Civil and Environmental Engineering
University of Massachusetts
Amherst, Ma. 01003

 

NATIONAL GEOTECHNICAL EXPERIMENTATION SITE

University of Massachusetts – Amherst

         The NGES at the University of Massachusetts is an active geotechnical research site with a number of individual studies currently underway to investigate the performance of deep and shallow foundations in clay and the performance of other geotechnical structures.  Previous projects have included special in situ testing studies and the study of the failure of a full scale soil nail wall. The site is composed of a thick deposit of lake clay that has a very well developed overconsolidated crust at the surface grading into a very soft clay with depth.

        1. Axial Behavior of Drilled Shafts in Clay

    The axial behavior of drilled shafts in clay and the influence of construction defects on field performance are being evaluated. A number of 3 ft. diameter drilled shafts with a length of 55 ft. have been installed and load tested in axial compression. In addition to static load testing, impact and StatNamic tests have also been performed. The shafts have also been evaluated using a number of different techniques to determine the location and extent of defects.

         2.  Lateral Loading of Drilled Shafts in Clay

     The lateral load behavior of drilled shafts is also being evaluated by testing a number of prototype and full scale drilled shafts. Pairs of shafts are loaded at the same time in order to evaluate the variability of the behavior. The figure below shows typical a load-displacement curve. 

 

 

 

          3. Behavior of Geosynthetic Reinforced Soil Bridge Piers

    Four full-scale Geosynthetic Reinforced Soil (GRS) bridge piers were recently constructed and load tested. The figure below shows the construction in progress. The piers investigated the influence of fabric spacing and fill compaction on the axial load-displacement performance. Each of the piers was placed on a different shallow foundation so that the effectiveness of ground improvement could be evaluated. The long-term settlement of the foundations is currently being measured.

 

         4. Settlement of Shallow Foundations

    Two full scale footings have been installed and are being incrementally loaded to investigate the long-term load-settlement performance in stiff clay crust. A 5 ft. x 5 ft. and 10 ft. x 10 ft. concrete footing are being loaded with a dead weight load each year over the next several years.

 

          5.  Pullout Capacity of Helical Piles

     A series of helical piles have been installed and are being load tested in axial tension in order to evaluate current design procedures. Both shallow and deep installations are being investigated. Additional testing will examine group effects and long-term creep under constant load. The figure bellows shows the load-displacement curve of a 12 in. diameter plate installed at a depth of 10 ft.

 

 

         6.  Behavior of Geopiers

      Full size Geopier foundations have been installed ant the site and will be load tested in compression and tension in order to evaluate their performance as an intermediate foundation system in clay.

     

 

           7. Soil Nail Wall

     A full scale Soil Nail Wall was constructed and then intentionally failed by undercutting to evaluate current design procedures.

    

For more information on the NGES at the University of Massachusetts, contact Dr. Alan Lutenegger, Site Manager, by email at lutenegg@ecs.umass.edu. Also visit the NGES web site at www.unh.edu/nges/

 

Bibliography of Technical Publications Related to the NGES UMass - Amherst

Benoit, J. and Lutenegger, A.J., 1992. Measurement of Lateral Stresses in Soft Clay. Proceedings of the Wroth Memorial Symposium on Predictive Soil Mechanics. pp. 56-74.

DeGroot, D.J., 1999. Laboratory Measurement of Undrained Shear Behaviour of Clays. Proceedings of the International Conference on Offshore and Nearshore Geotechnical Engineering, pp.

DeGroot, D.J. and Lutenegger, A.J., 1993. A Comparison Between Field and Laboratory Measurements of Hydraulic Conductivity in a Varved Clay. Hydraulic Conductivity and Waste Containment Transport in Soils, ASTM STP 1141, pp. 300-317.

DeGroot, D.J. and Lutenegger, A.J., 2002.

Finno, R., Chao, H.-C., Gassman, S., and Zhou, P., 2002. Non-Destructive Evaluation of Drilled Shafts at the Amherst NGES Test Section. Deep Foundations 2002, Vol. 2, pp. 883-897.

