Estimation of Maximum Lateral Displacement of the Back to Back Mechanically Stabilized Earth Walls

Document Type : Research Paper

Authors

1 MSc Student, Department of Civil Engineering, Faculty of Engineering, Shahed University, Tehran, Iran

2 Assistant professor, Department of Civil Engineering, Faculty of Engineering, Shahed University, Tehran, Iran

Abstract

Back to back mechanically stabilized earth walls (MSEWs) are the structures usually used in two sides of bridge abutments and ramps. Although this type of MSEW is commonly constructed, but limited number of design guidelines are available in this regard. According to the FHWA recommendations, if the ends of reinforcements at two sides are close enough to each other, the walls are considered as back to back for the design practice; otherwise, each wall is designed independently. In this study, considering a fixed width and height for the walls, variations of the length and vertical spacing of the geogrids, as well as friction angle of the soil, were evaluated through 196 different models built and analyzed using FLAC 2D. The critical slip surface was compared in normal and back to back conditions using limit equilibrium method. Results of modeling include lateral earth pressure behind the wall, maximum force mobilized in geogrids and lateral displacements of the wall for different cases of the study. Accordingly, it was found that maximum lateral displacement of the wall usually occurs in 0.35 to 0.57 of the wall height. Based on the maximum horizontal displacements, the recommended boundary for the two different mechanisms of MSEWs was approved. Using the maximum lateral displacements, the change in wall behavior was studied and a non-linear model with the form of power-law was developed to estimate maximum lateral displacement of the wall with respect to the governing parameters. Coefficients of determination of the analysis results for normal MSEW, back to back MSEW and both cases were calculated as 0.953, 0.969 and 0.947, respectively. This confirms the suitable accuracy of the proposed formulae to estimate maximum lateral displacements as well as the appropriate exhibition of the governing physical trends.

Keywords


Adams, M., Nicks, J., Stabile, T., Wu, J., Schlatter, W. and Hartmann, J. 2011. “Geosynthetic Reinforced Soil Integrated Bridge System”. Interim Implementation Guide, No. FHWA-HRT-11-026.
Benmebarek, S., Attallaoui, S. and Benmebarek, N. 2016. “Interaction analysis of back-to-back mechanically stabilized earth walls”. J. Rock Mech. Geotech. Eng., 8: 697-702.
Benmebarek, S. and Djabri, M. 2017. “FEM to investigate the effect of overlapping reinforcement on the performance of back-to-back embankment bridge approaches under self-weight”. Transport. Geotech., 11: 17-26.
Berg, R. R., Christopher, B. R. and Barry, R. 2009. “Design of Mechanically Stabilized Earth Walls and Reinforced Soil Slopes”. Publication No. FHWA-NHI-10-043, Federal Highway Administration.
Djabri, M. and Benmebarek, S. 2016. “FEM analysis of back-to-back geosynthetic-reinforced soil retaining walls”. Int. J. Geosynth. Ground Eng., 2(3): 26.
El-Sherbiny, R., Ibrahim, E. and Salem, A. 2013. “Stability of back-to-back mechanically stabilized earth walls”. Geo-Congress 2013, San Diego, California, USA, pp. 555-565.
Han, J. and Leshchinsky, D. 2010. “Analysis of back-to-back mechanically stabilized earth walls”. Geotext. Geomembranes, 28: 262-267.
Hardianto, F. and Truong, K. 2010. “Seismic deformation of back-to-back mechanically stabilized earth (MSE) walls”. Earth Retention Conference 3, Bellevue, Washington, USA, pp. 704-711.
Itasca. 2011. “User’s Guide Fast Lagrangian Analysis of Continua- FLAC, Ver. 7.0”. Itasca Ltd.
Katkar, H. and Viswanadham, B. 2011. “Some studies on the behaviour of back-to-back geosynthetic reinforced soil walls”. Proceedings of Indian Geotechnical Conference, Kochi, pp. 911-914.
Rocscience. 2010. “User’s Guide SLIDE, ver. 6.0”. Rocscience Ltd.
Shinoda, M. and Bathurst, R. J. 2004. “Lateral and axial deformation of PP, HDPE and PET geogrids under tensile load”. Geotext. Geomembranes, 22(4): 205-222.
Tajiri, N., Sasaki, H., Nishimura, J., Ochiai, Y. and Dobashi, K. 1996. “Full-scale failure experiments of geotextile-reinforced soil walls with different facings”. IS-Kyushu 9, Third International Symposium on Earth Reinforcement, Balkema, Rotterdam, The Netherlands.