نوع مقاله : یادداشت فنی
نویسنده
گروه مهندسی عمران، دانشگاه فنی و حرفهای، تهران، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسنده [English]
The effectiveness of the application of the metaheuristic algorithms in the optimal design of retaining structures is investigated in this paper. For this purpose, an on-going Tabriz metro station project with a deep excavation pit is selected here as a case study. The retaining system of the project consists of secant pile walls supported by a layer of struts. The piles have circular section consisting of reinforced concrete cores covered by steel sleeves and the struts are made of steel rectangular hollow sections. A detailed finite element model is developed in OpenSees platform including all the constructional process in order to perform static analyses. Four different metaheuristic algorithms, namely Genetic, Particle swarm optimization, Bee, and Biogeography-based algorithms are chosen for the optimization problem. The pile external diameter, the steel tube stiffness, the number of longitudinal bars inside the concrete core and their diameters, the center-to-center spaces of the pile elements, the dimensions of structs and their center-to-center spaces, the location of the structs in depth and the buried depth of pile elements are selected as optimization variables. The total cost of the retaining system is considered as an objective function which should be minimized in the design space of the variables. For the optimization purpose, an integration of OpenSees software with MATLAB platform is done to join the modeling space with the mentioned optimization algorithms. The number of iterations for each run is assumed to be 400, which is also considered as a termination criterion. The optimization process is performed 50 times and the best response is reported here. The results demonstrate an excellent performance of Genetic algorithm in obtaining the optimum solution respect to other three considered algorithms. It exhibits a proper standard deviation and convergence rate in producing the optimum response. It is shown that the soil stress is increased in the depth where struts are installed, while they are reduced near the ground level, where the deflection of piles creates the active situation for soil. This is true considering the results of all algorithms. Proceeding the excavation phase increases the soil stress as well as the pile deformation. It can be also obtained that providing a layer of strut seems necessary for reducing pile movements as well as their buried depth.
کلیدواژهها [English]
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