岩质边坡桩柱式桥墩的受力分析研究

Stress Analysis on the Pile-column Bridge Piers in Rock Slope

岩质边坡上桥梁基桩具有承重与阻滑双重功能,其受力性状远比抗滑桩和平地上两侧无坡度的单一倾斜受荷桩要复杂得多。本文在探讨和总结了桩柱式桥礅双排桩的受力特点和计算方法的基础上,采用大型通用非线性有限元分析软件MSC.Marc对其进行数值模拟,建立了岩质边坡桥梁双排基桩三维有限元计算模型,通过计算得到了岩质边坡的应力分布情况。由于桩柱式桥墩桩顶横向连梁对桩顶的约束作用,桩身变形特征也发生了明显变化,桩柱式桥墩前、后两根基桩的侧移曲线均有桩顶弹嵌的特征,使得桩身受力更加合理,对桩身材料强度的要求相对有所降低;此外,以该模型为基础,分别分析了基桩间距变化、桩体刚度变化、嵌岩深度变化及桩周岩(土)体性质变化对桩柱式桥礅双排桩受力及位移的影响,其计算结果可用于指导岩质边坡桥梁基桩的设计及施工。

The bridge pile foundation in rock slope has double function of bearing load from super- structure and counteracting landslide-thrust from pile foundation side, and the mechanical behavior of pile in rock slope is much more complex than pile foundation in flat ground. In the paper, based on considering stress characteristics and calculation methods, the nonlinear finite elements analyze software MSC. Marc was adapted to have numerical simulation and establish three-dimensional elastoplastic model for the bridge double-row piles in rock slope. The stress of the bridge double-row piles in rock slope was achieved arid the calculation results show： the deformation characteristics of piles have obvious change with constraint effect of crossbeam in pile top and the stress of piles appear more rational because of elas- tically fixed in pile top. Base on the same model, the influence factors variation included pile spacing, pile rigidity, shaft fixity depth and rock （soil） property for stress and displacement were considered and analyzed, and calculation results have guidance on pile foundation design and construction in rock slope.