A Modified Harmony Search Algorithm for the Optimum Design of Earth Walls Reinforced with Non-uniform Geosynthetic Layers

Abstract

Traditional design and construction of reinforced earth walls assumes uniform length and spacing of reinforcements. Even though the assumption simplifies the design and construction efforts, the inherently conservative approaches followed in picking the final values for the reinforcement length and spacing result in unnecessarily big construction costs. This paper presents an improved harmony search-based approach that can be adopted to optimize the design of Geosynthetic-reinforced earth walls. An existing improved harmony search algorithm is modified into a new harmony search algorithm by extending its capabilities to consider permutation-based operations for inter-dependent variables. The involved optimization procedures are discussed in a step-wise approach. This novel approach allows the consideration of non-uniform length and spacing for the reinforcement layers. As such, length of the Geosynthetic reinforcement and the spacing between adjacent Geosynthetic layers are taken as the design variables to be manipulated until the cost of construction is optimized. Static and dynamic loads are considered. the application of the proposed optimization technique is demonstrated on Geosynthetic-reinforced earth walls of height 5, 7 and 9 m. The extent of cost saving is assessed by comparing the results of this work and previous work. The previous work selected for comparison uses harmony search algorithm to optimize the design and construction of Earth Walls reinforced with uniform length- and spacing-Geosynthetic layers. The IHS-based optimization resulted in Cost reduction of up to 11 %.