weight, cohesion and inter- nal friction angle of sloped weak layer soil on the maximum moment of the slide-resistant piles. The vertical settlement and horizontal displacement can be reduced significantly using gravel piles and slide-resistant piles respectively, while both the vertical settlement and horizontal displacement can be reduced significantly using gravel piles jointly with slide-resistant piles. The potential sliding surface will move up to a certain extent after embankment reinforced by gravel piles. Compared with embankment reinforced by slide-resistant piles directly,the internal force and deformation of the slide-resistant piles will be decreased substantially when using gravel piles jointly with slide-resistant piles. The influence of the variation of the internal friction angle of sloped weak layer soil on the maximum moment of slide-resistant pile is much larger than that of variation of soil cohesion and unit weight. The conclusions are benefitial to the improvement of slide-resistant pile design when gravel piles and slide-resistant piles are applied to reinforce the embankment over sloped weak ground.