Numerical Analysis of Low-Fill Box Culvert under Rigid Pavement Subjected to Static Traffic Loading

Abstract

This paper presents a numerical study on culverts under rigid pavements subjected to static traffic loading. The numerical study was based on the results of a comprehensive field study of a single-cell low-fill box culvert under three roadway sections (concrete pavement, concrete shoulder, and unsurfaced fill). The culvert in the field test was instrumented with displacement transducers and pressure cells to capture the deformations and pressures resulting from different combinations of wheel loads from a test truck pulling a low-boy trailer loaded with a backhoe. Deflections under the culvert roof and pressures on the culvert were measured during loading. Properties of soil and pavement layers were determined in the laboratory. A three-dimensional (3D) numerical model of the culvert was developed using a finite-difference program. The numerical model with material properties was verified with the field test results. A parametric study was conducted to investigate the influence of cement concrete pavement thickness, fill depth, and culvert span on the load distributions over the culvert under wheel loads. The intensity of the vertical pressure gradually decreased with an increase in the pavement thickness, fill depth, and culvert span. However, the effect of the span on vertical pressures decreased with a top slab designed to control excessive deflections. The comparison of the calculated vertical pressures by the numerical method and the AASHTO distribution methods demonstrated that the current AASHTO pressure distribution methods are overly conservative for the wheel load distribution on a low-fill box culvert under a rigid pavement.