Additional Earth Pressure of Retaining Wall Caused by Vehicle Load

Abstract

The additional load caused by vehicles is an important consideration in the design of highway retaining structures. This study investigated the additional earth pressure of retaining wall caused by vehicle load. Combined with the construction of a cantilever retaining wall in the Liandu-Jinyun section of 330 National Highway Expansion Project, a series of soil pressure boxes was embedded above the floor of the retaining wall and on the inside of the vertical plate. After the wall was constructed, a 30 t dump truck was used as the load source and asked to stop at designated places, the additional vertical and lateral earth pressure caused by vehicles (static load) was tested, and the test results were compared with the calculated results obtained using the standard uniform distribution method in the current highway design code and the Boussinesq solution of elastic mechanics. Results reveal that the additional lateral earth pressure along the wall shows a nonlinear distribution, the maximum value appears in the middle of the wall, and the peak value decreases as the distance of the truck from the retaining wall increases. The distribution pattern of additional vertical earth pressure on the floor in the cross-section direction is also non-linear. Agreat difference exists between the measured and calculated results. Using the uniform distribution method to determine the additional lateral earth pressure caused by the vehicle load may underestimate the bending moment or anti-overturning moment resulting from the additional lateral earth pressure, which may cause failure of the anti-bending and anti-overturning abilities of the retaining wall to meet the requirements. For the variable section retaining wall (the wall section size decreases with the wall height), the shear strength of the middle and upper parts of the wall may be insufficient, and shear failure may occur. The tested additional lateral earth pressure is basically the same as the Boussinesq solution, but the vertical additional earth pressure is larger than the Boussinesq solution. This study suggests the use of the Boussinesq solution with multiple lanes and standard vehicles as the additional load caused by vehicle when designing the retaining wall (especially heavy duty road retaining wall).