Method for calculating embankment load induced vertical stress increments under reinforced concrete box culvert − a case study

Abstract

For the convenience of designing reinforced concrete (RC) box culverts in road/railway transportation systems, a practical graphic method for evaluating the vertical stress increments under an RC box culvert has been developed. Firstly, like Osterberg’s method, influence values for the vertical stress increments under the shoulder, the middle of the slope, and the toe of an embankment have been newly produced in graphic forms. Secondly, a graphic form correction factor (α₁) has been created to consider the vertical load difference between an RC box culvert location and the both side embankments. Then multiplying the vertical stress increments from an embankment load by α₁, the desired vertical stress increments under an RC box culvert can be obtained. The method was applied to a road RC box culvert in Saga, Japan, to demonstrate its usefulness. With the evaluated vertical stress increments, settlements under the RC box culvert were calculated and they are comparable with the field measurements. Further investigation about this case history regarding to the effects of soil–cement columns under the box culvert was carried out by finite element analysis.