OPTIMUM DESIGN OF REINFORCED EARTH WALLS WITH METAL STRIPS; SIMULATION-OPTIMIZATION APPROACH

Mechanically Stabilized Earth Walls (MSEW) and Reinforced Soil Slopes (RSS) are usually considered as cost-effective soil-retaining structures. By inclusion of tensile reinforcing elements in the soil, the strength of the soil can be improved significantly such that the vertical face of the soil/reinforcement system is essentially self supporting. Based on limited data, reinforcement accounts for 45 to 65 percent of total cost. This paper couples a complete MSE wall design routine with a highly efficient optimization model for optimum design of mechanically stabilized earth walls. The design algorithm benefits from limit equilibrium technique to calculate the external and internal stability of the wall considering common safety factors. The proposed safety factors are treated as constraint to the problem. The optimization model uses GA to search for optimum combination of the design variables to satisfy the required safety factors. Integration of simulation- optimization approaches for optimum design of MSE walls is the first in its kind which has been overlooked in the literature. Application of the model in few case examples shows that up to 15 percent may be saved in design specific cost in relatively high walls.