Seismic Bearing Capacity of Shallow Strip Footings on Sand Deposits with Weak Inter-layer
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ORIGINAL PAPER
Seismic Bearing Capacity of Shallow Strip Footings on Sand Deposits with Weak Inter-layer Hamed Haghsheno . Reza Jamshidi Chenari Tooraj Banirostam
. Sina Javankhoshdel .
Received: 27 July 2019 / Accepted: 11 July 2020 Ó Springer Nature Switzerland AG 2020
Abstract The main objective of this study is to evaluate the ultimate seismic bearing capacity of a shallow strip footing resting on a frictional soil stratum containing a weak intervening layer. The majority of the studies throughout the literature pertain to the static loading condition. The previous seismic analyses have also been devoted to the studies on the bearing capacity of shallow strip footings resting on a two-layered soil. The influence of weak middle layer on the pseudo-static seismic bearing capacity of shallow foundations is the main focus of the present study. To determine the seismic bearing capacity, the limit equilibrium method (LEM) was combined with the pseudo-static seismic loading approach. Bearing capacity was defined by a single equivalent coefficient which combines the contributions of cohesion, surcharge and soil weight. A two-wedge failure surface, known as the Coulomb failure mechanism, was adopted to model the slip lines in each layer to H. Haghsheno R. Jamshidi Chenari (&) Department of Civil Engineering, Faculty of Engineering, University of Guilan, Rasht, Iran e-mail: [email protected]; [email protected] S. Javankhoshdel Rocscience Inc., 54 Saint Patrick St, Toronto, ON, Canada T. Banirostam Central Tehran Branch, Islamic Azad University, Tehran, Iran
calculate the seismic bearing capacity of the overlying shallow strip footing. The Particle Swarm Optimization (PSO) algorithm was invoked to seek the optimal bearing capacity value under different strength and loading conditions. In order to verify the validity of the presented formulations, the results were compared with some Finite Elements Method (FEM) analyses available in literature. Furthermore, the influence of the embedment depth, thickness, and strength of the weak inter-layer on the seismic bearing capacity of the shallow footing is investigated in the presence of different seismic loading arrangements. The results of this study could be very helpful in the seismic analysis and design of shallow foundations overlying a soil medium containing a weak layer of various strengths. Keywords Bearing capacity Limit equilibrium method (LEM) Pseudo-static Weak inter-layer Particle swarm optimization (PSO)
1 Introduction Natural soils are often formed in discrete layers, and shallow foundations are sometimes located on soils with layered structures. Many researchers have investigated the problem of the bearing capacity of foundations resting on layered soils. The first approach employed to solve the bearing capacity of a foundation lain over a two-layer clay deposit under static loading
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Geotech Geol Eng
was presented by Button (1953). He assumed a general shear failure mechanism alon
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