基于土体破坏的路侧护栏立柱水平承载力计算

Horizontal Bearing Capacity Calculation on Roadside Guardrail Column Resulting from Soil Failure

由路边地基土体滑动造成的护栏立柱承载力失效是护栏系统丧失阻拦偏离道路汽车能力的原因之一,因此确定与土体滑动破坏有关的立柱水平承载力非常重要,本研究基于塑性极限理论对此进行了研究。首先,基于参考《公路交通安全设施设计细则》(JTG/T D81-2017)中计算立柱背面土重量方法建立了土体滑动几何体模型,在此基础上给出了几何体的静力平衡条件,采用摩尔-库伦准则描述几何体滑动面上剪应力与正应力的关系,推导得到立柱水平承载力的计算公式。由于公式是在几何体滑动满足几何容许场条件下获得的,根据塑性极限分析的上限理论,得到的公式为立柱水平承载力上限解,因此需要通过数值分析得到与理论精确解最为接近的解。对比表明,本研究给出的基于土体滑动失效的护栏立柱承载力公式计算结果与护栏立柱顶推试验结果符合良好。

The failure of guardrail column bearing capacity caused by soil sliding is one of the reasons why the barrier system loses the ability to block vehicles from deviating from road;therefore,it is crucial to determine the horizontal bearing capacity of columns related to soil sliding failure.This paper studies the above concern based on the plastic limit theory.Firstly,the slide geometric body model was established refering to the method to calculate the weight of soil behind guardrail column in‘Design Guideline for Highway Safety Facilities’(JTG/T D81—2017).Secondly,the conditions of static equilibrium of slide geometric body were established,and the equation for evaluation of horizontal bearing capacity of roadside barrier column was developed combining with Mohr-Coulomb rule of soil.Based on the upper bound theory of plastic limit analysis,the obtained formula was the upper bound solution of column horizontal bearing capacity;therefore,it was necessary to get the solution,which was closest to the exact solution by using numerical analysis.The result indicates that the proposed equation in this study agree well with the field test results.