砂土中沉井加桩复合基础水平静力及循环模型试验

Model tests on a caisson-pile composite foundation in sand subjected to lateral static and cyclic loadings

采用自主设计的水平循环加载装置进行模型试验研究,探讨了水平静力及循环加载下单体沉井及沉井加桩复合基础承载变形性能。试验研究表明:与单体沉井基础相比,沉井加桩复合基础的水平刚度耦合了沉井及群桩刚度,改善了水平荷载作用下基础的位移响应模式,其水平承载力明显高于单体沉井基础。水平双向对称循环加载后,基础的水平刚度、承载力均有所提高,并且循环加载后沉井加桩复合基础的承载力高于单体沉井基础。因此,针对水平循环加载而言,沉井加桩复合基础是一种更为有效的基础形式。

Model tests are carried out using a lateral cyclic loading rig developed by the authors in order to investigate the bearing capacity and deformation characteristics of a simple caisson foundation and a caisson-pile composite foundation in sand under lateral static and cyclic loadings. Test results reveal that the lateral stiffness of the caisson-pile composite foundation couples the stiffnesses of caisson and group piles compared with that of the simple caisson foundation, and it improves the deformation response of the foundation under lateral loading. The bearing capacity of the caisson-pile composite foundations is significantly higher than that of the simple caisson foundation. Meanwhile, the lateral stiffness and bearing capacity of foundation increase after the application of lateral bidirectional and symmetric cyclic loading, and the bearing capacity of the caisson-pile composite foundations is higher than that of the simple caisson foundation after cyclic loading. The caisson-pile composite foundation is a more effective solution to increase the capability of the foundation in resisting the lateral cyclic loading.