Geotextiles and Geomembranes 26 (2008) 335–349 Seismic response of reinforced soil retaining wall models: Influence of backfill relative density G. Madhavi Latha à , A. Murali Krishna Department of Civil Engineering, Indian Institute of Science, Bangalore 560012, India Received 24 May 2007; received in revised form 10 November 2007; accepted 29 November 2007 Available online 5 February 2008 Abstract This paper presents the results of shaking table tests on model reinforced soil retaining walls in the laboratory. The influence of backfill relative density on the seismic response was studied through a series of laboratory model tests on retaining walls. Construction of model retaining walls in the laminar box mounted on shaking table, instrumentation and results from the shaking table tests are described in detail. Three types of walls: wrap- and rigid-faced reinforced soil walls and unreinforced rigid-faced walls constructed to different densities were tested for a relatively small excitation. Wrap-faced walls are further tested for higher base excitation at different frequencies and relative densities. It is observed from these tests that the effect of backfill density on the seismic performance of reinforced retaining walls is pronounced only at very low relative density and at the higher base excitation. The walls constructed with higher backfill relative density showed lesser face deformations and more acceleration amplifications compared to the walls constructed with lower densities when tested at higher base excitation. The response of wrap- and rigid-faced retaining walls is not much affected by the backfill relative density when tested at smaller base excitation. The effects of facing rigidity were evaluated to a limited extent. Displacements in wrap-faced walls are many times higher compared to rigid-faced walls. The results obtained from this study are helpful in understanding the relative performance of reinforced soil retaining walls constructed to when subjected to smaller and higher base excitation for the range of relative density employed in the testing program. r 2007 Elsevier Ltd. All rights reserved. Keywords: Shaking table tests; Seismic response; Laminar box; Reinforced soils; Wrap-faced retaining walls; Geotextiles 1. Introduction Reinforced soil retaining walls offer competitive solu- tions to earth retaining problems associated with less space and more loads posed by tremendous growth in infra- structure in recent times. Studies on these important structures are reported under static and working conditions in the literature since their evolution (Edgar et al., 1989; Wong et al., 1994; Ho and Rowe, 1996; Bathurst et al., 2005; Kazimierowicz-Frankowska, 2005; Skinner and Rowe, 2005). Their dynamic behavior has been the subject of several researchers for past 25 years (Richardson and Lee, 1975; Cai and Bathurst, 1995; Ling et al., 1997; Bathurst and Hatami, 1998; Matsuo et al., 1998; Perez and Holtz, 2004; Nova-Roessig and Sitar, 2006; Nouri et al., 2006; Won and Kim, 2007). Efficient functioning of reinforced soil retaining walls during the recent cata- strophic earthquakes is observed and reported in literature (Tatsuoka et al., 1995; Sandri, 1997; Kramer and Paulsen, 2001; Tatsuoka et al., 2007). Studying the performance of physical models of reinforced retaining walls under cyclic ground shaking condition can help to understand better how these walls actually behave during earthquakes. Reinforced retaining walls can be constructed using different reinforcing materials and facing systems. Reinforcing materials may be of relatively inextensible steel strips, sheet or relatively extensible polymer products like geotextiles, geogrids and geomembranes. Wall facing types may include: wrap facing, full height rigid (FHR) facing, segmental block facing and modular block facing (Holtz, 2001). ARTICLE IN PRESS www.elsevier.com/locate/geotexmem 0266-1144/$ - see front matter r 2007 Elsevier Ltd. All rights reserved. doi:10.1016/j.geotexmem.2007.11.001 à Corresponding author. Tel.: +91 80 2293 3123; fax: +91 80 2360 0404. E-mail addresses: madhavi@civil.iisc.ernet.in (G. Madhavi Latha), amurali@civil.iisc.ernet.in (A. Murali Krishna).