研究饱和黏性土中静压沉桩引起的桩土界面孔压增量及有效径向应力的变化规律对工程实践具有重要意义。利用自制的大比例模型试验系统，通过双壁开口和闭口管桩，实现了开口和闭口桩桩身表面嵌入式安装微型测试元件，得到了考虑孔压增量的桩土界面有效径向应力的变化规律。研究结果表明：入土深度越大，桩土界面孔压增量及有效径向应力越大，闭口桩桩土界面超孔压大于开口桩；桩身上部桩土界面超孔压和有效径向应力小于桩身下部；同一入土深度，随着桩身h/L的增加，桩土界面土压力存在侧压力“退化”的现象；特定试验条件下，闭口和开口桩桩土界面超孔压与上覆有效土体自重比值最大值分别是61.2%和52.1%，桩土界面有效径向应力是超孔压的3.76~5.46倍。桩土界面超孔压和有效径向应力与桩身h/L位置有关。

It’s of great significance for engineering practice to study the variation of pore water pressure increment and effective radial stress at the pile-soil interface caused by jacked pile-sinking in saturated clayey soil. Embedded installation of micro test elements on the surface of the open and closed piles was realized. Then the effective radial stress of the pile-soil interface considering the increase of pore pressure was successfully obtained by using large-scale model test system and double-walled open and closed model pipe pile. The results show that the excess pore water pressure and effective radial stress of pile-soil interface increase with the embedded depth. The excess pore water pressure at the pile-soil interface of closed pile is greater than open pile. The excess pore water pressure and effective radial stress of upper part of pile is less than lower part of pile. At the same depth of penetration, with the increase of h/L of the pile body, there is a phenomenon of lateral pressure “degradation” in the soil pressure of the pile-soil interface. Under specific test conditions, the maximal ratio of excess pore water pressure of pile-soil interface and effective pressure of superimposed soil of open and closed pile are 61.2% and 52.1%. The effective radial stress of the pile-soil interface is 3.76-5.46 times of excess pore water pressure. Therefore, the change of excess pore water pressure and effective earth pressure of pile-soil interface are related to variation of pile locations of h/L at different penetration depths.

TU473.1

国家重点研发计划（2021YFE0113400）