International Journal of Civil and Structural Engineering Research ISSN 2348-7607 (Online) Vol. 6, Issue 2, pp: (248-253), Month: October 2018 - March 2019, Available at: www.researchpublish.com
Geotechnical Design Optimisation of pile groups based on Particle Swarm Optimisation Technique Adamu Bakoji1, Abdussamad Ismail2, Abdulrahman Haruna3 1
Nigerian Building and Road Research Institute (NBBRI), Kano zonal office, Nigeria. 2
Department of Civil Engineering Bayero University Kano, Nigeria
3
Department of Building Technology Abubakar Tafawa Balewa University A.T.B.U Bauchi, Nigeria
Abstract: This research work presents a geotechnical design optimisation algorithm for pile groups based on particle swarm optimisation (PSO) technique. The main objective of the research is to develop a computer program for optimising the size and configuration of pile groups using PSO, while satisfying the Eurocode 7 geotechnical design criteria. PSO is a gradient-free bio-inspired search algorithm capable of achieving global optimum by virtue of its capacity to cover a wide area searching for the best solution. The PSO design optimisation of pile groups were began with the generation of particle population with each member representing a set of pile groups and must satisfy the EC7 design criteria. The objective function of the optimisation is to minimised construction cost. The design variables were: pile diameter (D), length (L), thickness of the pile cap (TH), pile spacing (S), number of piles (N). and the input into the work were soil sub-surface profile, and loads. Two types of piles (bored and driven) are considered in the design optimisation and the static axial loads of 500kN, 2000kN, 4000kN, 8000kN, and 16000kN are considered, and the design were carried out in accordance with Eurocode 7. Cohesive and cohesion-less materials with multilayer thickness are also considered. The results showed that both types of piles (bored and driven) satisfied load ratio condition in both cohesive and cohesion less soils. The results have also shown that particle swarm optimisation (PSO) based design code developed during this research has been able to obtain optimised parameters involved in the design of pile groups. Keywords: Piles, Optimisation, Algorithms, Program.
I. INTRODUCTION Piles foundations are a kind of deep foundations formed by long, slender, columnar elements typically made from steel or reinforced concrete and sometimes timber. A foundation is described as deep when its depth is more than three times its breadth [1]. Pile foundations are mainly to transfer axial and lateral loads from superstructure, through weak, compressible strata or water onto stronger, more compact, less compressible and stiffer soil or rock [2]. They are used for large structures, and in situations where the subsurface materials are not suitable to prevent excessive settlement. Generally, piles are classified based on their load carrying ability as; end-bearing piles (where most of the friction is developed at the toe of the pile, bearing on a hard layer) or friction piles (where most of the pile-bearing capacity is developed by shear stresses along the sides of the pile, suitable when harder layers are too deep). Most piles use some end-bearing and some friction, in order to resist the action of loads. A. Background to Eurocode7 Eurocode 7 part 1 (EN 1997-1) was released by the European committee for standardization (CEN) in November 2004 for publication as a national standard in 30 countries throughout the European Union and the European free trade association (EFTA). The British standards institution published this standard as Bs EN 1997-1 in December 2004.The design of pile foundations is the subject of section 7 of Eurocode 7 part 1, covering topics such as: limit states; actions and design
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