Three-dimensional optimization of wave barriers for mitigating ground vibrations induced by underground train.

Underground train–induced vibrations can cause nearby residents discomfort, damage to buildings, and disturbance for equipment. One of the most effective ways to reduce vibrations is using wave barriers along the propagation path of the waves. Many parameters are involved in determining the efficiency of these barriers: the barrier's dimension, distance from the source of vibration, and material property, to name a few. Simultaneous study of these parameters is complex since numerical analysis of alternatives is time-consuming. Therefore, in this study, by coupling the three-dimensional finite element method and an optimization algorithm, an attempt is made to provide a comprehensive solution to find the optimal wave barriers for Tehran metro line 4 as a case study. The current study evaluates two strategies: using in-filled trenches and topology-optimized barriers. In the first strategy, results show that soft-material trenches with maximum depth close to the observation point have the best performance. Further investigations on jet grout trenches show better performance in stiffer soil and lower train speed. Using dual trenches improves performance only up to 2%, so it does not provide a suitable option. For various practical reasons, there may be no tendency to use soft-material trenches, which perform well in vibration reduction. Therefore, in the second strategy, the improvement of a hard trench (jet grout) performance by topology optimization is investigated. According to this study, topology optimization is an effective method for improving barrier performance. [ABSTRACT FROM AUTHOR]