多层土中根桩的非线性沉降简化计算方法

Simplified nonlinear method for settlement of root piles in multi-layered soils

根桩是一种新型桩基础,它通过从桩身预留位置将一定数量的水平根键顶入桩周土体中来提高桩基承载力。为分析多层土中根桩的非线性沉降问题,基于双曲线函数提出了土–根键的荷载传递模型,并推导建立了一种多层土中根桩的非线性沉降简化计算方法,基于MATLAB编制了根桩的非线性沉降分析程序。以安徽省池州长江公路大桥工程两根现场试桩为例,对该方法与现场荷载试验结果以及其它分析方法进行了比较。结果表明,该方法与实测结果吻合较好,较其它分析方法更符合根桩的荷载沉降曲线特性。根桩参数分析表明,根桩的荷载沉降特性对根键的布置型式以及根键侧壁土的荷载传递参数取值不敏感,但对根键底部土的荷载传递参数取值较敏感。

The root pile is a new type of pile,which improves the bearing capacity by penetrating a certain number of horizontal roots into soils from the reserved position of the piles.The load transfer model for the roots of a root pile is proposed based on the hyperbolic function,and a simplified nonlinear method for settlement of the root piles in multilayered soils is derived.An effective computer program based on MATLAB is developed for nonlinearly analyzing the load-settlement behavior of the root piles.The comparisons among the proposed method,other analytical methods and the root pile load test results on sites are carried out in terms of two real case root piles in Chizhou Yangtze River Highway Bridge in Anhui Province,China.It is demonstrated that the proposed method can achieve a good agreement with the measured results,and the load-settlement curve calculated by this method is more consistent with the real load-settlement characteristics of the root piles compared with that of the other analysis methods.The parameter study of the root piles shows that the load-settlement behavior of the root piles is not sensitive to the layout of roots and the load transfer parameters selected at root side-soil interface,but sensitive to the load transfer parameters selected at root base-soil interface.