TECHNICAL NOTE Horizontal Pullout Capacity of a Group of Two Vertical Strip Anchors Plates Embedded in Sand Paramita Bhattacharya • Jyant Kumar Received: 7 May 2011 / Accepted: 2 December 2011 / Published online: 13 December 2011 Ó Springer Science+Business Media B.V. 2011 Abstract The horizontal pullout capacity of a group of two vertical strip anchor plates placed along the same vertical plane in sand, has been determined by using the lower bound finite element limit analysis. The effect of vertical spacing (S) between the anchor plates on the magnitude of the total group horizontal failure load (P uT ) has been determined for different combinations of H/B, d// and /. The magnitude of P uT has been obtained in terms of a group efficiency factor, g c , with respect to the failure load for a single vertical plate with the same H/B. The magnitude of g c becomes maximum corresponding to a certain critical S/B, which has been found to lie between 0.5 and 0.8. The value of g c for a given S/B has been found to become larger for greater values of H/B, /, and d. Keywords Anchors  Failure  Finite elements  Limit analysis  Pullout capacity  Sand 1 Introduction Vertical anchors are often used to support retaining walls, sheet piles and bulkheads. A number of investigations have been reported in literature to determine the horizontal pullout resistance of a single vertical plate anchor. These studies are based on (1) conventional 1-g laboratory model tests (Das and Seeley 1975), (2) centrifuge model tests (Dicken and Leung 1985), (3) the limit equilibrium method (Mey- erhof 1973), (4) the method of the stress characteristics (Neely et al. 1973; Kumar and Rao 2004), (5) the elastoplastic finite element method (Rowe and Davis 1982), (6) the upper bound limit analysis (Murray and Geddes 1989; Merifield et al. 2001; Kumar 2002; Merifield and Sloan 2006), and (7) the lower bound limit analysis (Merifield et al. 2001; Merifield and Sloan 2006). It needs to be mentioned that anchors are usually placed in a group. Hardly any investigation seems to be reported in literature where an attempt has been made to determine the horizontal pullout capac- ity of a group of vertical anchors placed along the same vertical plane. In the present article, a lower bound solution has been determined for computing the total horizontal pullout capacity of a group of two vertical strip anchors embedded in sand and spaced at a given clear distance (S) along the same vertical plane. The effect of spacing has been examined on the magnitude of the group failure load for different combinations of H/B, d// and /. Failure patterns have also been generated from the analysis for a few cases. P. Bhattacharya  J. Kumar (&) Department of Civil Engineering, Indian Institute of Science, Bangalore 560012, India e-mail: jkumar@civil.iisc.ernet.in P. Bhattacharya e-mail: paramita@civil.iisc.ernet.in 123 Geotech Geol Eng (2012) 30:513–521 DOI 10.1007/s10706-011-9484-z