Contents lists available at ScienceDirect Computers and Geotechnics journal homepage: www.elsevier.com/locate/compgeo Research Paper Undrained seismic bearing capacity of strip footing placed on homogeneous and heterogeneous soil slopes by finite element limit analysis Amin Keshavarz a, ⁎ , Majid Beygi b , Ramin Vali c a Department of Civil Engineering, Persian Gulf University, Bushehr, Iran b Department of Civil Engineering, Yazd University, Yazd, Iran c Department of Civil Engineering, Faculty of Shahid Mohajer, Isfahan Branch, Technical and Vocational University (TVU), Isfahan, Iran ARTICLE INFO Keywords: Finite element limit analysis Undrained bearing capacity Heterogeneous soil slope Seismic bearing capacity Strip footing ABSTRACT In this paper, undrained seismic bearing capacity of a strip footing placed on a slope in both homogeneous and heterogeneous soils is investigated using the lower and upper bounds of finite element limit analysis. Effective parameters on the bearing capacity and failure patterns are examined. Design charts and tables are provided to evaluate undrained seismic bearing capacity of slopes as a function of dimensionless parameters. The results of the present study are compared with other solutions. 1. Introduction Calculating the bearing capacity of a strip footing on the level ground is one of the most classical subjects in geotechnical engineering. There are, however, many parameters which significantly affect the ultimate bearing capacity of a strip footing, and without doubt, the ground slope plays a significant role in this case. Many researchers have assessed the static bearing capacity of the footing located near the slope. Various methods have been adopted including the finite element method (FEM) [1,2], discontinuity layout optimization [3,4], limit equilibrium [5], upper bound [6,7], and the experimental analysis [8]. Among these, Leshchinsky [3] assessed the bearing capacity of a footing near the cohesive-frictional slopes. The results showed that the impact of all slope angles decrease by increasing the slope height to footing width ratio (B/H). Georgiadis [6] used an upper-bound approach to evaluate the undrained bearing capacity of a strip footing located on top of the slope. Also, Georgiadis [1] investigated the undrained bearing capacity of a strip footing located on the slope by considering the load inclination. Undrained stability of footings located on the purely cohesive slopes was evaluated by Shiau et al. [9] by the means of finite element upper and lower bound methods. The generalized Hoek- Brown criterion was used to evaluate the seismic bearing capacity of shallow foundations located near the rock slopes by Saada et al. [10]. Keskin and Laman [8] experimentally assessed the bearing capacity of a strip footing located in the sandy slope. It was found out that by in- creasing the distance from edge of the slope to the footing width ratio (L/B) up to five, the bearing capacity increases; however, for L/B ≥ 5, the ultimate bearing capacity reaches to a constant value, which is si- milar to the cases that the footing placed on a level ground. Leshchinsky and Xie [11] evaluated the bearing capacity of a spread footing near the cohesive-frictional slopes by using the discontinuity layout optimiza- tion method. Zhou et al. [4] evaluated the failure mechanism and the bearing capacity of a strip footing located on top of the slope affected by vertical loads. On the other hand, there are a few researches to evaluate the seismic bearing capacity of footings near the slopes. Seismic bearing capacity of a footing located on the slopes was assessed by Kumar and Mohan Rao [12] using the method of stress characteristics. The results showed that all bearing capacity factors decrease considerably by in- creasing the magnitude of earthquake acceleration coefficient. Askari and Farzaneh [13] used an upper-bound solution to find out the seismic bearing capacity of shallow foundations located near the slopes. Castelli and Motta [5] studied the static and seismic bearing capacity of a strip footing located near the slope using the limit equilibrium method. Based on their studies, using the superposition principle may leads to an unconservative design when the seismic reduction is great due to high seismic coefficients. Cinicioglu and Erkli [2] used finite element method to conduct a parametric study for evaluating the seismic un- drained bearing capacity of the surficial foundation near the slope. Design charts were presented based on the analyses. Note that in their study, the soil was homogeneous and undrained shear strength did not increase with depth. In this paper, the finite element limit analysis (FELA) is used to obtain the seismic undrained bearing capacity of a strip footing placed on https://doi.org/10.1016/j.compgeo.2019.103094 Received 28 March 2019; Received in revised form 25 April 2019; Accepted 9 May 2019 ⁎ Corresponding author. E-mail address: keshavarz@pgu.ac.ir (A. Keshavarz). Computers and Geotechnics 113 (2019) 103094 0266-352X/ © 2019 Elsevier Ltd. All rights reserved. T