20 7 Proposal Deformation Of MSE Walls Comments 9 30 2013

NCHRP 20-7 Proposed Research Needs Statement Submitted by: Subcommittee on Bridges and Structures AASHTO Technical Committee T15 Substructures and Retaining Walls Mr. Jawdat Siddiqi, P.E., Chair September 30, 2013

TITLE Deformation of MSE Walls

BACKGROUND / NEEDS STATEMENT Although there has been some research on the vertical and horizontal deformations of MSE walls, currently there is little guidance describing how to predict MSE wall deformations either during or post construction. In addition, there is very little research that has been done to predict deformations of MSE wall supporting bridge loads. This work is not intended to evaluate foundation settlement below the MSE wall but to look at the MSE fill compression and associated lateral deflection due to its self-weight, dynamic construction effects (compaction) and additional surcharges above the wall. This information is important in order to better evaluate the serviceability of MSE walls.

From recent research it can be deduced that the MSE wall deformation is associated with many variables including fill gradation and strength, reinforcement type and spacing (horizontal or vertical), facing stiffness associated with facing type and connection strength, location of footing relative to wall face, and abutment wall height. These variables may also have an influence on the nominal strength limit state capacity of the abutment walls.

LITERATURE SEARCH SUMMARY

References:  Adams, M., Nicks, J., Stabile, T., Wu, J., Schlatter, W. and Hartmann J. (2011a). Geosynthetic Reinforced Soil Integrated Bridge System Interim Implementation Guide, Report No. FHWAHRT- 11-026, Federal Highway Administration, McLean, VA.  Adams, M., Nicks, J., Stabile, T., Wu, J., Schlatter, W. and Hartmann J. (2011b). Geosynthetic Reinforced Soil Integrated Bridge System Synthesis Report, Report No. FHWA-HRT-11-027, Federal Highway Administration, McLean, VA.  Al-Hussaini, M., and Perry, E. B., 1978, “Field Experiment of Reinforced Earth Wall,” Symposium on Earth Reinforcement, Pittsburgh, ASCE, pp. 127-156.  Bastick, M., Schlosser, F., Segrestin, P., Amar, S., and Canepa, Y., 1993, “Experimental Reinforced Earth Structure of Bouron Marlotte: Slender Wall and Abutment Test,” Proceedings International Symposium on Soil Reinforcement, Full Scale Experiments of the 80’s, Paris, pp. 201-228.  Bathurst, R., Blatz, J., and Burger, M., 2003, “Performance of Instrumented Large-Scale Unreinforced and Reinforced Embankments Loaded by a Strip Footing to Failure,” Canadian Geotechnical Journal, Vol. 40, pp. 1067-1083.  Bathurst, R. J., Miyata, Y., and Allen, T.M., 2010, “Invited Keynote Paper, Facing Displacements in Geosynthetic Reinforced Soil Walls,” Earth Retention Conference 3 (ER2010), ASCE Geo-Institute Bellevue, WA, pp. 442-459.  Berg, R.R., Christopher, B.R. and Samtani, N.C., Design and Construction of Mechanically Stabilized Earth Walls and Reinforced Soil Slopes, FHWA NHI-10-024 Vol I and NHI-10-025 Vol II, U.S. DOT, Federal Highway Administration, Washington, D.C., 2009, pp 306 (Vol I) and 378 (Vol II).  Christopher, B. R., Gill, S. A., Giroud, J.-P., Juran, I., Mitchell, J. K., Schlosser, F., and Dunnicliff, J., 1990, Reinforced Soil Structures, Vol. 1 & 2 Design and Construction Guidelines, and Summary of Research and Systems Information, FHWA Report FHWA-RD-89-043, 443 pp.  Damians, I.P., Bathurst, R.J., Josa, A., Lloret, A., Albuquerque, P.J.R. (2013), Vertical-Facing Loads in Steel-Reinforced Soil Walls, ASCE Journal of Geotechnical and Geoenvironmental Engineering, 2013.139, P1419-1432.  Wu, J.T.H., Lee, K.Z.Z., Helwany, S.B. and Ketchart, K. (2006). Design and Construction Guidelines for Geosynthetic-Reinforced Soil Bridge Abutments with a Flexible Facing, NCHRP Report 556, Transportation Research Board, Washington, D.C.

RESEARCH OBJECTIVE A study to investigate the impact of facing type, reinforcement strength, spacing and stiffness, construction methods, and fill types on vertical and horizontal deformation of MSE walls is needed to develop procedures to predict vertical and horizontal deformation of MSE walls supporting concentrated bridge loads on shallow foundations. There are currently several papers and reports published on the subject of load bearing MSE walls, as well as ongoing research, though much of it is based on strength limit state design. The proposed research differs in that it will explore the deformation, or service limit state, performance. The objective of this proposed research is to develop a synthesis of existing and ongoing work to assess what is currently known about MSE wall deformation when subjected to bridge abutment spread footing loads, potentially provide provisional guidance on the deformation predictions for MSE walls, and to highlight the research gaps to focus future work on the subject.

An outcome of the work would be to summarize the available data that could be used to develop deformation prediction methods for MSE walls, and a potential improvement to guidance in AASHTO Section 11.10 and in FHWA MSE Wall Design and Construction Manual.

WORK TASKS Tasks anticipated in this project include the following:  Synthesize past research on MSE wall deformations  Compile all available in-service and field test data for MSE wall deformations under various loading conditions (e.g. traffic, bridge, seismic, etc.)  Summarize ongoing research and corresponding scopes  Based on past and ongoing research, propose future research to fill in research gaps  If sufficient information exists, develop recommendations for interim guidance for serviceability evaluation of MSE walls.

URGENCY Use of shallow foundations in lieu of deep foundations (piles and drilled shafts) to support bridges on MSE wall abutments provides significant savings in construction cost, construction time, and performance benefits to transportation agencies. Current guidance on the prediction of vertical and horizontal deformation of MSE walls under footing loads is not specific, consisting of only limited guidance based on experience. FUNDING REQUESTED AND TIME REQUIRED It is estimated that this research will take 9 months to complete and will require $100,000.

CONTACT PERSONS Tony Allen State Geotechnical Engineer WSDOT State Materials Laboratory P.O. Box 47365 Olympia, WA 98504-7365 Phone: (360) 709-5450 [email protected]

Daniel Alzamora Geotechnical Engineer Federal Highway Administration Office of Technical Services - Resource Center 12300 W. Dakota Ave. Suite 340 Lakewood, CO 80228 Phone: (720) 963-3214 [email protected]