组合荷载作用下斜坡上桩基础水平承载特性研究

斜坡上桩基础不仅要承担上部建筑物传递下来的竖向荷载,还要承担斜坡传递下来的土压力等水平荷载,构成了复杂的桩-土相互作用体系。为研究斜坡上桩基础在竖向和弯矩荷载作用下的水平承载特性,通过自行设计的组合荷载加载装置,开展了四种工况下斜坡上单桩室内模型试验。分析在组合荷载作用下桩顶沉降、水平位移、桩身弯矩、桩侧土压力以及地基比例系数m值变化规律。试验结果表明:在桩顶施加竖向荷载有利于提高单桩的水平承载力,减小桩身的水平位移、弯矩和桩前侧土压力;在桩顶施加弯矩荷载-不利于单桩的水平承载力,随着弯矩作用的增加,相同水平荷载作用下,桩身水平位移和桩前侧土压力明显增加,而水平荷载对桩顶的竖向沉降影响较小;地基比例系数不仅与桩周土体有关,还与施加的荷载类型和桩土交界处的水平位移有关,地基比例系数随桩土交界处水平位移的增加迅速减小,最后趋近于稳定。

Study on horizontal bearing characteristics of pile foundation on slope under combined load

The pile foundation on the slope not only bears the vertical load transferred from the upper building, but also bears the horizontal load such as the earth pressure transferred from the slope, forming a complex pile-soil interaction system. In order to study the horizontal bearing characteristics of pile foundation on the slope under vertical and bending moment loads, the indoor model tests of single pile on the slope under four working conditions were carried out by self-designed combined load loading device. The variation rules of settlement of pile top, horizontal displacement, bending moment of pile body, earth pressure on pile side and proportion coefficient m of foundation under combined load were analyzed. The test results show that applying vertical load on the top of pile can improve the horizontal bearing capacity of single pile and reduce the horizontal displacement, bending moment and soil pressure in front of pile;applying bending moment load on the top of pile is not conducive to the horizontal bearing capacity of single pile. With the increase of bending moment load, the horizontal displacement and soil pressure in front of pile increase obviously under the same horizontal load, while influence of the horizontal load on the pile top vertical settlement is small;the proportion coefficient of the foundation is not only related to the soil around the pile, but also related to the type of load applied and the horizontal displacement at the pile-soil interface. The proportion coefficient of the foundation decreases rapidly with the increase of the horizontal displacement at the pile-soil interface, and finally tends to be stable.