微型桩组合结构加固边坡稳定性耦合分析

Coupled stability analysis for slope reinforced by micropile composite structure

采用数值分析方法,对微型桩组合结构加固边坡的稳定性进行耦合分析,通过分析微型桩组合结构加固前后边坡破坏模式的变化,系统研究微型桩组合结构的桩位、桩长、岩土类型及顶梁布置方式等对边坡稳定性的影响。研究结果表明:耦合作用下均质土边坡的破坏模式与微型桩组合结构的布设位置关系较大,对于常见的均质黏土边坡,将微型桩组合结构布置在边坡中上部能够取得更好的加固效果,微型桩的最优锚固长度约为滑面以上自由段长度的2倍;微型桩组合结构加固不同岩土类型边坡的效果相差较大,黏土和粉砂质边坡的加固效果较好,砂性土边坡的加固效果较差;顶梁布置形式对微型桩组合结构加固边坡效果有重要影响,采用行列式布置顶梁的效果优于锯齿状等顶梁布置方式。研究成果对微型桩组合结构加固边坡、滑坡的工程设计和安全评价具有借鉴意义。

Micropile composite structures were typically composed of micropiles and cap beams. They were common reinforcements used for slope stabilizing in emergency condition in recent years. Based on numerical analysis method, the coupled analysis was conducted on the stability of micropile composite structures reinforced slope. By comparing the failure modes of non-reinforced slope and micropile composite structures reinforced slope, the influence of pile location, pile length, pile connections and soil type was analyzed. The results show that the position of the micropile composite structures plays a dominating role in the slope failure modes. For a homogeneous slope, a larger safety factor is obtained when the micropile composite structures are placed in the middle-upper part of slopes, and the optimum ratio of anchorage length and free length is about 2.0. For different soil materials, stability of slopes with micropile composite structures is improved, but the level of its improved safety factor is different, reinforcement of silty and clayey slope with micropile composite structures is the best, but sandy slope with micropile composite structures is poor. Rigid pile caps connecting micropiles can obviously improve the safety factor of a reinforced slope, and the parallel micropile frame performs better than staggered arrangement. The results of this research can provide a useful basis for the design and stability analysis of slopes reinforced by micropile composite structures.