Iskander, M. Kelley, S., Ealy, C., and Roy, D., 2001a. Load Tests on Drilled Shafts with Planned Defects in Varved Clay. Transportation Research Board

 Iskander, M. Kelley, S., Ealy, C., and Roy, D., 2001b. Class A Prediction of Construction Defects in Drilled Shafts. Transportation Research Board

Kates Martin, G. and Mayne, P.W., 1997. Seismic Flat Dilatometer Tests in Connecticut Valley Varved Clay. Geotechnical Testing Journal, ASTM, Vol. 20, No. 3, pp. 357-361.

 Lutenegger, A.J., 1995. Geotechnical Behavior of Overconsolidated Clay Crusts. Transportation Research Record, No. 1479, pp. 61- 74.

 Lutenegger, A.J., 2000. National Geotechnical Experimenation Site: University of Massachusetts. National Geotechnical Experimentation Sites, ASCE, pp. 102-129.

 Lutenegger, A.J. and DeGroot, D.J., 1992. Measurement of Hydraulic Conductivity in Clay Using Push-In Piezometers. Current Practices in Ground Water and Vadose Zone Investigations, ASTM STP 1118, pp. 362-374.

 Lutenegger, A.J. and Miller, G.A., 1993. Evaluation of Dilatometer Method to Determine Axial Capacity of Driven Model Pipe Piles in Clay. Use of In Situ Tests for Design of Deep Foundations, ASCE, pp. 40-63.

 Lutenegger, A.J. and Miller, G.A., 1993. Behavior of Laterally Loaded Drilled Shafts in Stiff Soil. Proceedings of the 3rd International Conference on Case Histories in Geotechnical Engineering, Vol. 1, pp. 147-153.

 Lutenegger, A.J. and Miller, G.A., 1994. Uplift Capacity of Small-Diameter Drilled Shafts from In Situ Tests. Journal of Geotechnical Engineering, ASCE. Vol. 120, No. 8, pp. 1362-1380.

 Lutenegger, A.J. and Miller, G.A., 1998. Tension Tests on Drilled Micropiles in a Stiff Clay. Proceedings of the 4th International Conference on Case Histories in Geotechnical Engineering, Vol. pp.

 Lutenegger, A.J. and Mitchell, M., 2000. Pullout Tests on Inclined Grouted Anchors in the Clay Crust at the University of Massachusetts National Geotechnical Experimentation Site. National Geotechnical Experimentation Sites, ASCE,  pp. 321-335.

 Lutenegger, A.J. and Dearth, A., 2001. Scale Effects of Laterally Loaded Drilled Shafts in Clay. Foundations and Ground Improvement, ASCE, pp. 554-564.

 Miller, G.A. and Lutenegger, A.J., 1993. Analysis of Small Pipe Piles Using the Field Vane. Proceedings of the 3rd International Conference of Case Histories in Geotechnical Engineering, Vol. 1, pp. 154-160.

 Miller, G.A. and Lutenegger, A.J., 1994. Effects of Plugging on Piles Installed in an Overconsolidated Clay. Proceedings of the International Conference on Deep Foundations, Vol. 2, pp. 525-540.

 Miller, G.A. and Lutenegger, A.J., 1997. Influence of Pile Plugging on Skin Friction in Overconsolidated Clay. Journal of Geotechnical and Geoenvironmental Engineering, ASCE, Vol. 123, No. 6, pp. 525-533.

 Oral, T. and Sheahan, T.C., 1998. The Use of Soil Nails in Soft Clays. Design and Construction of Earth Retaining Systems, ASCE, pp. 26-40.

 Sheahan, T.C., 2000. A Field Study of Soil Nails in Clay at the University of Massachusetts - Amherst National Geotechnical Experimentation Site. National Geotechnical Experimentation Sites, ASCE, pp. 250-263.

 Sheahan, T.C. and Ho, C.L., 2003. A Simplified Trial Wedge Method for Soil Nailed Wall Analysis. Journal of Geotechnical and Geoenvironmental Engineering, ASCE, (in press)

 
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