This project is the second phase of a study to examine the design requirements for repairing roadways on steep hillsides by the deep patch method. A finite difference model was used in a parametric study to generate design guidelines for deep patch slope repairs. The design recommendations developed in Phase I were based on analytical evaluations and require experimental validation.

The scope of this project is to validate the deep patch repair design technique developed in Phase I by performing several scaled model laboratory tests using a centrifuge. To accomplish this goal, first an extensive literature review to obtain knowledge of the use of centrifuge testing to study slope behavior, geosynthetics and other soil improvements will be performed. From this, an experimental design will be developed to examine the performance of different deep patch repair configurations (i.e., reinforcement vertical spacing, depth of deep patch, and geosynthetic strength and configuration – biaxial versus uniaxial grids) and to validate the design model developed in Phase I. A series of unreinforced and reinforced slope configurations will then be tested using a large centrifuge to study their behavior and document their performance. Finally, a final report will be written to synthesize the information collected during this research effort and to document the outcomes of the testing and data analysis.