系梁对哑铃型承台基础承载特性的影响研究

摘要:

针对我国大跨度桥梁目前常用的哑铃型承台基础,分析了系梁对基础承载能力特性的影响因素,建立FEA有限元模型,重点分析了系梁宽度及高度对哑铃型承台基础的基础承载特性影响规律,进一步讨论了系梁底设置桩基的合理性。结果表明: 随着系梁高度及宽度增加,系梁刚度变大,传递的剪力或弯矩增大,对上部结构荷载作用下基础承载力验算有利；但系梁自重也变大,对基础承载力验算不利。系梁自重引起的不利影响要远大于刚度增加带来的有利影响。在系梁底布置桩基可有效承载系梁自重,但对提高承台整体的承载能力并无明显益处。

Abstract:

The influence of tie-beam on bearing capacity characteristics of a dumbbell shaped pile-cap foundation was analyzed , this type foundation was widely used in long span bridges in China at present. FEA finite element model was established to selectively analyze the influence of the width and height of the tie beam on the foundation bearing characterstics of the dumbbell- shaped cap foundation. Furthermore, the rationality of setting pile foundation below the tie-beam was discussed．The results showed that As the height and width of the tie beam increase, the stiffness of the tie beam increases, and the transmitted shear or bending moment increases, which is beneficial to the calculation of the foundation bearing capacity under the superstructure load; However, the self-weight of the tie beam has also become larger, which is adverse for the calculation of the foundation bearing capacity. The adverse effect caused by the weight of the tie beam is much greater than the beneficial effect caused by the increase in stiffness. the pile foundation below the tie beam can effectively bear the weight of the tie beam, but the overall bearing capacity of the cap cannot be obviously improved with a pile placed below it．