铁路桥梁根式挖井基础桥墩的水平承载特性研究  

Horizontal bearing characteristics of the railway bridge piers on root-digging well foundations

作　　者：李涛 陈兴冲[1] 王义 鲁锦华 张熙胤[1] 丁明波[1] LI Tao;CHEN Xingchong;WANG Yi;LU Jinhua;ZHANG Xiyin;DING Mingbo(School of Civil Engineering,Lanzhou Jiaotong University,Lanzhou 730070,Gansu,China)

机构地区：[1]兰州交通大学土木工程学院,甘肃兰州730070

出　　处：《地震工程学报》2024年第1期174-181,共8页China Earthquake Engineering Journal

基　　金：国家自然科学基金面上项目(57178142)。

摘　　要：根式基础作为一种新型变截面结构形式,已被证明对于提高沉井基础与桩基础的竖向及横向承载力有明显影响,但其对挖井基础抗震性能的改善作用尚不明确。为明确根键对挖井基础桥墩承载力特征的影响,对一铁路根式挖井基础桥墩进行拟静力试验,研究其滞回曲线与骨架曲线特性,通过建立符合试验的有限元模型,讨论不同根键参数对挖井基础桥墩耗能能力及承载力的影响。结果表明根键的存在充分带动了周围土体的参与度,可大大提高挖井基础桥墩的承载力,且随着墩顶位移荷载的增加承载力呈非线性增加。试验及数值模拟均表明:根式挖井基础的破坏主要是由基础周围的土体失效引起的,基础自身并未发生损坏;增加根键的长度可以明显提高根式挖井基础桥墩的承载能力与耗能能力;当根键之间的间距大于根键自身宽度时,增宽根键可明显提高根式挖井基础桥墩的承载能力与耗能能力,而当根键的间距小于自身宽度时,加宽根键对承载力的影响不明显;增加根键的数量能明显提高根式挖井基础桥墩的承载力;在基础底部布置根键的效果并不弱于在侧壁布置,且根键布置在侧壁时不宜靠近土体表面。研究成果可为根式挖井基础在我国铁路桥梁中的应用提供科学依据。As a novel variable section foundation,a root foundation can increase the vertical and horizontal bearing capacities of the caisson and pile foundations;however,its effect on the seismic performance of a digging well foundation remains unclear.To clarify the influence of roots on the bearing capacity characteristics of a pier on a digging well foundation,a pseudostatic test was conducted on a railway pier on a root-digging well foundation to examine the characteristics of its hysteretic and skeleton curves.By establishing a finite element model for use in this test,the influence of different root parameters on the energy dissipation capacity and bearing capacity of the pier was discussed.The results show that roots can improve the bearing capacity of the pier on the digging well foundation by fully promoting the participation of the surrounding soil,and the bearing capacity increases nonlinearly with displacement load on the pier top.Test and numerical simulation show that the damage to the root-digging well foundation is mainly caused by the failure of the soil around the foundation;however,the foundation is not damaged.The increase in the length of roots evidently improves the bearing capacity and energy consumption of the pier on the root-digging well foundation.Only when the spacing between the roots is greater than the root width does widening the roots obviously improve the bearing capacity and energy consumption of the pier.Increasing the number of roots obviously improves the bearing capacity of the pier.The effect of arranging roots at the bottom of the foundation is not weaker than that at the side wall,and the roots should not be near the soil surface when they are arranged at the side wall.The research results provide a scientific basis for the applications of root-digging well foundations in railway bridges in China.

关 键 词：根式挖井基础 桥墩 承载力特征 拟静力试验 参数分析 

分 类 号：U442[建筑科学—桥梁与隧道工程]