中文摘要：

为研究红黏土上硬下软地层中开口管桩的土塞问题,对3种不同直径的镀锌开口管桩进行室内静压沉桩模型试验,以分析单桩、群桩土塞高度的变化规律和红黏土地层管桩土塞效应的机理。结果表明：土塞高度随着管桩压入深度的增大不断增大,当桩压入到红黏土层上硬下软界面（硬塑层和可塑层交界面）后,土塞高度停止增长,持续到压入可塑层一定深度后土塞高度继续增长直到压桩结束,表明土层类型对土塞效应影响显著;土塞高度与压桩顺序关系并不明显,单桩与群桩的土塞高度基本相同;所有的管桩均在到达红黏土软塑层时出现土塞完全闭合的情况,管桩由硬塑层打入软塑层时,土塞闭塞作用很强;从软塑层打入持力层过程中,土塞增量填充率变大较明显,土塞闭塞作用减弱。

英文摘要：

To study the soil plug problem of the open-ended pipe pile in the red clay layer that the hard was in top and the soft in low,the indoor jacked pile-sinking model tests of three sorts of different diameter pipe piles were carried out,and change rule of soil plug height for the single pile,the group pile and the mechanism of red clay pipe pile soil plug effect were analyzed. Results showed that the soil plug height was with the increase of pipe penetration depth,when the pipe was pressed into the red clay layer interface（the interface of hard plastic layer and plastic layer） that the hard was in top and the soft in low,the soil plug stopped growing,and the situation contimued until the pipe was pressed into certain depth of plastic layer,then the soil plug continued to grow until the press pipe ended. That showed that the soil types had remarkable influence on the soil plug effect; the relation of soil plug height and pipe pile pressed in order was not obvious,the soil plug height of single pipe and the group pipe was basically the same; all the pipe pile would closed soil plug completely when the pipes were pressed into red clay plastic layer,the soil plug occlusion effect was very strong when pipe pile was pressed from hard plastic layer into plastic layer; the incremental filling ratio was increased obviously and the soil plug occlusion effect was weakened in the process of from plastic layer into bearing layer.