MSE Walls Supporting Gravity Wall Traffic Barriers
Very often MSE walls will have to support gravity wall traffic barrier. In such cases, the gravity barrier and the MSE would have to be designed for impact loads, and consider the interaction between the two systems. Up to now, in older MSE software the interaction effects have been calculated by approximate means, where the bearing stresses in the MSE wall were treated as a uniform surcharge. In the updated DeepEX version, the interaction between the two systems automatically accounts for the actual calculated bearing pressure distribution. Traction forces are also computed along the gravity wall base and applied.
Figures 1 through 3 present the surcharge impact stresses on the MSE wall for various conditions with the bearing stress component calculated with a one-way stress distribution approach. As it can be seen, considering the actual trapezoidal bearing pressure distribution significantly affects how impact stresses are calculated on the MSE wall.
While it is common to use the one-way distribution, if we were to use elasticity equations, then the impact stresses would be significantly increased on the upper MSE reinforcements as seen in Figure 4. However, it is felt that such modelling is neither realistic nor would it produce the greatest force demand on MSE reinforcement.
Figure 1: Impact Surcharge on MSE without impact load and without traffic surcharge
Figure 2: Impact Surcharge on MSE with traffic surcharge only
Figure 3: Impact Surcharge on MSE with traffic surcharge and Impact Load
Figure 4: Impact stresses with theory of elasticity