砂土中筒型基础沉放过程渗流特性和沉贯阻力研究

筒型基础的沉放是一项关键施工过程，沉放时土体在施工负压下产生渗流场，而渗流对基础筒壁的侧摩阻力和端阻力产生影响，导致沉贯阻力难以预测。针对这一问题，首先应用试验和数值模拟的方法，对筒型基础沉贯过程中的渗流特性进行分析，揭示筒壁两侧及筒端土体超孔隙水压力的分布；然后将分析结果应用于沉贯阻力的推导中，并对推导的公式进行验证。研究表明：筒型基础沉贯过程中，筒壁两侧土体的超孔隙水压力沿筒壁深度几乎呈线性变化，在接近筒端时出现非线性变化；不同的沉贯深度下，渗流对沉贯阻力的影响不同，随着沉贯深度的增加，减小的阻力占总沉贯阻力的比值越来越大；通过推导的理论公式计算的试验模型和实际工程的沉贯负压理论计算值与实测值吻合较好。

Research of seepage characteristics and penetration resistance during installation of bucket foundations in sand

The penetration of the bucket foundation is a vital construction procedure. Seepage field is generated in the soil under the suction pressure during the penetration. The seepage has an influence on the friction along the skirt wall and on the resistance of the skirt tip, which leads to the difficulty in predicting penetration resistance. In order to solve this problem, firstly, the methods of experiment and numerical simulation were applied to analyze the seepage characteristics of the bucket foundation during the penetration; moreover the distribution of the excess pore water pressure along the bulkhead and skirt tip was revealed. Thereafter, the analytical results were applied to derive the penetration resistance, and the derived theoretical formulae were verified. The results show that during the penetration of the bucket foundation, the excess pore water pressure of the soil changes linearly along the depth of the skirt, but becomes nonlinearly near the skirt tip. The effect of seepage flow on the penetration resistance is different for different penetration depths; the reduced resistance caused by seepage accounts is for a greater proportion of the penetration resistance with increasing penetration depth. The suction pressure of the test model and practical engineering calculated by the theoretical formulae are in good agreement with the measured values.