Project:  Seismic Stability of Mechanically Stabilized Earth Structures

PI(s):   Steve Kramer, Bob Holtz

Sponsor:   NSF

Objective:   To develop improved procedures for predicting permanent deformations of mechanically stabilized earth slopes.

Research Approach:   The use of mechanical reinforcement has been shown to allow economical construction of steep slopes in many types of soil. Design procedures for static loading conditions have been developed and shown to lead to satisfactory performance when good construction practices are followed. The economy of this method of slope construction has led to its increasing use. In seismically active regions, however, mechanically stabilized slopes may be subject to strong inertial forces from earthquake ground shaking. Methods of accounting for the effects of dynamic loading on the performance of reinforced structures are not well developed; available procedures are generally based on a pseudo-static representation of earthquake effects, which provides no information on permanent deformations. Because performance is related to permanent deformations, these procedures are unable to provide accurate estimates of performance.

This research involves the performance and interpretation of physical model tests on reinforced slopes. A series of centrifuge and shaking table models were tested using different geosynthetic reinforcements and different reinforcement geometries (lengths, spacings, etc.). The results of these tests are being interpreted in terms of permanent deformations; a simplified model for prediction of the permanent deformations is being developed and calibrated against the model test data. Recommendations for seismic design of reinforced slopes will be developed.

For more information send E-Mail to: kramer@u.washington.edu