桩承加筋路堤中褥垫层对桩土应力调整的影响分析

Numerical Analysis of Influence of Cushion on Pile-Soil Stress Adjustment in Pile-Supported Embankment

桩承加筋路堤中褥垫层对桩土应力的调整起了十分关键的作用。桩土应力比是桩土应力调整结果的直接表现,而路堤土拱效应以及褥垫层刚性承台效应对荷载调整作用正是桩土应力调整过程的体现。利用有限元对路堤荷载下PCC单桩以及加固范围内的土体进行了数值模拟。通过分析认为,褥垫层对桩土应力调整的过程和结果均会产生影响,随着褥垫层模量、厚度、粘聚力以及内摩擦角的增加,土拱效应虽会遭到削弱,但褥垫层刚性承台作用明显增强,最终导致更多的荷载转移到桩体上,桩土应力比增加。通过总结认为,改善褥垫层性质,加强其对桩顶局部压入作用的限制是保证桩体承担较多荷载的关键。

Except for the stiffened platform effect of geogrid-reinforced cushion, the soil arching effect of embankment also has an effect on the stress adjustment between pile and soil. Both stiffened platform effect and soil arching effect are affected by the cushion, so the cushion becomes a key part in pile-supported embankment for pile-soil stress adjustment. Pile-soil stress ratio is the obvious result of the stress adjustment between pile and soil, and the efficiency of stiffened platform effect and soil arching effect reflects the process of stress adjustment. On the basis of the numerical analysis, cushion has influences on both process and result of stress adjustment between pile and soil. With the increase of cushion modulus, thickness, cohesion and friction angle, the soil arching effect is weakened, but the stiffened platform effect has been strengthened, which result in more loads have been supported by pile directly and the pile-soil stress ratio has also been increased. The conclusion also shows that the key point of transferring more loads to pile is to limit the penetration of pile into cushion.