DDC法复合黄土地基的原位浸水试验研究

发布时间：2019-03-13 11:43

【摘要】：针对黄土地区浸水载荷试验研究较少,在湿陷土层厚度为36.5m的兰州和平镇马兰黄土场地进行了持续时间为137d的DDC法复合地基的原位浸水试验研究,涵盖平整后场地的原位增湿、不同工况DDC桩处理地基及布设承台加荷浸水等阶段。试验结果表明:(1)桩长恒定,三桩间平均挤密系数λac随桩间距L的变化曲线可由Holliday公式表示。(2)承台总沉降量时变曲线呈现明显的"台阶"状,其陡增状态与水分的向下入渗引起桩侧及底部土体发生多次湿陷有关。(3)承台总沉降量时变曲线主要包括四个阶段,即陡增阶段、平稳阶段、缓增阶段与趋于稳定阶段;各阶段的拐点,可作为水分竖向运移规律研究的特征点位;各阶段沉降量增长形式差异与剩余湿陷量的发生方式有关。(4)承台周围地表隆起现象显著于地表沉降,可由地表隆起量的突变点位置及时间研究水分的水平运移规律。(5)DDC工法桩的建议合理间距为1.1m,桩长为20m。
[Abstract]:The in-situ immersion test of DDC method composite foundation with duration of 137 days was carried out in Ma Lan loess site of Heping Town, Lanzhou, where the thickness of collapsible soil layer was 36.5 m, and the in-situ immersion test of composite foundation with DDC method was carried out in the loess area with little research on immersion load in loess area. It covers the stage of in-situ humidification of leveled site, treatment of foundation with DDC piles under different working conditions and loading and soaking of cap. The experimental results show that: (1) the length of the pile is constant, the curve of the average compaction coefficient 位 ac between the three piles with the pile spacing L can be expressed by the Holliday formula. (2) the time-varying curve of the total settlement of the cap presents the obvious "step" shape. The steep increasing state is related to the multiple collapsing of soil at the pile side and bottom caused by the downward infiltration of water. (3) the time-varying curve of the total settlement of the cap mainly includes four stages, that is, the steepening stage, the steady stage, the slowly increasing stage and the steady stage; (3) the time-varying curve of the total settlement of the cap consists of four stages. The inflection point of each stage can be regarded as the characteristic point of the study on the vertical migration law of water. The difference of settlement growth forms at different stages is related to the occurrence mode of residual collapsibility. (4) the surface uplift around the cap is significantly higher than the surface subsidence. The horizontal movement law of water can be studied by the location and time of sudden change point of surface uplift. (5) the recommended reasonable spacing of DDC pile is 1.1 m and the length of pile is 20 m.
【作者单位】：河海大学岩土力学与堤坝工程教育部重点实验室;河海大学江苏省岩土工程技术工程研究中心;兰州理工大学;解放军后勤工程学院;
【基金】：国家自然科学基金(51379065,51579081) 中央高校基本科研业务费专项资金(2016B43414)
【分类号】：TU444

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