Experimental study on concrete box culverts in trenches

Concrete box culverts are widely used in expressways in mountain areas.Many problems frequently take place due to improperly estimated vertical earth pressures on culverts.The prevailing Chinese General Code for Design of Highway Bridges and Culverts(CGCDHBC)stipulates the computation of the design load on culverts primarily based on the linear earth pressure theory,which cannot accurately describe the variation of the vertical load on culverts in trenches.In this paper,a full-scale experiment and numerical simulation were conducted to evaluate the variation of vertical earth pressures on culvert and soil arching in backfill.The variations of foundation pressure and settlement were also analyzed.The result revealed that the soil arch forms when the backfill on the culvert reaches a certain height.The soil arching effect reduces the stress concentration on the crown of the culvert but it is unstable.The vertical earth pressure on top of the culvert is significantly different from that recommended by the CGCDHBC.