中文摘要：

针对粉土中吸力桶在吸力沉贯中的两个关键性问题———沉贯阻力和内部土体稳定性，在自行研制的试验平台上进行了一系列吸力桶沉贯模型试验。试验结果表明，粉土中吸力沉贯时，Andersen 所提供的基于 CPT 锥尖强度的阻力计算公式能较好预测阻力发展趋势，但计算结果偏小；而修正的承载力公式预测结果在沉贯前期与实测值较吻合，沉贯后期预测偏大。吸力沉贯前期，贯入阻力随深度稳步增长，直到贯入深度达到某个临界值后，阻力增长缓慢甚至保持不变。桶内粉土在吸力作用下的失稳机理与黏土或砂土不同，在渗透力作用下表现为从土层表面开始的自上而下管涌或渗流侵蚀。沉贯后期，端部土体在较高水头差下发生失稳并向桶内流动，造成了桶内土体密度降低，端阻力与内壁摩阻力降低，总贯入阻力主要由外壁摩阻力提供。并结合有限元模拟对上述实验现象的内在机理进行了解释。

英文摘要：

A series of model tests were conducted to investigate the penetration resistance and soil plug stability during the caisson installation in silt. Some useful conclusions could be drawn from the tests results： Andersen’s resistance calculation method that was based on cone tip resistance could be used to predict the overall trend of the resistance, but with underestimated results. While the predicted results by the modified bearing capacity method coincide well with the measured results during the initial stage of the installation process, but with overestimated results during the late period. The total soil resistance increased steadily with depth during the beginning stage, but rose slowly or remained constant after reaching a certain depth. The failure mechanism of the silt plug was different from that of clay or sand, caused by the seepage induced soil piping or erosion from up to down. During the late period of installation, the soil around the caisson tip level got plastically deformed under the high hydraulic gradient and flowed into the caisson,loosening the density of the soil plug and ultimately reducing the internal side friction and tip resistance, making the total soil resistance mainly comprise external side friction. Numerical simulations were also performed to aid understanding the observed results.