坡面沉桩边坡动态稳定性三维极限上限分析

Three-dimensional transient stability of slopes during pile driving using upper-bound limit analysis

采用极限分析上限法,建立土质边坡坡面沉桩动态稳定性三维计算模型,研究沉桩力、桩土间横向力等对边坡动态稳定性的影响。通过算例计算,对整个沉桩过程中边坡抗滑稳定安全系数的变化规律及其内在机制进行深入研究,并分析桩径、沉桩位置、坡角对边坡抗滑稳定安全系数的影响规律。结果表明:沉桩力对边坡稳定性产生不利影响,导致沉桩前期边坡安全系数持续降低;桩体穿过破坏面后,边坡安全系数由于桩身的抗滑作用而显著提高。桩径越大,沉桩前期安全系数越低,其下降速度也越快,但桩体穿过破坏面后安全系数提升也越明显;沉桩位置越靠近坡顶,沉桩过程中安全系数下降速度越快,导致最危险点的安全系数越低;坡角越大,沉桩过程中整体安全系数越低。分析结果对于坡面沉桩的稳定性评估及设计施工具有一定参考价值。

A 3D rotational failure model for calculating the transient stability of a slope during pile driving was established based on the upper-bound limit analysis. The influences of the pile driving force and the lateral force between pile and soil on the slope stability were considered. The variation of the anti-slide safety factor of the slope during pile driving was analyzed in detail through examples. The parametric studies were carried out to explore the effects of pile diameter, pile location and slope angle on the anti-slide safety factor of the slope. The results demonstrate that the pile driving leads to a steady decrease of the safety factor during the earlier stage of pile driving and the safety factor increases significantly because of the anti-sliding effect of the pile body after the end of pile reaching the sliding surface. The greater the pile diameter is, the lower the safety factor is and the faster it drops during the earlier stage of pile driving. The closer to the top of the slope the pile location is, the faster the safety factor decreases and the lower the safety factor of the most dangerous depth is. The safety factor decreases dramatically with the increase of the slope angle during the whole process of pile driving.