考虑固结的新近吹填场地桩侧负摩阻力分布特性

Distribution characteristics of negative skin friction on piles installed at dredger fill sites considering consolidation effect

摘要:

为研究新近吹填场地中,因软土地基固结沉降引起的桩基侧摩阻力的分布特性,基于连续排水边界条件和理想弹塑性荷载传递模型,建立考虑土体固结效应的新近吹填场地桩基础变形分析理论模型。引入连续排水边界,求解双层地基的固结沉降,并采用理想弹塑性荷载传递法模拟桩侧位移-应力关系,求解桩侧摩阻力及桩顶沉降解析解。通过与试验数据进行对比,验证本文解的正确性,并讨论时间因子、双层地基厚度比、桩顶荷载和桩基受力对轴力以及侧摩阻力的影响。结果表明:随着时间的增加,负摩阻力增大,中性点下移；原位土层与新吹填土层厚度比增大,负摩阻力减小,中性点上移；随着桩顶荷载的增加,桩侧负摩阻力减小,中性点上移。

Abstract:

The paper aims to analyze the distribution of skin friction along piles caused by soil consolidation in newly formed dredger fill sites. Based on the continuous drainage boundary conditions and the ideal elastoplastic load transfer model, a theoretical model for the deformation analysis of pile foundations at newly filled sites was established considering the effect of soil consolidation. With the introduction of the continuous drainage boundary, the consolidation settlement of the double-layer foundation was acquired. The ideal elastoplastic load transfer method was used to simulate the pile shaft displacement-stress relationship, and the analytical solutions of skin friction and pile head settlement were obtained. Compared with experimental results, the proposed model was verified. The effects of time factor, thickness ratio of double-layer foundation, pile head load, and mechanics of pile foundation on axial force and skin friction were analyzed. Results show that as time increased, the negative skin friction increased and the neutral point of the skin friction moved downwards. When the thickness ratio of in-situ soil layer to new dredger fill layer increased, the negative skin friction decreased and the neutral point of the skin friction moved upwards. With the increase in the pile head load, the negative skin friction decreased and the neutral point moved upwards.