桥梁沉井基础竖向承载力及破坏机理研究

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中图分类号：TU47 文献标志码：A DOI： 10.15935/j.cnki.jggcs.202504.0017

AbstractIn recent years，caisson foundations have gained increasing popularity as a foundation solution for bridge towers and piers due to their favorable mechanical properties.This study investigates the vertical bearing capacity and failure mechanisms of bridge caisson foundations in sand through numerical simulations and theoretical analyses.First，the effects of key parameters—including caisson plan size，embedment depth， and soil efective internal frictionangle—on the vertical ultimate bearing capacity andsoil failure modes are systematically examined via numerical modeling.Subsequently，a theoretical formula for calculating the vertical ultimate bearing capacity at the caisson base is derived.Based on the numerical results，fitting formulas for the geometric parameters of the base failure mode are further proposed，incorporating factors such asembedment depth，depth-to-width ratio，aspect ratio，and soil internal friction angle.The numerical simulations reveal that when vertical failure occurs in the caisson foundation，the base contributes over 90% of the totalbearing capacity，accompanied bya distinctlocalized shear failure pattern in the soil surrounding the caisson base.By integrating the geometric parameters of the failure modeinto the theoretical formula for vertical ultimate bearing capacity，this method enables eficient prediction of the bearing capacity during the preliminary design stage of bridge caisson foundations.

Keywordsbridge caisson foundation，vertical bearing performance，numerical simulation，theoretical analysis， local damage mode，geometric parameter

0 引言

近年来，具有大质量大刚度的沉井基础因其整体性强、稳定性好、能承受较大的静力竖向荷载和水平荷载1，同时在地震荷载等动荷载作用下也有很好的表现3-9，被众多跨海和跨江桥梁用作桥墩、桥塔的基础，例如我国的沪苏通长江公铁大桥、泰州长江公路大桥、常泰长江大桥，日本的明石海峡大桥、多多罗大桥等。（剩余16809字）